Sorry that it has taken me so long to give you this update on my experience with my new ASI294MC Pro camera that I bought after all your help and advice.
I have an older 11" Nexstar GPS, fl. 2700mm, mounted on an equatorial wedge, that I wanted to use for DSO photography. I knew that I would probably have some issues due to the focal length and image scale, so I also bought a Starlight Express AO unit with OAG. I already had an SX Lodestar guide camera.
To run this lot I have AstroArt-7 plus PHD2 guiding software.
To run that lot I also bought a new MSI laptop with backlit keyboard!
Then I packed all this lot up and went off to La Palma, Canaries to use it at 8000ft under some nice dark skies. So I wasn't expecting to get absolutely brilliant results first time! Unfortunately it was too windy to image on two nights, but the third night was much better.
So, I did set up the camera plus SX-AO unit and took a few test images of the Lagoon and Triffid nebulae but due to misreading the histogram, I seriously over-exposed the images. I did not see the spike hard over to the right at 65,535. I also forgot to turn on the AO unit power supply so no auto-guiding!
I am now home again in England and starting to get everything set up in my small observatory. On 22 Oct we had a few hours of clear skies for me to start testing my setup. Unfortunately I could not get the auto-guiding software to work with my SX-AO properly, so I decided to use the last hour or so of clear sky to do a bit of unguided imaging on M27, compressed image attached. Obviously the image is not that great because I could not expose for long enough due to lack of guiding causing some massive star trails.
The image is the result from the best 10, 45 sec subs (least trailing), stacked in AstroArt-7, and then post processed in PhotoShop. Due to the star trailing issues I didn't bother to calibrate the image, so no flats or darks.
Considering all the issues and lack of photons, I was surprised it came out as well as it did!
The exposure settings I used were: 45 seconds subs, ASCOM settings Gain= 130 gain, Offset=30 and USB Limit =80 as previously advised.
However, I have quite a few questions that I would appreciate some feedback on:
1. ASCOM camera settings Set Point © -5. Is this -5C below ambient or -5C actual chip temperature?
2. The histogram of an individual raw sub showed a max ADU of 6137 so I thought that I would increase the gain setting so I doubled it (as doubling the exposure time would have resulted in bad star trails) to Gain=240 but it did not seem to do much to the max. histogram reading. It certainly did not double it. Why not?
3. Examining the raw image subs, the bloated star to the right of M27 appears to have a max ADU of 17,736 in AA-7. This is curious as the max on the histogram is 6137. I need to check this out as maybe doubling the gain did double the max ADUs but just didn't get reported on the histo.
4. The bloated star has a pixel dimension of 70h x 60v pixels. I calculated the pixel image scale to be 0.34 arcsecs/pixel on my setup. This means that the star image is c. 20 arcsecs dia. Can anyone please suggest why this should be so, the atmosphere was reasonably stable and transparent (for the UK at 21 feet elevation and downwind of London!).
5. Can anyone please tell me how I can process 32 bits FITS files in Photoshop CS2? I used to do this by using FITS Liberator I believe, but when I installed it and imported the final stacked and debayered image in FITS format, I could not remember how to get FITS Liberator to save it in a Photoshop compatible colour output file!
6. I noticed a colour cast over the centre of the image but I hope that when I calibrate the images, i.e. flats and darks, this will disappear, as per a previous posting in this thread.
Any answers to the above questions would be greatly appreciated.
Edited by iandh2010, 24 October 2019 - 10:01 AM.