Articles and Advice on Astronomy

Starting Out – Things to consider

Astronomy can be a very exciting and fulfilling hobby.  It can also be very expensive.  Many of the people that want to get into astronomy don’t know where to start, and consequently make mistakes that cause them to be frustrated and, in many cases, to eventually lose interest.  It makes a lot of sense to step back before you make the plunge and learn a bit so that you can avoid wasting time and money.  Here are a couple of things to think about as you consider the purchase of your first telescope.

1)      Ask yourself what it is you want to see and what you expect to see.

We see pictures of the heavens in magazines or on the internet.  They are truly amazing and may inspire us.  But it is important to remember that most of those pictures were taken by equipment that is far out of the amateur hobbyist’s reach.  Many of the pictures that you see were taken by the Hubble space telescope.  The Hubble space telescope cost Billions of dollars and was launched into space (costing millions more) to avoid the problems caused looking through the earth’s atmosphere.  This is not what you will see in your first telescope.  You will see objects with much less magnification and much less detail than you see in those pictures.  However, there is something magical about seeing the rings of Saturn, or the cloud bands on Jupiter, or the Orion Nebula with your own eyes.

2)      Consider how much money you can afford to spend.

Telescopes and their mounts can run from less than $200 to $10,000’s of dollars.  To some extent, you get what you pay for.  A well chosen rig that costs $10,000 will currently let you see more and will have more capability that a rig that costs $200.  However, is a $10,000 rig 50 times better than a $200 rig?  It is really a matter of opinion.  But, if you are interested in seeing the rings of Saturn, the moons of Jupiter and the craters and seas of the moon, a $200 rig can be ok.

3)      Consider how much time you have available to spend.

Learning astronomy and practicing it takes time.  If all you want to do is look at the planets and the moon, it is straightforward.  But for a lot of people, seeing the amazing sights of the solar system often leads to a desire to see much more.  Stars, nebulae, galaxies, star clusters, comets, etc., etc.  Just finding stars can be a major challenge and requires a lot of time and learning.  There are some miraculous devices that can decrease the learning time and improve your ability to find heavenly objects.  Computerized telescopes are now made with “go to” functionality.  This allows you to have the computer move your mount in such a way that it can find various objects for you at the touch of a button.  It takes a bit of learning to master a computerized “go to” telescope and mount, but it certainly decreases the necessary time investment.  Having one of these devices also increases the time you can actually spend observing objects and decrease the time that you spend finding the objects.  However, computerized “go to” mounts are much more expensive.  You can get into a good “go to” rig for between $1000 and $2000 although the high-end ones are going to cost you $2000 to $10000 or more.

4)       Remember, most astronomy is done at night!

While it is possible to get equipment that can be operated from the inside, it is very expensive and most beginning (and low cost) astronomy is done outside – in the dark – in the cold.  If that concerns you, astronomy might not be the right hobby.

5)      Decide whether you want to get into astrophotography.

Astrophotography adds cost and complexity to your astronomy, but it is a lot of fun!  You can take pictures of things that you cannot see with your eyes, even through the telescope.  You can do basic astrophotography with just about any decent camera (including the camera on your cellphone) but the more you want to do, the more expensive and difficult it becomes.  And if you want to do photography of deep space objects, you will need a mount that automatically tracks your target which is also much more expensive.  However, this is not a decision that you need to make immediately.  You can get into astrophotography later when you have learned a lot more.

All these items are good to think about, but by themselves they can’t make the decision for you.  In a future article, I will cover my suggestions on how to make your decision and how to be as cost-effective as possible when you do.

Choosing Your First Telescope

Telescopes come in a bewildering variety of shapes and sizes.  In addition, the mount that the telescope sits on is at least as important as the telescope itself.  I do not intend to cover all types of telescopes and mounts; I will cover the main ones that are available that have a reasonable cost.

The first and most important factor in finding a telescope is that it is only of use if it is used.  I know that sounds simple, but it is fundamental issue.  If your telescope is too hard to use, or is too heavy to move around, it is not going to get out as much and basically becomes a boat anchor or door stop.  Consequently, for a beginning astronomer, my first recommendation is that you pick a telescope that you can handle and understand easily.

One issue that inexperienced astronomers worry about is how much magnification one can get from the telescope.  Actually, magnification is one of the less important factors.  The reason for this will be described later.

There are three major types of telescopes that you will see.  Below I summarize each with some of the key advantages and disadvantages of each one.

Refractor – This is the type of telescope that you probably think about first.  It is the type of telescope that Galileo used to first see the moon of Jupiter hundreds of years ago.  You look throw an eyepiece in one end and through a prime lens (a big one) at the other end.  You can buy a decent 70mm or 80mm refractor for under $200.  You can probably buy one for less than that, but it won’t be of good quality or have a mount that is usable.  I recommend that you buy a major telescope brand like Celestron, Orion, or Skywatcher.

A refractor has the advantage of being simple.  In a small size, it is very versatile and light and can be easily transported.  A refractor can give very clear images.  However, a refractor has some significant limitations.  A refractor in the $100- $200 range will have visual aberrations around the edges of the view.  Stars near the edges will be blurry or smeared.  In addition, a less expensive refractor will have some color aberrations.  You may see color “halos” around objects, for example.  Finally, if you want more magnification (less important) and more light gathering capability (more important) you have to increase the size of the primary lens and the length of the telescope tube.  The weight of the telescope and its cost both increase quickly.  A 150mm refractor for example is already become pretty unwieldy.  Also, refractors can be built to minimize the visual and color aberrations using more complex lensing arrangements, but again, the cost and weight increase rapidly.  These types of refractors are called “apochromatic” refractors, and if you look them up on one of the telescope makers’ websites you will find prices from $500 to $1000’s of dollars for a 70mm to 80mm aperture (size of the primary lens).

As a new astronomer, it would be very difficult to justify the cost of a larger aperture refractor or an apochromatic refractor.  Most people that buy these telescopes are very deeply into astrophotography.  Having said this, I bought a very inexpensive 80mm refractor (second-hand around $100) and I use it successfully for astrophotography.  I usually must crop photos to eliminate some of the fuzzy stars on the edges, but with today’s processing software, that is easy to do.

A 70mm-80mm refractor is a decent choice for a first telescope.  What can you see with this type of telescope?  You will be able to see great views of the moon with its craters and mountain ranges.  You will be able to see four moons of Jupiter.  You will be able to see the rings on Saturn (however, they will be very small in your view).  You will be able to see the phases of Venus.  In a fairly dark location you will even be able to see a bit of some bright nebulas like the Orion nebula.

However, there are other good choices, too…

Reflector – There are various types of reflectors, but for the purpose of this article, I am talking about the most common type, often termed a Newtonian reflector.

This type of telescope instead of using a primary lens has a primary mirror at the back of the telescope.  Light enters the telescope, and this primary mirror directs the light to a smaller secondary mirror near the top of the telescope tube.  This mirror directs the light to a lens on the side of the telescope tube which is the lens you look through.  A reflector has one very clear advantage; it is easier to make a mirror without defects than it is to make a lens of the same size.  Consequently, a reflector of a give size of primary mirror will be less expensive that a refractor of the same size.  If you want more light gathering capability and more potential magnification for a smaller price, a reflector is a good choice. The quality of the image in a decent reflector is excellent.  It avoids a lot of the aberration problems of a refractor.

However, a refractor of a decent size becomes a bit hard to handle.  For example, a 200mm reflector tube is over 3 feet long!  In addition, a reflector is a lot harder to point.  For a refractor, you are looking straight at the star and so pointing is easy.  In a reflector, the lens you are looking through is pointed at a 90-degree angle to the telescope tube so getting lined up on a star is more difficult.  There are various finder scopes that help you with this (discussed in another article) but it is still more difficult.

In the section on mounts, I will discuss some additional issues with a reflector, but suffice to say, mounts are a bit more difficult for a reflector.

The main advantage of a reflector is that for the cost, you can get a more powerful telescope that gives a really nice image.  One of my first telescopes was a 115mm reflector that I purchased for about $150.  A 150mm reflector gathers about twice as much light as an 80mm refractor which means that items will be brighter and you will be able to see dimmer objects.  My second telescope was a 200mm reflector.  It was a higher quality instrument, but the images were great, and I could see a LOT more.  I bought this telescope second hand for about $300.  Compared to my previous telescope, I felt it was well worth the extra cost.

However, be aware that my 200mm reflector plus its mount were heavy.  As I got a little older, my back started complaining about it.  This setup would be much too large for a pre-teenager to handle.

A 115mm reflector of good quality would be another good choice for a telescope.  It is a good balance of portability and power but is a little harder to use than a refractor.  You will be able to see everything that you can see with the 80mm refractor and more with this telescope.  Nebulas and other deep space objects are more within your reach with this one.

