Nine months ago I decided to go into astrophotography as a hobby. Thanks to forums like this and others I have learned so very, very much. I’m still learning, but I feel compelled to ‘give back ‘ to the community, in particular beginners so that they might save countless hours of frustration and confusion as they get into this hobby. It incredibly rewarding but at the same time can be very frustrating.
The opinions I express are my own; I don’t represent any company or entity. Perhaps there are other opinions and I’m fine with that. These are just mine. The following sort of bares my soul with stupid and embarrassing mistakes but if it helps some folks new to the hobby, its worth it to me.
I wanted to photograph deep space objects but also be able to photograph the planets. Perhaps against the advice of some, and after considerable research, I jumped right in buying a Celestron 9.25 inch CST with a CGEM ii mount. I almost made the mistake ( for me ) of buying an alt/az mount with idea of getting a wedge. The more I read about it, the more I decided to get an equatorial mount which is preferred for deep space photography. Fortunately, my original order which was alt/az was back ordered and I was able to change my order to a CGEM II mount which is what I have.
Suggestion 1- Get an equatorial mount if you want to do deep space photography. You need it.
All excited, I received my scope and mount and decided to set it up on my pool deck ( limited sky view ) and give it a test drive. My first mistake was to not change the time and location in the hand controller and as a result the scope almost skewed itself into the tripod.
Suggestion 2 – Out of the box, don’t forget to put in your longitude and latitude and time.
Anxious to use my new scope, on the first clear night I set up at a location with a clear sky view and tried my first alignment for my “go to “ scope. Celestron has a couple of built in options where you skew to a star, center it in the eyepiece, and then go to the next star. I seem to recall it suggests four stars ( I haven’t used this option in a long time ).
I recall from that first night and many afterwards that I screwed around for hours trying to do this. Finding the star in the eyepiece ( must less centering it ) was very difficult using the finder scope that came with the telescope. I also realized that I always seemed to be physically contorted looking through the eyepiece ( with the diagonal ) so physically it was quite challenging.
Suggestion 3 – Run don’t walk to your nearest supplier and by a Tel Rad finder scope. You can’t live without it!
Once I had the Tel Rad scope, I was able to find the stars, center them, and at least have a shot at a decent goto skew. However, then came polar alignment.
The handset includes a polar alignment routine that in a similar fashion asks you to slew to a particular star and then center it using the mechanical altitude and azimuth knob adjustments on the mount. Ok, I can do that! But guess what, after you do the polar alignment you have to start all over with the goto alignment because you have now mechanically changed your mount.... Back to square one.
There is another way to do polar alignment by buying a polar alignment scope that fits into the mount. I bought one, used it, and eventually decided it was not a good solution. IMO you can not get a good polar alignment for astrophotography with this method. Also, depending on your latitude, its difficult to look through the scope without a diagonal. I wasted $100 buying one –( let me know if you would like to but it from me)!
Suggestion 4 - If you need precise and quick polar alignment, buy a PoleMaster. IMO it is fantastic. Accurate polar alignment within 5 minutes and before you can visually even see Polaris ( but the camera can. )
Suggestion 5 - I learned the hard way that PoleMaster didn’t seem to work on my Windows 10 laptop unless I run SharpCap in the background with the SharpCap HD Web camera option activated. One night was wasted until I found that little piece of information. Perhaps there are other solutions.
So now I could do a quick polar alignment, but the GOTO alignment was still taking me way too long, even with the Tel Rad finder scope. Also, if your mount shuts down for any reason ( battery for instance), or you have to turn it off in an emergency because it looks like it is slewing to Australia ( go ahead and laugh, it will happen to you too), you have to start the goto alignment process all over again. It gets old after awhile.
Suggestion 6 - Buy a Star Sense Camera. Yes, its expensive but it is soooo good. My go to alignments went from perhaps 30 minutes at best to about 5 minutes. Its awesome. Buy one. You will never regret it. It is so cool!
Suggestion 6a - Make sure you use a calibration star the first time you use it to align it with your scope. If your goto objects ever aren’t accurate, first thing to do is to recalibrate that alignment. ( Learned that the hard way one night. )
Suggestion 7 – Make sure when you use the Star Sense Camera you take the lens cap off. Ok, I know what you are thinking. When someone admitted on one of the forums that it happened to them, I said to myself what a dummy. Well, I did it too once but realized the problem quickly.
Focusing is a big deal in Astrophotography. Many software programs allow you to access a motorized focuser from within their interface which is very convenient. This is not a must have, but a really, really nice to have.
Suggestion 8 – You’ve spent this much money already, why not go for broke and buy a focus motor.
If you do, make sure you check the collar screws from time to time. I was at the darkest sky east of the Mississippi at Kathadin Mountain two weeks ago when my screws decided to loosen. It took me a half an hour and process of elimination of precious night sky to figure out what was going on. The deceiving part was that I could hear the focus motor rotating, but the star would never come into focus and I had just changed over from wide field to prime focus...
