Celestron CPC 800 Astrophotography and EAA Review

By: Vlad Fedosov

Intro:

This is not my first encounter with the CPC line of scopes(see CPC 9.25” review). This is, however, my first time using one for the purpose of astrophotography(really its Electronically Assisted Astronomy(EAA)) so I was excited to see how I would like the 8” version of the CPC in this application. My CPC 800 was outfitted with the optional Celestron HP Pro Wedge, Star Seance, and the Celestron Wifi dongle. The CPC line of Celestron telescopes are made to compete directly with Meade’s LX-200 line of fork mounted SCT’s. These are a no-compromise heavily duel arm mounted SCT’s that have GPS built in as well as GOTO. The CPC  800 weight in at a total of 61lb dry without any accessories. Let’s take a look at how this setup performs under the night sky!

Testing:

I tested this setup form my mag 4 light polluted back yard, right where I like to do EAA! I will start off by saying that this scope setup sure is pleasing to look at! It’s just a really beefy looking setup that certainly looks like it’s up to the task of doing some serious astrophotography. With the scope setup during the evening and roughly polar aligned I was ready for nightfall and to get this thing aligned with the Starsense.  Touching on the aspect of setup with this rig: Setup is easy in the sense that unlike a German Equatorial Mount(GEM) mount there are less individual pieces to put together. What is not as great is the fact that the two main components of the scope are quite heavy especially considering that this is only 8″ of aperture! The tripod/wedge combo is particularly heavy. You could theoretically carry out the tripod and wedge separately by unbolting them every time but that’s a bit of a chore. The wedge does have a nice grab handle on it that does make carrying it a bit easier. The scope portion is also no lightweight at 42lb. You certainly need to be a healthy individual to lift this rig onto the wedge.

Once nightfall was near I decided to see what the Starsense was all about. I positioned the OTA in its home position as required and told the scope to auto align. I was curious to see how well this would work as about 50% of my sky is blocked from my backyard. About 5 minutes later I was greeted with a message that the alignment failed… Not too great as the Meade Lightswitch I reviewed earlier was able to auto align from the exact same spot in my backyard. Not too much of a setback as there is a manual alignment option to where you decide what 3 spots on the sky you want to point the scope at so that the Starsence can take a picture and do the alignment. With this method I was aligned and ready to go in about 3 minutes. Not bad, but honestly not much easier than the alignment that all modern Celestron mounts/scopes use to where you just center 3 bright objects in the scope and the alignment is complete. I’m sure the Starsence would do great in a sky that was near 100% open.

Now that all the technical details were out of the way I proceeded to hook up my ASI 294MC Pro to try out this setup for some EAA. The images were all taken at f/6.3 with the use of a Celestron reducer. Since it was still galaxy season I decided to point the scope at m66 which is a part of the Leo triplet and a fairly easy object for EAA. Pointing accuracy with the CPC was obviously up to the task of placing an object near the center of the FOV of the 294MC Pro. I used 5-second exposures to form the image in Sharpcap(this is typical for what I use even on my primary EAA rig that can easily do multi-minute exposures). As you can see the CPC 800 managed to produce a nice image with stars that are still nice an round. I will admit that I even had a very rough polar alignment. The overall number of frames dropped due to FMA error was much higher than with my permanent EAA setup(c8HD on g11 mount). This seems to indicate to me that the stability of the mount or more likely the tracking had quite a bit more jitters. The difference was really quite a bit compared to what I’m used to with my g11 and C8HD. The setup is still capable of nice results.

I’m still going through the Herschel 400 list with EAA and I decided to do the constellation of Sextan even though it was low to the horizon already and this particular night did have a bit of haze. Well, all I can say is that the CPC did a very nice job finding all the galaxies in the constellation(only objects on the list in this one) very nicely. The images were not super impressive since I was looking through a lot of muck. It did, however, give me a good sense for how this setup will perform for astrophotography(or EAA). I think it’s not a bad setup at all if you are ok with confining yourself to one OTA!

Conclusion:

The overall conclusion to me as to whether I would recommend this setup to someone is somewhat of a mixed bag. If you already own a CPC scope and want to get into astrophotography with the emphasis on planetary imaging, then yes you already have a nice scope for that. All you need is a 2-3x barlow and a cam such as the ASI 224MC. No wedge needed. If you really like your CPC and do not want/cannot sell it to get a GEM mount/different OTA and want to try out wider field DSO astrophotography you can get the Celestron wedge like my rig had and a Hyperstar to do imaging at f/2. Very capable setup. You can obviously do mid focal length work on planetary nebulas and small galaxies in the configuration that I was running as well. In a way, this is a very versatile setup! If you are buying a fresh setup not owning a CPC than I really would recommend a GEM mount and OTA. You will have a mount that works better for astrophotography and the ability to use any OTA that is most suitable for your object of interest. The other huge downside to the CPC astrophotography setup is the sheer weight of the two larger components of the rig. They are just not much fun to setup, but conversely a lot of fun to use!