Schmidt-Cassegrain – There are several types of Cassegrain telescopes but I will focus on the Schmidt-Cassegrain which is the most popular.

This type of telescope combines some of the aspects of a reflector and refractor in the same package.  An Schmidt-Cassegrain Telescope (SGT) also utilizes a mirror verses a lens for the primary element.  However, the arrangement of mirrors and lenses for an SGT are such that the viewing lens is directly in line with the direction the telescope is pointing like a refractor.  In addition, the mirrors are configured to give a long focal length (more on this in another article) in a very short package.  For example, a 200mm SGT will be about 15 inches long and still have a longer focal length that the 4-foot long 200mm reflector.  This makes the SGT lighter and much more manageable than the reflector of the same primary mirror size.  You get the same light gathering capability in a much, much smaller package.  The long focal length gives very large magnification possibility, but in my opinion, you do give up a bit of the clarity of a high-quality reflector.  An SGT is also more expensive than the reflector of the same size.  The smaller size also allows a lot better choices in the type and cost of the mount.  However, the cost aspect is not insignificant.  For a nice 200mm SGT with a good mount you will spend well over $1000.  Although the capabilities of this telescope and mount are much greater than those of the reflector, it is hard to justify it for a first telescope.  A SGT give great views and also works well for astrophotography, but if you are buying a telescope for a child (who may or may not be interested long term), of even for yourself for the first time, my opinion is that a refractor of reflector would be best.  An SGT is a great second telescope, though!

Mounts

As I said previously, the mount is as important as the telescope itself.  You may doubt that at first, but you will eventually find that it is true.  The mount is what points your telescope and keeps it pointed where you want it.  It keeps the telescope steady so that you can observe.  If your mount makes it difficult for you to find the object you want or if it shakes at the slightest bit of wind, making it impossible to see an object clearly, you will likely not use the telescope.  There are many types and makers of mounts, but there are basically two types, each with and option of having computerized control.  I will address computerized control later.  First, however, let me talk about the two main types of mounts.

Altazimuth – An altazimuth mount is your basic point and look type of mount.  The mount allows the telescope to be moved in the horizontal direction for one axis and in the vertical direction for the other axis.  With this type of mount, you can easily point wherever you want.  This is simple, direct, and easy to understand.  However, it has the weakness that to follow any object in the sky, you must move both axes.  Stars to not move directly up and down or left to right.  They are rotating in the sky so that as they move horizontally, they are simultaneously moving vertically.  This provides challenges to observing a star or object for a long period of time.

There is a special type of altazimuth mount that was designed for fairly large reflector telescopes that can be produced at very low costs: the Dobsonian mount. I won’t go into a lot of detail describing it here other than to see it is an excellent cost-effective option for a reflector telescope.

Equatorial – An equatorial mount is designed to eliminate this limitation.  When properly aligned and set up, the mount allows you to follow a star more easily once you have found the star since the mount mimics the rotation of the stars in the sky.  Unfortunately, this makes it much more difficult to get your telescope pointing at the object that you want in the first place.  A novice telescope user trying to learn how to use an equatorial mount may give up in frustration without ever having seen much!   An equatorial mount also tends to be slightly more expensive, but this is actually a minor issue.

Because of ease of use, an altazimuth mount is much more practical for a new user.  However, if the mount is computerized, the equation changes.

Computerized Control

One of the biggest difficulties for a new astronomer can be just finding what it is that you want to look at.  There are numerous sky charts available and there are also computer planetarium programs that can help, but just finding your target is a major issue that requires some study and work.  However, in recent years, computerized or “go-to” scopes have become popular, largely resolving this issue at a cost.  A computerized mount can find the object that you want to see by you just naming the object as long as the mount is aligned properly (not a simple thing to do and requires some learning and skill).  A computerized mount allows you to find things without having to be very knowledgeable about the night sky.  Even for an experienced astronomer, using a computerized mount saves lots of time and allows more items to be viewed in a single view session in much less time.  In addition, a computerized mount can “track” an object.  In other words, it can keep an object in the view of the telescope for long periods of time without the astronomer having to move the scope himself.  This is a critical capability if a person would like to do astrophotography.

Of course, the downside of a computerized mount is that they are expensive.  The most popular current computerized mount is probably the altazimuth computerized mount used on the SE series of telescopes.  To buy this mount with an 8-inch SGT telescope costs about $1500.

Bottom Line Recommendation

The final recommendation is still dependent on who the telescope is for and how much money they want to spend, but for the purposes of this article, let me assume that we are talking about a novice astronomer who has not done much if any astronomy in the past and wants to minimize the original investment.  With that in mind, my recommendation is to buy either a refractor or a reflector telescope with an altazimuth mount as a first telescope.  The choice of whether to get a refractor or a reflector depends on where you want to head in the future.  If you are going to do a lot of astrophotography in the future, there is an advantage to having a refractor since it may be of the most use for wider angle photography in the future.  However, if you aren’t sure whether astrophotography is something you are willing to spend a lot of time, money and effort on, I would recommend that for a first scope you buy a 115mm (or thereabouts) reflector with a tabletop Dobsonian mount.  This will give you the best views for the least price.  A good choice is an Orion Starblast 4.5 inch version which sells for about $270.  If you really want to go inexpensive, a 80mm Orion or Celestron refractor on a simple altazimuth mount can be had for $150 or less.  You might also investigate “seconds” at Celestron or Orion.  You can often save another 20% and the telescope will be the same except for maybe a scratch on the telescope tube which is inconsequential.

Getting Started with Astrophotography - Cameras

            First, let’s address the question, “why do astrophotography?”  The answer is that you don’t need to.  Many people never get into astrophotography at all.  It adds cost and complexity to your hobby.  It takes a lot more time and takes a lot more expertise.  But it can also be very rewarding.

            There are two main reasons why I do astrophotography.  First, by using a camera that can take long exposures, you can take pictures of things that you cannot see with your naked eye.  In a light polluted area, you can not see many nebulas, galaxies, or star clusters with your naked eye even if assisted by a telescope.  However, with a camera, you can take pictures of many of these objects, if you can get your telescope pointing in the right direction (remember, you can’t see them with your naked eye, so you must have some way of getting the telescope or camera pointed in the right direction).

            Second, it is fun to share the pictures with other people.  I am fascinated and totally blown away by things that I take pictures of, and I like to help other people have the same feelings.  More than anything else, the things that I see and take pictures of give me a much greater sense of the majesty of the universe and the guiding hand of God in its organization.

            As is the case with everything else in astronomy, you can spend a huge amount of money to build an astrophotography set up.  However, there are some things you can do inexpensively to get into this activity.

Camera

            To take a picture, you need a camera.  For astrophotography there are many choices.  Here are some choices:

1)      Cell Phone.  Yes, a cell phone can be used to take pictures of the stars!  The more capable your cellphone the better the pictures.    Even a cell phone camera can work.  You probably already have a cell phone, so this is a good place to start.  The simplest form of astrophotography is just taking a picture of the night sky without a telescope.  You can start experimenting right away.  If you want to take good pictures of planets, you will need to take your pictures through a telescope.  This can be done very inexpensively with a bracket that you can buy the connects to your telescope and holds the cellphone in the correct position.  A bracket like this will cost $10 or so.  The advantage to this approach is that it is least expensive.   It does take a lot of time and experimenting to get it aimed right and the cellphone is not quite as flexible as a dedicated camera, but you can take quite satisfying pictures anyway. One other advantage of using a cell phone (or any other one-shot type camera) is that you can change the magnification of your photos by changing the eyepiece on the telescope.  Be aware that although the next two options are much more flexible overall, they cannot change magnification, at least not without a lot of trouble.

2)      A dedicated camera designed specifically for astrophotography.  Since these are designed for the purpose, they can have several advantages.  Their cost can range from $60 for the least expensive to $1000’s for the most capable, cooled cameras.  Since I am talking about doing astrophotography on a budget, we will ignore the high-end cameras at this point.  I own a SVBONY SV105 camera that I bought for around $60.  This camera is small and easy to use.  It’s resolution of about 2 million pixels is very limited but it gives great pictures of the moon and decent pictures of Jupiter, Saturn, Venus, and Mars.  The limitations of this inexpensive camera are that it is incapable of long exposures so you can’t effectively take pictures of nebulas, galaxies and similar objects.  Also, be aware that the camera needs to be connected to a computer (usually a laptop).  It will work with about any laptop and the software doesn’t take a lot of room, so this is usually not a problem.  Finally, be aware that this type of camera must be connected to a telescope and so it is generally not useful for wide angle pictures of the sky (like the Milky Way Galaxy). As the resolution and capabilities of the camera increase, the cost increases quickly.   I recently purchased a 6.3 mega pixel camera that can do long exposure shots.  I haven’t used it yet so when I get some experience with it, I’ll write another article about that.  It cost about $399 so you can see it is starting to get a bit expensive.  One other advantage of a camera like the ones mentioned above is that they are light which helps your tracking mount function better.

