Advice on my results with an Edge8 hd on M27 unguided.

It looks like isn't well collimated and obviously 30s is a bit too long for your mount, or so it seems (oblong stars). So focusing with a not well collimated scope could be the issue with the poor focus. Tis said, you are trying to image at around ~0.4"/px. That is very very adventurous to say the least. You should have binned at the very least with much better hopes to get the focus right. The banding is due to your imaging rig or processing artefact, hard to say without the raw files. I suppose AB&S is a tempting option…

I can relate to a lot of your situation. I have an EdgeHD 9.25 that I bought about 6 months after starting the hobby. I could compare it to a WOGT81. I literally had a love/hate with the Edge for 12 months. Couldn't get star shapes to look right, all images seemed really soft, star elongation etc.

Problem #1: I paired it with a CGX. I know many people have had zero problems with these mount, but mine was/is terrible out of the box. Took experience and comparing it to another higher quality mount to realize it was a quality control issue and no amount of hypertuning met my expectation.

Why it matters: I see star shapes elongated in the same direction which is usually a tracking or guiding issue( orcombo). Can be the mount or problem #2 below.



Problem #2: I messed with the Celestron OAG for a long time and switched to a ZWO large OAG. ZWO has a screw on connection vs. the Celestron thumb screws which have a bit of variability in tension, but it may not have been my problem. I think I also have issues with the .7x reducer and ditching that solved a lot of issues. Native focal length is consistently reliable for me.

The main fix: As part of this experiment, I found that bin2 for the guide camera and especially a large prism AND a large pixel size guide camera (ASI174) worked great. I never am at a loss for finding a guide star. Just be aware that the shape of the guide stars may never be perfectly round due to the offset of the prism. Experience will tell when the guide stars look good enough and just go with it. The final image will be ok. Try to get a guide star that is more towards the center and avoid the extreme corners.



Problem #3: I literally spent a year trying to get my Edge to 'work'. I was about to give up and go with the reliable refractor full time. I had dumped enough money into adapters, Hotech laser collimator etc. that I tried one last thing. I sent it back to Celestron for cleaning and alignment. It came back in perfect condition. Bob's Knobs may have been an issue, but what I found made more of a difference was… the mirror lock knobs! If I tighten them too much, I get coma. The factory had it in this semi tight state and when I reproduced their tightness, the star shapes were good. I also heard less of a creaking sound when moving the focus knob. Even when the locks were completely loose/off, the mirror was binding on the shaft and audibly popping into alignment. I think they regreased the internal shaft.

So after all that - short answer: Large prism OAG, large pixel size guide camera(5.86) bin2, double check guiding because if it is constantly correcting one extreme to the other due to your guide star issues, balance, etc… it will make the whole image soft. Seeing makes long focal length scopes softer anyways, but it shouldn't be super soft. Oh and set it and forget it with mirror locks and then using a moonlite focuser for fine tuning focus was a major game changer for me.

Hi Sam,
there is more potential in a C8 - a view on images on astrobin will convince you. I started my astrophotography journey last year using an old C8 on a super polaris mount from the 90s. The initial results were poor - DSLR, no guiding, stock focal reducer with horrible aberrations, etc. Slowly and carefully I have added the correct peripherals and finally I just got a first image of M27 with just 1 hour exposure from bortle 8-9 for which I am pleased with (and I still have a long way to improve - I still need to improve my collimation and tilt - along with processing skills!).

In my opinion you need to fix your guiding as a priority.

There are several ways: Either get a good guide scope (60mm aperture), or try to get the OAG to work. I struggled for ages with my old celestron OAG, until I bit the bullet and got a Starizona corrector for my C8 (not sure if you need one for EDGE - but maybe get the focal reducer), and a ZWO OAG. This way, I have nice tight stars even at the OAG and I ensure the correct focal distance for my camera + guiding eyepiece to be at the same focus.  (side note: my mount has significant DEC backlash and calibration was close to impossible - I now ensure that (i) the calibration steps movements are large, (ii) I assume DEC orthogonal to RA, and (iii) if PHD2 callibrates by moving north first, I make sure the last movement in DEC before calibration was North).
If you are shooting from the city you need a good light pollution filter.




https://www.astrobin.com/1ibcf3/

I always felt like an 8" SCT was stuck between two worlds. Kind of needs more aperture and focal length for planetary but way too slow for deep space objects. Yes a reducer can help but if your plan is to focus on taking pretty pictures of deep space objects then a fast Newtonian is the way to go (8" or larger, F5 or faster). For those who like to image galaxies, I see large RC/CDK (minimum 10") style scopes being used. There isn't really a "wrong" scope per se but each format has their niche where they really shine.