You need a camera to do astrophotography. There a many choices, I decided on a Canon 6M Mark ii which is a mirrorless DSLR. After taking many photos over the first six months, I decided to have the camera modified to remove the internal filter that blocks red. It was difficult for me to send a perfectly good camera away and have someone modify it, which voids the warranty, but my photos are so much better now when capturing Ha dominant nebula.
Suggestion 9 – Have your DSLR modified for Astrophotography.
Along those lines, I highly suggest buying an Ha clip in filter for your camera. Between that and the modified DLSR, the Ha comes through in spades.
Suggestion 9a – Buy a clip in Ha filter and learn how to combine and process HaRGB photos.
I use Backyard EOS to manage my picture taking chores. It is one of the best value pieces of software IMO around. There are many packages around, another is N.I.N.A which is free and fantastic, but a bit more complicated to use if you are just getting started.
Suggestion 10 – Start with Backyard EOS, Premium addition.
If you decide to use Backyard EOS to take photos in the planetary mode using 5x magnification, you might have to turn the power saver features off in your camera. I did because the 5x mode kept dropping out when I was taking planetary photos. ( another aborted session until I solved that problem!)
Its not long before taking photos that you realize you need to add a guide camera to your telescope for any extended exposure times... perhaps more than 60 secs or so. A guide camera is essential. I bought a ZWO ASI 174mini and the Celestron OAG ( off axis guider ).
Suggestion 11 – Buy a guide camera and off axis guider; you need one for DSOs ( Deep Space Objects ) Before you buy Celestron’s, see comment below using Field Reducers. PHD2 is the overwhelming guiding software and its free. Make sure your guide camera has a ST4 port.
It is crucial that the sensor from the guide camera to the visual back and the sensor of your DSLR to the visual back is exactly the same distance, else the guide stars will be out of focus. Take the time to set this up at home using a pair of calipers; it will save you lots of frustration.
If you have ASCOM installed ( see below ) your guide commands can come through the PHD2 software to your mount. If you don’t, you need to connect your guide camera directly to the mount using a ST4 cable. The downside to that is that you must recalibrate your guide camera when you slew to a different location. Using ASCOM, PHD2 adjusts itself because it know where you went.
I like to use my 9.25 SCT with a field reducer sometimes to get a bit more field of view so I bought the Celestron f/6.3 Field Reducer / Corrector. I found out the hard way that it is impossible to get the proper back focus ( distance ) from the surface of the reducer to the DSLR camera sensor using the Celestron OAG guider. One would think this would all work together nicely; it doesn’t. Celestron told me I had to have a special spacer made and gave me the name of the machine shop to make it. I finally broke down and ordered it but haven’t received it yet. In the meanwhile, I was able to get close using some of the parts that came with the OAG but I hope for improvement when the focal plane is in the right place.
Suggestion 12 – If you plan to use a field reducer, consider buying a different OAG than Celestron’s; one that is thinner to allow the reduced back focus spacing. ( Needs to be 105 MM ).
Plate Solving is a wonderful thing. It uses your camera to take a photo and compare where you are to where you should be ( Lat,
Long) and centers your picture for you. This is particularly useful if you take pictures of the same object on different nights. It minimizes how much you need to crop when you final pictures ( subs ) are combined.
Suggestion 13 – Use ASTAP plate solver if you use Backyard EOS because they are compatible.
Speaking of software, after using several free programs that compile and post process your RAW images, I have become a fan of AstroPixel Processor and Photoshop for my DSO photography. I’m sure others are great also, these however are my current choices.
Suggestion 14 – Try as many different software packages as you can and choose the one to your liking. Many give free trial use so you can evaluate them. Deep Sky Stacker, AutoStakker, Gimp, Registax, just to name a few.
Its not long before you get tired of using the hand controller to control your scope. I use the free software from Celestron called CPWI. You must install the ASCOM platform before installing CPWI. Just google ASCOM and it will take you to their website. ASCOM is free.
One neat feature of CPWI is that you can connect a game controller to your computer and use it to both slew and focus the telescope. Just be careful you don't accidently drop it off your work table because if it lands on the joy sticks.... well, you know! ( Its happened to me twice )
My most recent quandary has been creating a Periodic Error Correction ( PEC ) curve. CPWI did this for me once but left me hanging when I tried to replace the curve with a better one. I think this is still a bug in CPWI.
I downloaded the PEC tool from Celestron and had a few false starts trying to use it. You must load and run it using emulation mode ( Windows 7, I recall ). Also, you can’t use CPWI or ASCOM because PEC won’t connect to the mount ( its really old software ).
Suggestion 15 - To use PEC on Windows 10, connect the hand controller to the computer and connect the guide camera directly to the mount using a ST4 cable. PEC will then connect to the mount and become usable.
PEC allows you to run multiple PEC correction curves and average them. I’m just now fooling around with PEC to see if it improves my guiding.
So there you have it, my learning curve of 9 months in a few paragraphs. I really hopes this helps someone avoid some of the many pitfalls and frustrations this hobby has to offer.
It would be great if others added their most memorable and embarrassing screwups, fixes, or advice on issues that the rest of us have not yet experienced....\
Clear Skies –