3)      A DSLR camera.   This is the type of camera that has replaceable lenses.  When I was growing up, it would have been a 35mm camera, but today they are all digital which really comes in handy with astrophotography since you end up taking literally thousands of pictures.  This type of camera is expensive and normally costs $1000 or more.  However, you can save a lot of money by buying a previous generation, used camera.  I bought a Canon T3 camera on Ebay for under $100 that works great.  I was also able to get a standard 18-55mm lens with it that will not only meet a lot of your needs for wide angle astrophotography but will also serve as an excellent lens for taking great picture of your family vacations!  A camera like this provides the least expensive path to doing astrophotography of planets, deep space objects and wide-angle pictures.   The wide-angle pictures can be taken using the supplied lens.  For the planets and deep space objects you will need to connect the camera to the telescope by removing the 18-55mm lens and putting on a t-adaptor.  With this adapter, you can remove the telescope’s lens and install the camera.  There are a few other accessories that will help you in your photography that I will explain in future articles like a Bahtinov mask and a remote and controllable shutter control device, but these accessories aren’t too expensive.  Both together cost less than $50.  One of the downsides of this type of camera is that it is a bit heavy and can mess with the balance of your telescope and mount combination.  Care must be taken, or tracking will suffer.

My overall recommendation is that you can use your cell phone to experiment and determine if astrophotography is something that you will enjoy.  However, you certainly should not buy a given cell phone for this purpose.  And you can skip this step totally if you want.  If you are interested in planet photography, I would go with a cheap dedicated camera like the SV105.  Since this is only for planetary or moon photography, this does not require a tracking mount, so it gives you the least expensive approach.  But if you want to do deep space photography, or if you already have a DSLR, you might as well just start right there.  It can do the planetary and moon photography great and can also do deep space photography if you have the right mount.  Just buy a cheap t-adaptor and skip the other steps.

In my next article I will talk about mounts and how they impact astrophotography, so stay tuned for that one.

In other articles I have discussed some of the positives and negatives about astrophotography.  The biggest argument against getting into astrophotography is simply that it can add significantly to the cost.  You can easily spend thousands of dollars purchasing the equipment for a good setup.  However, I have discussed how to do this much more inexpensively.  A DSLR camera that will serve you well can be purchased on Amazon for around $100.  A adequate guidescope can be purchased for around $60.  Most people already own a laptop PC that can handle the astronomy and guiding programs necessary.  So, if you are persistent, you can build a decent setup for around $200.  As mentioned previously, this allows you to take pictures of things that you can't see with your naked eye.  While there is some romance around viewing things with your natural eyes, in a light polluted setting like the vast majority of us live in, our stargazing is extremely limited when viewing with the naked eye no matter how good of a telescope that you have.   For example, in a dark setting, I have been told that you can see the Andromeda galaxy without a telescope.  In this setting, the Andromeda Galaxy is truly awe inspiring with a telescope.  However, in a light polluted area like mine near Houston, the Andromeda galaxy is totally invisible to the naked eye.  With a moderately powerful telescope, you can see the central bulge of the galaxy and not much more.  But with a camera and the other astrophotography equipment that I have mentioned, you can pick up the spiral arms.  Another example: I have been trying to photograph all of the Messier object from my back yard.  As of July 2023, I have photographed 95 of them.  Very few of these objects are visible at all in the light polluted skies where I live.  Consequently, this project of seeing all the Messier objects that I have been diligently (and happily) working on for a couple of years, would be pretty frustrating and largely impossible without a camera that allows long exposures.  

If are going to do your observing in a light polluted area and want astronomy to be a significant hobby for you, I strongly recommend that you consider astrophotography.

Getting Started with Astrophotography – Exposure times

            There are a couple of important factors that you should be aware of when you are trying to take pictures of the starts.  One factor is that it is dark out at night.  I know, this is obvious, but it has important implications on the equipment that you need to do what you desire.  The second factor is that the earth is rotating so the stars appear to move in a circle around the north celestial pole (a point corresponding to the spot directly above the north pole.  It is near to the star Polaris, but not exactly).  This movement is slow enough that you can’t really see it immediately, you can easily verify by picking out a star and noting its location and then coming back outside in an hour or two and seeing that it has moved to a slightly different location.  This is important because while you need longer exposure times to gather light in the dark night, the star move enough that the picture becomes smeared.  You get star trails in your picture like in the picture in my "pictures I have taken" section entitled "star trails".    (I didn't take this one, I found it on line.  When I take a picture that has star trails I normally delete it)

Note that the stars instead of being perfect points of light are elongated.  This is because the star moved during the time that the shutter was open.

            There is a simple rule of thumb that can help you calculate how long you can leave the shutter open on your camera before you will get significant star trails.  Although it is not perfect, it will put you in the ballpark and it is all many astronomers ever use although there might be more precise calculations.  The calculation is as follows:

                            SS=500/(cf*fl)   where SS = maximum time shutter can be open

                                                                     cf = crop factor

                                                                    fl = focal length of the lens you are using

            You may not be familiar with the term crop factor, but it is simply a factor that relates current cameras with chips to cameras in the past that used 35mm film.  If you have a DSLR you can just use 1.6 as the factor and it will come out all right.  In fact, if you have a different type of camera, you can still use this factor and it will be pretty good.

            Focal length has to do with the lens that is used.  If you are just using a camera lens, the focal length will be stamped right on it.  The lens that comes with most DSLR’s is a 18-55mm lens which means that you can have it on 18mm (all the way zoomed out), 55mm (all the way zoomed in) or anywhere in between.  If you are connecting a camera directly to a telescope, the focal length becomes the focal length of the telescope (you can find this printed somewhere on your telescope or in its documentation).  For example, a simple refractor might have a focal length of 500mm.  A Schmidt Cassegrain telescope may have a focal length of 2000mm.

            Let’s see how this affects the exposure time limit for various situations.  First, let’s consider your camera set at the 18mm focal length (minimum zoom).  The equation gives us:  SS=500/(1.6*18) or maximum exposure length is 17 seconds.  That means you can leave your shutter open for 17 seconds and not get star trails.  That’s enough exposure time to pick up all the stars you can see with your naked eye plus some additional ones.  This is not long enough to allow detailed pictures of deep space objects, but it is long enough to take some satisfying photos of the stars.

            If you set your lens to 55mm (maximum zoom) the same equation would be: SS=500/(1.6*55) or maximum exposure length of a little less than 6 seconds.  You will still be able to pick up the stars you can see with your naked eye, but not too much more.

            Now, let’s look at what happens when you attach the camera to a 500mm focal length refractor telescope.  The same calculation results in a maximum exposure length of less than 4/10 of a second.  Fortunately, the main lens of the telescope has a larger diameter than your camera lens did which means that it can capture more light, but you are still very limited on exposure time without star trails.  If you are trying to photograph a nebula, a galaxy, or a dim star cluster, this is not going to make it.

            Finally take the case of the SCT.  Applying its 2000mm focal length to the equation tells us that our maximum exposure time is less than 1/10 of a second which is very limited and not sufficient for deep space objects.

            So, what do we do if we want to photograph dim deep space objects?  We need longer exposure times.  But to do it without smearing the stars in your picture, it will be necessary to mount our camera and/or our telescope on a mount that will “track” the stars.  This means that the mount moves with the stars and keeps the target of our photography centered in the camera view so that it appears not to move. This will be discussed in the next article about mounts.

Using a Reflecting Telescope to take Photographs

Connecting a camera to a Schmidt Cassegrain telescope is easy.  The scope and connection are sturdy, can easily support any camera, and focusing is not a problem.

The same can normally be said for a refractor telescope although you may have to experiment a bit with your focuser and whether the diagonal is needed or not to be able to get the camera in focus.  Also, inexpensive refractors may not have a sturdy enough focuser to hold the camera stiffly and you may lose your target temporarily when you put the camera on although you can eventually get it pointing in the right direction with a little effort.

However, a standard Newtonian reflector that is configured for visual observation can be a challenge.  For my original reflector, it was impossible to get the view in focus with my DSLR camera attached.  The problem is that the focus point of the telescope is such that you can’t move the camera close enough to the telescope with the focuser to get it in focus.  Basically, the distance between the front of the camera where it connects to the telescope and the sensor in the camera itself is too long to allow focus.

There are a couple of solutions to this problem.   The first is to get a camera that is designed for use with a telescope.  Generally these cameras have the ability to insert the camera in such a way that the sensor is much closer to the beginning of the focuser than a DSLR camera.  In fact, some of these cameras can actually fit inside the focuser in such a way that the sensor is essentially even with the end of the focus tube or even inside it.  Focus is therefore possible.  Of course this means the purchase of a new camera, and a dedicated telescope camera with a similar resolution to a DSLR can cost in the $1000’s.  You can buy a decent telescope camera like the Orion Starshoot mini 6.3, but you will never get the quality of pictures that you can get with the DSLR.

If you don’t want to spend money on a new camera, there is another solution.  One common piece of equipment that most telescopes come with is a Barlow lens.  The Barlow lens is normally used to increase the magnification of a given lens, but it also shifts the focus point of the telescope enough that a DSLR camera can be brought into focus.  Even if you don’t have a Barlow lens, you can buy one very inexpensively (under $20).  There is one caveat – the Barlow lens does increase the magnification, so your camera will now cover a smaller field of view.  If you are trying to photograph a large deep space object like Andromeda Galaxy, this could be a problem since you might not be able to get the entire galaxy in frame with the Barlow lens.  But in most cases the extra magnification will not be an issue.

Note that there are reflectors that are designed for astrophotography.  I haven’t used one but I understand that these reflectors are manipulated such that the focus point is conducive to the use of a DSLR type camera.  They are also usually much shorter focal length than their visual counterparts of the same aperture.  This facilitates deep sky photography, giving a bigger field of view, but, of course, yields a lesser ability to magnify objects.

The bottom line is that there is a way to make your reflector work for astrophotography, but it may take a little work and experimentation.

Getting Started with Astrophotography - Mounts and Tracking

As mentioned in the last article, if you limit your exposure time for a picture, you don’t need any special mount to do it. However, the more magnification you use, the less exposure time you can have before getting star trails. One of the neat things about astrophotography is that by using longer exposure times, you can see things clearly in the picture that you cannot see with your naked eye even with the help of a telescope. To take exposures of the stars using longer exposure times, you need to be able to follow the stars while the shutter is open. A proper mount can do this for you. However, as is the case with everything else, the more precise your mount, in other words the more exposure time you can effectively use, the more expensive the mount will be. Also, if you want to use a telescope for these large exposure pictures, you have the added complication of needing the mount to be able to handle a heavier object. The more weight that a mount will handle, the more expensive the mount. A very precise mount that will handle a telescope of reasonable size can easily cost upwards of $10,000. So, with all this in mind, let’s look at the various options that are fairly inexpensive.

Tracking mounts for cameras and very small telescopes

If your main interest is wide angle views of the night sky, you can do it with your DSLR camera with a mount that can handle up to 2 pounds or so. This will give you good pictures of the Milky Way or broad patches of the sky. If you want pictures of distant galaxies or nebulas you will need some magnification and so the wide-angle pictures you get with your camera and a simple camera lens won’t work. But wide-angle pictures can be stunning and this is certainly a good place to start.

There are numerous mounts that are excellent that will handle your camera without a problem. I won’t review the different ones since I haven’t used them. However, in general, a computerized mount of this type is going to cost $500 or so. However, there is a less expensive option available that will get you started for around $150. This is the Omegon Mini-track mount. The version I have is the LX2. I think they are selling the LX3 version now although it is very similar to the version I have so my comments should be valid. This mount is an ingenious mount that uses no power supply at all. It is basically a clockwork mechanism. You mount the mechanism with a supplied ball type mount head for the camera on a standard camera stand. You align the mount to the north star using a supplied finder scope and then point the camera in the direction you want, wind up the mechanism and start taking exposures. It is good to have a remote shutter controller to operate the shutter to prevent movement of the camera when taking a picture. The mount will track the sky for about 60 minutes with no problem. I have found it to work quite well with exposures up to two minutes or even more. The downsides of this inexpensive option are: 1) the mount and mechanism handle only up to about 2 pounds. (note: the literature on the mount says 4 pounds, but I think that is stretching it) The camera body takes up a lot of that weight with the lens taking up more weight. Telephoto lenses weigh even more so you can’t get too much additional magnification that way, and an additional telescope is pretty much out of the question. 2) The mount is NOT computerized. You must know where your target is in the night sky. Since you may not be able to see what you want with the naked eye, it may take a bit of trial and error to get what you want in the picture. However, since your pictures using this setup are by nature wide-angle, you don’t need to be overly precise in your pointing, you just need to know the right direction to point.

Going to a $500 computerized mount will make pointing easier and it will likely handle significantly more weight - perhaps enough for a very small telescope and a light dedicated camera - but in my case, I could not justify ever doing this because of other options that exist as you get better and better base equipment for your telescope.

Tracking mounts for telescopes

Computerized mounts make astronomy a lot easier as has been mentioned in a previous article. Finding objects in the sky is vastly simplified by having a set up like this. Depending on the weight capacity and precision of the mount it can cost $10,000 or more. However, there are decent computerized mounts that are much less expensive. Probably the most popular and cost-effective telescope and mount combination that is available is the Celestron Nexstar series. The least expensive model is the Celestron Nexstar 8se. This is probably the easiest computerized mount that you can use, and it works very well although it has some limitations. The mount with the 8-inch Schmidt Cassegrain telescope currently costs around $1500 although prices are currently a bit inflated due to supply/demand issues related to COVID. I bought mine before the pandemic for around $1200. The mount is an Alt-Azimuth mount which is the source of its simplicity and its limitations. Although this set up will track stars, to do so, it has to move both axes simultaneously. This adds some variability in the tracking. Also, since the telescope is not rotating exactly with the night sky, the object being viewed will appear to rotate over time. This is not a big problem for most items that you want to track given the other limitations of the mount that I will discuss, but if you are trying to take a video over a long period of time of a planet like Jupiter, the planet will seem to rotate. This makes planetary photography limited. This can be mostly rectified by adding a “wedge” to the system which costs about $250. However, even with a wedge, my experience is that exposure times are limited to about 15 seconds. This amount of exposure time with the greater light gathering capacity of the 8-inch telescope allows you to take great pictures of star clusters or bright nebulae. Most of the pictures on this website were taken with this set up.

One thing that you can do with a set up like this is to add a small bracket to the telescope that can hold a camera. My daughter made one of these for me for less than a dollar with a 3D printer. With a camera mounted on the telescope, the mount will track your target and you can take much longer exposure pictures with the camera while you are either using the telescope for visual observing or even for taking photos through the telescope at the same time. Because of the smaller focal length of the camera’s standard lens, you can do exposures of 1 minute and more.

Overall, my recommendation is that a telescope like the Celestron 8 SE is a good place to start your astronomy hobby if you are willing to invest the initial $1200 or so. It gives you a flexible platform to start with. I would, however, forgo the purchase of the wedge as it doesn’t give you enough extra capability to justify the expense.

One more word before I go on; always keep in mind that astrophotography has two major variables that need to be considered. First is the focal length of the lens or the telescope which gives you magnification. Second is the light gathering capability of the device you are using. The bigger the primary lens, the more light you can gather. The human eye has a primary objective diameter of about 7mm. An 8-inch telescope has a primary objective diameter of 200mm. A telescope can therefore gather something like 800 times as much light as the human eyes (compare the areas). The issue is that with the larger objective diameter you usually get longer focal length, which gives you greater magnification but also reduces the amount of exposure time you can use (see the rule of 500 in the previous article).

The next step up is to have a computerized German Equatorial Mount (GEM). Before I go on, let me just say that a GEM that is not computerized will likely be very frustrating for a beginner and will result in the telescope being put in the closet and never used. If you don’t have a computerized go to mount, an alt azimuth mount is much easier to use. A GEM is designed to follow the night sky as it rotates around the north celestial pole. This simplifies tracking making it easier to build a decent mount at a reasonable cost. A decent go to GEM mount will allow you to get longer exposures than you could otherwise. How long? It depends on the focal length of your telescope and the cost and precision of your mount. Since we are talking about minimizing cost here, let me discuss only the least expensive GEM mounts. The lowest cost GEM mount that will handle a telescope such as a Celestron 8SE with a camera attached is the Celestron AVX or the Explore Scientific EXOS-2GT PMC8. I recently purchased the Explore Scientific model for $999. I am still working on becoming proficient at using the mount, but so far, I have been able to achieve exposures of over a minute without much trouble with my 8-inch SCT. I expect that with my simple refractor with 400mm focal length, I will easily get several minutes of exposure time without guiding (note: I’ll talk about guiding in a different article). These exposure times allow me to get more of the nebulae than I could get before. Consequently, I will be going after deep space objects that I was unable to see before I got this mount. Just as an example, my first attempt at photographing the Orion Nebula with this mount is shown in the “Pictures I have taken” section labeled, “Orion ES mount”. As you can see, more of the cloudy nature of the nebula is visible.

Probably the most popular GEM mount is the SkyWatcher HEQ5 or the essentially equivalent Orion Sirius EQG (made by the same manufacturer, look the same, too). These mounts sell from $1300-$1500. The Celestron AVX, Skywatcher HEQ5 and Orion Sirius EQG all use small motors attached to gears to move the mount on its two axes. More expensive mounts use belts between gears that decreases gear backlash (gear backlash is caused by the fact that gears cannot mesh perfectly and so there is a small amount of play resulting in the mount not moving immediately when the motor starts which can cause tracking problems). The Explore Scientific model that I have is the least expensive model on the market that uses belts to drive the mount which is one reason I chose this mount. I can’t really say if it makes it better at tracking or not at this point. The other difference between the Explore Scientific and the other three models is that the other models use a hand controller to drive the mount. Explore Scientific has a box that allows the mount to be controlled via a computer, tablet or smartphone. I find this approach to be a bit less straightforward than the hand controller and it took me longer to learn how to use it. Explore Scientific claims that this approach lets the mount use other software or to be ungraded more easily. This may be true, but it is not something I have verified or been interested in yet. I may change my mind on this, but at this point, I would not look at this as an advantage – the hand controllers are easier to use.

For an ultimate recommendation on a GEM mount, I am a bit uncertain at this point. I need more experience with my mount. Hopefully, I will be able to update this article sometime in the future with a solid recommendation. The one thing I can say at this point is that a GEM mount is harder for the novice to learn to use, so be cautious in buying one until you get a bit of experience with astronomy!

Some other camera considerations – pixel size and field of view

When you connect a camera to your telescope you may be surprised at how magnified the picture seems to be and how small a field of view you have. Field of view is basically the area of the sky that your picture covers. This is especially and issue if you are trying to use a telescope with a long focal length. For example, my Celestron 8SE telescope has a 2032mm focal length. Using my Canon T3 SLR, I can only get about a third of the Andromeda Galaxy in the frame! This is one of the reasons that a lot of deep sky astrophotography is done using smaller refractors with short focal lengths. However, this means that the telescope does not gather light as effectively as a larger scope and so you need to increase exposure times to see the same thing. In addition, not every electronic camera is the same. Even two DSLR’s can have significantly different field of view.

The best approach is to experiment with the cameras that you must determine which will work out best for you. Once you know what one camera really does, it is a lot easier to determine what type of camera (or telescope) you should get next. This article will not cover all the aspects of this issue but will give you some things to go on.

Two of the most critical factors that electronic cameras have that influence their performance in astrophotography are characteristics of the chip that is used: 1) the number of pixels determines the resolution of the picture and 2) the size of the pixel has a significant influence on the field of view (how much you can get in the picture.

Number of pixels

The number of pixels is always specified for a camera. A simple planetary camera like a SVBONY SV105 has around 2 million pixels or 2mp. A new DSLR camera like the Canon T7i will have a resolution of over 24mp. Note that 24 mp is not necessarily 12 times better than 2 mp. Note that if a camera sensor is square, then the square for a 2mp camera is about 1400 pixels on a side while that for a 24 mp camera is about 4900 pixels on a side or about 3.5 times the other camera. To give you an idea of the differences between cameras, let me compare the three cameras that I have: a 2mp SV105 camera, a 6.3mp Orion camera and a 18mp Canon T3. For objects such as the moon or Jupiter, the 2mp camera produces adequate pictures. Using the 6.3mp camera, pictures of the moon do show additional detail, but not amazingly so. I haven’t used the 6.3mp camera on Jupiter yet, but the 2mp camera yields limited detail of the clouds and I expect the 6.3mp camera to be significantly better. Pictures taken of the moon with the Canon are very sharp but not that much better than my 6.3mp camera. Pictures of Jupiter with the Canon are clearer than those with the 2mp camera, but you give up some magnification as I will discuss below. I believe that the 6.3mp camera will be a good balance of magnification and detail. I will report when I am able to take some pictures with it.

Summarizing, the more pixels the better, but don’t expect pictures with a 24mp camera to be 12 times better than those taken with a 2mp camera!

Pixel size

Pixel size is usually show in the specification for a camera but not in the advertisements, so you must look for the data. The smaller the pixel size, the smaller will be your field of view and the larger will be the apparent magnification. Comparing my three cameras from above; the SVBONY 2mp camera has a pixel size of 3 micrometers, the Orion 6.3mp camera has a pixel size of 2.4 micrometers and the Canon T3 has a pixel size of 5.2 micrometers. The field of view is approximately inversely proportional to the pixel size. More simply, smaller pixels give you a smaller field of view which is a larger apparent magnification. If you are taking a picture of Jupiter and want a lot of detail of the clouds and the great red spot. You want small pixels and a lot of pixels. However, if you want a picture of the moon, small pixels may not allow you to get the whole moon in the frame with your camera and telescope. If photographing the Andromeda galaxy, which covers about 6 times the stretch of the sky that the moon does, small pixels may not be good for you at all!

The best way to show the impact is with some pictures. In the section on “Pictures I have taken” I will post three pictures of the moon next to each other and label them with the camera chip parameters; ‘2mp 3micron’ for the SVBONY, ‘6.3mp 2.4micron’ for the Orion, and ‘18mp 5.2micron’ for the Canon.

In summary the smaller the pixel the smaller the field of view, consequently, it is hard to use a camera with very small pixels together with a telescope with long focal length.

The Best Camera, Telescope, and mount for the Job

What is the best telescope, camera, and mount combination to do what you want to do? The answer depends on what you are trying to take a picture of and what you want the picture to show. This website is focused on doing that for a reasonable cost, so that will be a prime consideration in the information that follows.

From a camera standpoint, a DSLR camera like a Canon T3 (or any of the newer versions) are the most flexible cameras that can be used. They tend to have better resolution than inexpensive built for purpose astrophotography cameras and can be adjusted to many different settings to optimize the photo. Some astrophotographers modify their cameras to make them more sensitive to the parts of the light spectrum that they want and less sensitive to the parts they don’t want. But that makes the camera less useful as a day-to-day camera that can be used for other things and adds additional cost, so that won’t be considered here. But a DSLR with a remote shutter timer connected is a very good way to do astrophotography of many types. On the negative side, DSLRs tend to be a bit heavy, requiring larger mounts to handle the telescope/camera combination. Built-for-purpose astrophotography cameras like those sold by companies such as ZWO, can range in cost from $60 to well over $1000. On the lower end you get less resolution and less ability to control exposure. On the upper end you get a lot of resolution and camera cooling that decreases the noise in the picture, but with this, the camera begins to be much heavier, like a DSLR. I have found a decent sweet spot in between the two with a 6.3MP Orion Minishoot camera that allows longer exposures and is very light. You give up some resolution versus a DSLR, but most mounts will handle the telescope/camera combination easily.

In the last article I talked a lot about field of view, and I won’t repeat that here, except to say that for taking large swaths of the sky (like a shot of a large section of the Milky Way) you need a DSLR without a telescope. A cheap tracking device can help to get better pictures, but in a dark location, decent pictures of the Milky Way can be taken with just a stationary tripod. If you want to take pictures of distant galaxies like Andromeda, you will need a telescope (usually a refractor) with a short focal length (around 500mm), a good tracking mount and either a DSLR or a built for purpose astrophotography camera. This set up is also good for pictures of nebulae. If you want to take pictures of the moon and the planets, a long focal length telescope (like a Schmidt Cassegrain at 2000mm or so) will give you impressive pictures although you can also take successful pictures with less magnification using the previous set up.

From a mount standpoint, the greater the apparent magnification of your telescope/camera combination, the better the mount must be at tracking. Using a long focal length telescope without a tracking mount will only allow you to take pictures that have exposure lengths of less than a second (the moon and a few planets.

This may all sound confusing but let me put it all together in a diagram. (See Telescope/Camera/Mount spectrum in "Pictures I have Taken")

To get the best pictures, you need to be as close to the center of the telescope, camera, mount combination as possible. For example, if your desire is to take pictures of dimmer nebulae and galaxies, the short focal length telescope with tracking mount is best (black line). For planets and star clusters, the longer focal length telescope with tracking mount is best (blue line).

Sorry, but there is no good one answer for everything. However, you can cover a lot of the possibilities with two telescopes, one good camera and a good mount. My combination is an 8 inch Schmidt Cassegrain at a focal length of 2032mm for taking the moon and planets and smaller deep sky objects with a cheap ($100) refractor with a focal length of 500mm for taking pictures of larger galaxies and wide angle shots. I use both an Orion 6.3mp Minishoot camera and a Canon EOS T3 although either one will work fine as long as your mount will handle the weight of the DSLR. I have two mounts, a alt-azimuth go-to mount that came as part of my Celestron 8SE package and an Explore Scientific EXOS 2GT PMC (German Equatorial Mount). The Celestron mount gives me exposures of up to 15 seconds or so before I get star trails while the Explore Scientific can give you significantly higher exposure times. If I had it to do all over, I would probably have bought the Celestron Schmidt Cassegrain with a German Equatorial mount although I have to say that the Alt Azimuth mount is much easier to use so that has to be considered if it is your first purchase.

Messier objects

Charles Messier was a French astronomer of the late 1700.  He was mainly interested in finding comets. In his research he often found objects that were confusing.  They were not comets, but they weren’t stars either.  He began a catalogue of these objects.  These objects are star clusters, galaxies, nebulae and other deep space objects. 

This list eventually included 110 objects visible from the Northern Hemisphere.  This list is popular with amateur astronomers, especially those that are interested in astrophotography.  Since the list was originally developed in the late 1700’s when there was little light pollution, it includes many objects that are very faint and therefore much more difficult to find in our light polluted world of today. 

However, as an amateur astronomer’s skills improve over time, he will be able to photograph more and more of the messier objects.  It is a good challenge and helps an astronomer gauge his improving technique.

There are a few messier objects that are visible to the naked eye, even in cities, such as M45, Pleiades.  Other objects are 11 magnitude or so and require a large telescope and good technique to capture. 

In my first couple of years as an amateur astronomer, I have captured over 60 of the objects.  It is a challenge, and it is fun to do, but it takes a lot of patience since the dimmer objects require good viewing conditions such as a night with the new moon to capture. 

As you start your journey as an astrophotographer, you will likely take the challenge of photographing as many messier objects as you can.   I found a good chart that will guide you on your way by indicating the relative difficulty of photographing each object.  I have included a copy of the chart in the “Pictures I have taken” section under the title of “Messier Objects”.  I hope that this will be useful to you.

For reference, although I live in a highly light polluted area of the country (bortle 6) I have had little difficulty photographing any of the items identified as Very Easy, Easy or Moderate.  I have successfully photographed a few in the Hard category and have been successful so far only photographing one of those in the Very Hard Category.  As of October 2022, I have successfully photographed 75 of the Messier objects.

Guiding

On my next step in my astrophotography journey, I decided to try guiding.  Guiding is using a small telescope piggy-backed on the main scope to improve tracking and to allow longer exposure times. In subsequent articles I will give details on the nuts and bolts of this, but in this article, I want to recount my initial experiences and how it might relate to your choices on telescopes and mounts.

I was initially a bit reluctant to try guiding since I thought it would be difficult and since it requires another piece of equipment.  However, due to some difficulties that I was having with my Explore Scientific Exos II PMC8 mount, I thought that guiding might help me resolve some of those issues.  It turns out it didn’t, but my foray into guiding was well worthwhile.

Let me digress a bit at this point and talk about my problems with my ES Exos II PMC8 mount.  This mount is very appealing due to its reasonable cost and significant capabilities.  But there are some problems that you may or may not encounter.  The first issue was getting the mount to be reasonably accurate in finding objects in the sky.  Following the instructions given in the user’s manual, I was very disappointed in its “go-to” accuracy.  Explore Scientific provides decent customer service (they actually try to respond to your questions in a timely manner) but after several exchanges, I had not solved the problem to my satisfaction.  I was eventually able to get decent performance after a lot of trial and error.  The second problem was that there were some minor mechanical problems with the mount that showed up.  The customer service was able to step me through the process for fixing it, but it did require taking stuff apart, so if you are not comfortable with doing that, this may not be a good choice for you.  The third problem is that the mount operates by Wifi.  You basically give commands using a computer or tablet connected by wifi.  This on the surface seems handy, not being tied down to the cords that handset controllers have for most mounts.  However, I have had a lot of problems with the signal dropping out.  When the signal drops the mount stops functioning and you have to reboot and start from scratch.  I suspect that a lot of the problem is that living in an urban area I get interference.  The mount can be set to operate on 16 different channels to try to avoid interference but changing the channel is not a quick easy process.  I have tried 3 channels so far and haven’t found one that works consistently.  Hopefully I will eventually find one that works, but it had been extremely frustrating, so again, you may want to consider a mount with a wired controller to avoid the issue (note: you can make a direct wired link from your computer to the mount, but you have to install special software and go through a number of steps to accomplish this – I haven’t tried this yet).

Move to the issue at hand, guiding.  I purchased the small telescope I needed for guiding with all the mounting equipment for about $50.  The software for guiding is free (it is called PHD2).  I already had a planetary camera which is perfect as a guide camera (see my article on cameras).  I was surprised at the relative ease with which I got guiding up and running.  I was successful on my second attempt.  My first attempt was unsuccessful I believe because I didn’t read all of the instructions carefully, but I also had the communications problem with my mount pop up and a gave up for that night.

To eliminate at least one possible problem, I decided to try guiding using the mount from my Celestron SE8 that has a hand controller and hence no communication issues.  With this issue out of the way, I pretty quickly figured out what I had been doing wrong the night before and was guiding somewhat successfully. 

Here are a few very early conclusions from the first two nights of guiding:

1)      Guiding is not nearly as hard as I thought it would be.

2)      Guiding allows you to get much higher exposure times.  I was able to do 45 second exposures with my 8-inch SCT where without guiding, I could only go to about 13 seconds consistently.  I might be able to go even longer.

3)      The documentation that I read for my set up said that a mount that is not a German Equatorial Mount will top out at about 45 seconds of exposure time due to rotation issues that exist for a non-GEM type mount.  However, I have a wedge which theoretically solves this problem.  In a previous article I said that a wedge wasn’t worth the cost.  But with guiding, that may be incorrect.  With wedge and guiding, I can get good enough exposure times to photograph most Messier objects, even in a Bortle 8 environment (lots of light pollution).  Consequently, a Celestron SE8 type set up with wedge and guided is a low cost and acceptable approach to astrophotography.  Had I discovered this earlier, I probably would have delayed my purchase of a GEM until I had fully explored the capability of SE8/wedge/guiding.

4)      The PHD2 software also gives you a visual way to see what affects the mount’s ability to track a star.  You can see the impact of wind, of touching the mount and of adding some other element onto the mount.  Good astrophotography depends on controlling these factors.

In summary, I am very happy with my first foray into guiding.  I am excited to see what happens when I successfully guide my GEM.  I will update this article as more information becomes available.

After several exchanges with the users groups that deal with the Explore Scientific mounts, the same resolution kept coming up to resolve the communication issue, and that was to provide a hard wire connection.  This mount was clearly designed to be used wirelessly, so this is contrary to what the makers intended, but at least for me in this urban setting, I finally decided that there was no choice.  It took me several days to get all of the necessary actions identified to make the switch but I was finally able to make the hard wired connection successfully.  Since doing that, I have had much better experience with the communications with the mount.

However, this change came at a cost.  As I mentioned, the mount was designed to be used wirelessly and the software (ExploreStars) that drives the mount's go-to functions DOES NOT WORK with a wired connection.  ExploreStars also is the program that helps you align the telescope in the first place, so it is pretty important to have this function.   Anyway, in the wired case, you need some other program to interface with the mount and the computer to provide a go to function and to provide for alignment.    One program that seems to be popular in astronomy circles is called Stellarium.  Apparently this works well for mounts that utilize a hard wired hand controller, unlike the ExploreScientific's Wifi approach.    I installed it on my computer, but after many attempts at making it work, I got very frustrated and set it aside.  The program would only work sporadically and made the situation much worse than when the communications was bad.  I asked the forums if anyone has found a better program to use and no one has answered so I don't think my problem is unique or that there is a really good solution at the present time.  One would only hope that eventually Explore Scientific will go through the trouble to make Explorestars work with a wired connection, but until then this is a definite weakness.

I did find a workaround for my purposes though.  Since my basic desire in this whole effort was to achieve good guiding and since the PHD2 program used for guiding does work well with the wired connection and the mount's driver, all I needed to do was get the telescope pointed in the right direction and then turn on PHD2 in order to guide.  Easily said, but not perfectly simple.  The first step in doing this is to achieve a decent alignment of the mount.  To do this, I do a north polar alignment.  This is purely a mechanical process using a small polar scope that comes with the mount.  Once this is done, I hook up my mount to its driver and to the Device Hub program in ASCOM which gives me a virtual handset.  This program also has a function that allows the operator to directly input the RA and Dec values for an object and then slew to it.  So what I do is input the values for an object I can see and am familiar with and then have the program slew the scope to that location.  Then, using my red dot finder, I physically adjust my mount in the Dec and RA directions to get the mount pointed exactly at the object that I picked (note, this is a mechanical adjustment, no software involved).  I then further center the object by looking through the telescope, or in my case by turning on my camera and centering the object in its screen.  Once this is done, the mount is reasonably well aligned as long as your mount is level.  Then you can input  the coordinates of whatever object you want to photograph into the virtual hand controller and slew to it.  Once i slew to the desired location, I turn on the PHD2 program, connect it to the mount and the drivers and it will begin to guide.  

This process has been very successful in allowing me to photograph whatever object I want.  It is a pretty manual process.  I have to look up the coordinates of whatever object I want to find and manually enter them, but there are lots of programs that can give you coordinates (I use SkyPortal on my mobile phone to do it, for example).

Someday, I hope to find something that will do all the work automatically for me, but for now, I at least can do what I want to and it has allowed me to begin to evaluate if the Explore Scientific GEM belt driven mount has any advantages over my original Celestron SE8 Alt-Azimuth mount with a wedge.   I will learn more as time goes by, but this is what I have learned so far:

When guiding, the Explore Scientific is able to keep the mount pointed at the object of interest with much less variability and smaller adjustments.  The PHD2 program has a graphic that shows the ongoing adjustments that the program is making to the mount and how far the deviation from the target is at any given moment.  The ExploreScientific mount generally has less than half the exhibited variability as compared to the Celestron mount based on my observations.

But the important question is this:  is the easier to use Celestron setup "good enough?"  The answer to this question is more nuanced.  It depends on what you are trying to do.  With the Celestron set up I can get exposures with my 8 inch SGT with 2032mm focal length of 30-45 seconds so far.  This is good enough for many uses, certainly most that a new amateur astronomer would attempt.  But, to get the 1-2 minute exposures that you hear about, the better guiding performance of the Explore Scientific mount will be useful.

Finally, let me reiterate that the Celestron set up is easier to use and in my experience has considerably less bugs and frustrations, but the Explore Scientific seems to be more capable.  The cost of the two set ups can be pretty much the same, so any decision should be based on your objective, the time you have available and the level of patience that you have.  For a first time user, my belief is that the Explore Scientific will represent more of a challenge than most individuals are up for and it could quite possibly end up in the closet as an expensive paperweight.  On the other hand, if you really get into astronomy, you will eventually have a desire to go to a GEM.  Celestron, Orion, Skywatchers and other companies make GEM mounts with hard wired hand controllers, but right now their least expensive are generally $300-$500 more expensive than the Explore Scientific mount, and I can't evaluate whether they will control as well (these mounts are not belt driven.  To go to a belt driven mount from these companies you are talking considerable extra cost.  The Explore Scientific is without a doubt the least expensive belt driven mount)

Finding a Mount Controller, Planetarium Program and Guiding Program That Work Together

             In a previous article about guiding, I described a simple way to do guiding using PHD2, ASCOM Hub and the Explore Scientific driver for my Exos-2 mount.  What I documented there works, but it is a bit inefficient.  Ideally one would like a planetarium program to move the telescope to whatever target you choose.  I tried to use Stellarium which is probably the most popular free planetarium program out there.  What I found was that in order for Stellarium to take control of the mount, the ASCOM Hub had to be shut down.  Apparently, there are conflicts in how the two programs try to control the mount.  The problem with this is that to use PHD2 for guiding, you must have the ASCOM Hub up and running.  Consequently, I was using Stellarium to find my target and then once it was found I would  shutdown Stellarium, start up ASCOM hub and then start up PHD2 for guiding.  If at some point I wanted to go to a new target, I had to shutdown PHD2, shutdown ASCOM hub and restart Stellarium.  It should also be noted that to run Stellarium, you still have to start up ASCOM hub first so that you can unpark the mount – Stellarium can’t do it on its own.  I know this sounds confusing, and it is.  It was also very frustrating to have to start up and shut down programs.  What is even worse is that every time you shut down PHD2 and restart it, the program goes through its calibration process which takes 5 minutes or more.  The bottom line is that using Stellarium with the other programs was just about as inefficient as not using it at all.

             I went on the astronomy chat boards and asked if anyone had a solution.  I only received one comment back and it really wasn’t a direct answer, but it did mention a planetarium program called Carte du Ciel that seems to work with ASCOM Hub.  It is also a free program so I loaded it up to see what it could do.  After spending about an hour to get it configured and to test everything out, I had my solution!  You can have your mount driver, ASCOM Hub, Carte du Ciel and PHD2 all running at the same time and they work fine.  No more starting up and shutting down programs, and no more multiple calibration events for PHD2.  With all these programs working together, it is possible to move from one target to the next and guide on each target very efficiently. 

             Carte du Ciel is a very capable planetarium program.  Its only downside is that its graphics are not nearly as nice as Stellarium.  But that is a small price to pay for the functionality that it allows.

Another Issue to Consider – Time

The two greatest obstacles for a beginning astronomer are 1) having the right equipment and 2) having the time to spend.  Several other articles have addressed the first item in detail.  In this article, I want to address the second.

Some new amateur astronomers have the idea that they are going to be able to observe miraculous things on the first night out.  If they do not have a goto telescope, the first thing they must do is be able to find their targets.  It takes some skill to do this.  Other than the moon, most beginning astronomers don’t know where to look. 

Because the moon is so large and so bright, it is easy to find it and view it right away.  The moon is a good first night target. 

After the moon, the planets, specifically Venus, Mars, Jupiter and Saturn are the next easiest since they are bright.  But they move around, and you need some type of astronomy program like Stellarium or Skyportal to tell you where they are at any given time.  Even with those programs, it takes a new astronomer some time to get oriented to the sky to be able to find things. It takes some time and effort and if you are unwilling to put in a few hours studying and a few more hours just looking at the night sky and trying to find key stars and planets, then don’t spend the money on a telescope!  It will just end up in your closet.

If you went to the expense to buy a goto telescope, you may have thought your troubles were over.  Unfortunately, learning how to operate such a telescope and learning how to align it for use take some study and effort.  Once you have put in the time, the telescope will be much more fun to use.  However, most inexpensive goto scopes may not be perfectly accurate so you still need to develop good adjustment skills. But after putting in the time to gain these skills, visual observing becomes a treat and you will find yourself outside quite often.

The next step for a new astronomer is often astrophotography.  Astrophotography represents a challenge and more time investment, but due to the ability of a camera to gather much more light than your eye with longer exposures, you are able to see much, much more in the sky.  The universe of galaxies and nebulae can open up to you and bring even more interesting things to your view.

Once you start to photograph deep sky objects, it won’t be long before you want to do more and even better.  This often means getting a better mount, a GEM type mount.  In another article, I talked about my trials with a new mount and the many hours it took before I was able to consistently use it.

The next step for many new astronomers is to start guiding to get longer exposures.  As I discussed in another article this requires a bit more equipment and with that new equipment there is more time learning how to use it effectively. 

In my astronomy progression, this is where I am at.  It has helped me to get better pictures.  Note some of the latest pictures that I have posted in “Pictures I have taken”.  For example the picture of M8, the Lagoon Nebula.  I am now able to get a much clearer picture and more of the nebula than I was able to get a year ago.

This progress is not without cost, however, even on an ongoing basis.  To set up my telescope, start up all the software, align correctly and so on now takes about 30 minutes before I can take my first picture.  In Texas where I live, it doesn’t get dark until well after 9 PM so this means that it is almost 10 PM before I take my first picture.  During the summer, you basically have to stay up late to do much astrophotography.

In summary, each step along the way of doing more and more with your telescope takes more and more time.  It is worth it, but if you are impatient, it can cause you a lot of stress.  Be prepared.

Another Useful Tool

I recently found another useful tool for astrophotography.  My primary telescope has a very long focal length.  This means that with the camera that I use, the magnification is very high, and I get a very small slice of the sky.  Any slight error in pointing my telescope could very easily result in missing the intended target.  When photographing very faint objects that can’t be seen with the naked eye, considerable processing can be necessary to bring out the part of the picture that I want.  However, it is often difficult to tell if the target is in the photo frame at all.  It is very difficult to identify stars or constellations in the photo since the field of view is so small.  In addition, since I am using long exposures to try to capture the faint object, the picture is normally filled with hundreds of stars making it difficult to determine if the telescope was pointing in the exact correct direction.

There is a site on the internet called Astrometry.net that is very useful in these cases.  You can upload your picture on the site and the site will analyze the picture and give you the exact RA and Dec coordinates of the center of the photograph.  In addition, it will identify major features in your photograph such as an NGC or Messier object. 

With this tool, you can be sure whether you were pointed correctly.  If you were not, you can try the target again taking more care on the pointing of the telescope.  If it was pointed correctly, you can change your parameters (more exposure time, or a filter) to bring out the target in your picture. 

If you have a motorized mount, you have the challenge of providing power to your mount.  When you are at home you can always run a long extension cord from an outlet to the mount outside, but can be a bit bothersome and also create a tripping hazard in the dark.  Besides, when you take your telescope somewhere dark, it is very possible that you won't have access to an electrical outlet.  You can use your automobile to provide power but that is a poor and troublesome approach.  

One of my best purchases was a rechargeable battery pack to power your equipment.  I first purchased a Celestron Powertank Lithium.  This provided enough power for a night of stargazing and vastly simplified my overall set up.  This particular piece of equipment sells for around $100.  It seemed a bit pricey, but it was certainly worth it.  After about two years, the connection on the battery to the cord that supplies power to the mount started giving me problems.  Apparently the connections inside had become bent and so I would sometimes lose contact and hence lose power to the mount which was of course a very frustrating event.  It also became very difficult to recharge.  Sometimes it just would not recharge even if the connection was good.

I tried to repair the connection but short of totally replacing it, I failed.  I could still get the PowerTank to work with my mount once I was able to get it to recharge, but frustration was building.  I knew that the batteries inside were fine, it was just the connection and perhaps the electronics that take care of the recharging cycles that was problematic.

I started looking for something to replace the PowerTank with, but I was determined to find something less expensive.  Eventually, I found a power pack that had essentially the same storage capacity and power delivery capacity as the PowerTank, but it cost less than a third of the PowerTank.  It is called TalentCell and was originally designed to power audiovisual equipment in outdoors or remote locations.  It has the same connections as the PowerTank, so no modification is necessary.  It is actually smaller than the PowerTank and although I have never used it long enough to totally discharge it, I am confident that it will last at least as long as the PowerTank and probably longer.

So, my recommendation to you is simply to buy the TalentCell in the first place and save yourself a lot of money.  There are other 12v power cells that I am sure would also work and might be even slightly cheaper, but I know this one works and appears to be of high quality.  It can be ordered on Amazon.  Mine is model YB1206000-USB.

If you want to know the field of view for your current setup or even for your camera and its lens, the following website has a good one: 

skyatnightmagazine.com/astronomy-field-view-calculated

I struggled for quite a while to determine a setup so that I could photograph the entire Andromeda Galaxy in a single frame without having it be too small to see the detail.  I had a lot of options; cameras with two different pixel sizes, a telescope with 2032mm focal length, a telescope with 400mm focal length, a 18-55mm camera lens and a 80-210mm camera lens.  The field of view that could be acheived with these various pieces of equipment varied by orders of magnitude.  At the extreme magnification end I could only get about a third of Andromeda in the picture.  At the least magnification end, the Andromeda Galaxy was so small as to be a tiny smudge on the picture.  Using the calculation on the website mentioned above I found conditions that would just fit the entire galaxy and another set up that fit the galaxy comfortably with a nice surrounding starfield.

Use of processing programs to stack pictures

When taking pictures of targets that are very dim such as galaxies or nebulae, it is necessary to “stack” many exposures.  By stacking, the dim features become more apparent and the amount of random noise in the picture is reduced, making the picture sharper.  There are a number of free programs that will help you do the stacking.  The one that I use most often is DeepSkyStacker. 

The use of a program like this requires that the photographer take numerous exposures of the target.  The more exposures, the better, but usually you can get pretty good results with as few as 20 exposures.  All exposures should be at the same length and iso setting.  In general, for dim objects higher iso settings are best.  I usually use a setting of 6400 for three types of objects.  You should use an exposure length of as long as you can to still be able to see details in the picture.  The individual pictures may look quite overexposed (light) but don’t worry about that initially.  As long as you can see individual stars, you will be able to get a decent picture after processing.

Once you have the pictures and load them up into DeepSkyStacker, you will see several other options that will help you get a better picture. There are four that are important:

1 – Dark frames – During your photography session, before you take your equipment in for the night, put the cover on the telescope to block out all light.  Then take 20 or more pictures using the same ISO setting and exposure length as you were using taking the actual pictures.  By having dark frames, the stacking program will be able to identify and remove “hot pixels”.  Any camera utilizing a computer chip will have some pixels that light up even though there is no light at that spot in the actual object being viewed.  It is basically noise and can be effectively removed by the program.  Remember that dark frames should be taken at pretty much the same time as the actual pictures using the same exposure length and ISO setting as during the actual taking of the pictures.

2 – Flat frames – The morning before or after your photography session, take some pictures with the telescope pointing into the early morning sky (not directly at the sun but at an area of uniform brightness in the sky) with a white t-shirt stretched across the end of the telescope.  The camera should be in focus (this can be achieved simply by doing this the morning after a photography session and leaving the telescope focus as it was the previous night.  The camera should be set on the “Av” setting.  The ISO setting can be left the same as the previous night.  The camera will take care of adjusting the exposure time.  (it will be very short).  Take 20 or more exposures.  This will only take a minute or less.  The flat frames will remove a good deal of the vignetting that your pictures have and will also allow dew drops and other imperfections in the picture not related to the actual image to be removed automatically by the software.

3 – Dark Flats – I usually don’t use these so I don’t have any advice on this.  However, they are not required and many experts agree that they are not needed.

4 – Offset/bias files – These frames remove even more noise from your picture and are easy to take.  Also, unlike Darks and Flats, you can use the same set of offsets for different series of pictures (you don’t need a new set for every photography session).  To take a set of offsets, put your camera on your telescope with the cover on the telescope to exclude light.  Use the fastest shutter speed that your camera can handle.  Use the same ISO that you were using on your actual photos.  Then take at least 20 exposures.  These are your bias frames.

After loading up all the pictures, flat frames, dark frames and offset frames, you can start the program processing the data.  The program will ask you what percent of the picture frames that you want to do.  It is good to use less than 100% so that the program will skip the worst pictures.  Even if you are using a guiding program, you will likely have a few pictures that have star trails, a passing airplane or some other problem with them.  I usually set this number at 80%.

After processing you will get a single output picture.  It will likely be very dark (seemingly under-exposed) but stars should appear sharp.  This picture should be downloaded in TIF format.  This TIF picture can then be processed in a photo manipulation such as Photoshop or GIMP(which is free) to get the exposure, color and other characteristics just the way you want it.

A future article will cover the use of GIMP.

Photographing the Sun

On April 8, 2024, there was a total eclipse in parts of Texas.  Since this is a rare occurrence, I planned on taking some pictures of the sun.  Doing this requires a totally different set of skills and procedures than taking pictures of the night sky.  It is essential that a special filter be used whenever viewing the sun, otherwise the viewer can be blinded.  It is best if the filter covers the entire aperture of the telescope rather than just being a filter over the camera.  This protects the telescope from heat that can build up quickly and also is safer since small filters can crack or degrade.

I bought filter material from a US manufacturer and then built the filters for my telescopes myself.

In the weeks before the eclipse, I practiced taking pictures of the sun.  I found out a number of important things that you need to know if you are going to be successful.

1.      Unless you leave your telescope outside all the time, it won’t be possible to align your telescope like you usually do.  Finding the polar north pole is pretty much impossible during the day.  What I did is that I made sure that the telescope was pointed roughly north, and then I connected by planetarium program to the mount and had it slew to the sun.  Then I had to adjust my telescope so that the sun was in its view by releasing the clutches and moving the telescope to the right place.  Note that you can get a pretty good first approximation of where to point by looking at the shadow of the telescope being projected by the sun.  Minimize the size of the shadow and you will be pointing at the sun.

2.      Once the above is done, you will be able to see the sun.  This is sufficient to take pictures over a short period of time.  However, your polar alignment will not be perfect and over the space of several minutes the sun will drift. This is not a problem just for taking pictures of the sun, but if you are taking a series of pictures over an hour or more (like during an eclipse) it is likely that you will have to readjust your mount at some point.

3.      Not all sun filters are the same.  They vary in the amount of light they block.  Don’t take it for granted that the settings you use for your camera using one filter will work for all filters.

4.      Taking pictures of a total eclipse with a single camera/telescope is not easy.  Once the eclipse proceeds to totality (and only then) the filter must be removed and new setting for the camera need to be put in.

5.      You need to have a dark cloak or something to put over your head so that you can see the computer screen!  In the harsh sunlight, you can’t see a computer screen.

I will not try to tell you the settings that will work for your camera.  It depends on the camera, the telescope, and the filter used.  This is why it is critical to try out various settings before the critical event!

I included several of the pictures that I was able to take in the ‘pictures’ section.  Enjoy!