Finally got a clear night during the week to test my new set up. It wasn't the best night even though it was relatively cloud free, but everything seemed to work out pretty well.
Polar alignment was good this time, guiding was going very well (.7 to .8 for this set of subs) which may be due to this scope weighing 3 or 4 kilos less than my other one, even with the camera and guide scope.
Anyway I took a quick set of 20 x 120s @ ISO800 with my Canon 60D. The scope is a Saxon ED120 with the Saxon/Skywatcher/Orion 0.85x reducer. No dithering or anything, I was just testing waiting for my actual target (M20 later on in the night).
A couple of other changes I made were to split the RGB channels out in PI and then linear fit them to green before recombining and continuing the usual processing. I tried a few combos, but fitting to green seemed to give the lowest noise and least saturated / blown out stars.
Couple of questions, are these star colors getting close to correct? and is the overall color balance good? The filter was an optolong l-pro and the canon is modified now, but it's more red than I expected.
Also I've added the aberration inspector mosaic from PI (from a single sub), I think that is sensor tilt? Bottom left and top right panels sho the elongation of stars I expected around the edge of the field, but top left and bottom right don't.
Elliot, that looks a pretty nice picture of 3372, very pleasing to the eye. Maybe a little red for some but I like the contrast and the strong colours you've managed to produce here. I think your star colours look good and the modded dslrs always tend to lean on the red side but hey, you modified it to get more Ha response so it's doing the job. You'll get the hang of better colour balancing tricks as you gain experience. Regarding the coma in those corners, it is a bit odd it only appears in those diagonally opposite ones and not the other side. Is the reducer a field flattener too?
I use a field flattener on my Esprit 100 and it works well on all corners and I now have a coma corrector for my 200mm f 8 Newtonian which has helped heaps with coma at the edges. In your case it could be a tilt problem. Some of my camera lenses, if I use them for widefield shots, exhibit a similar result as what you've shown, especially at low f numbers but I have the ability to stop down a few to eliminate some of those issues. Let's hope someone else can shed a light on resolving your lens aberration problems.
Very nice image of Eta. The red's are strong but it is a Hydrogen region, there is a lot of H alpha signal to capture. Maybe dont boost or dial back the saturation a tiny bit on the reds, since there is so much red signal for this object? It's really down to personal taste though.
thanks, it is a little too red for me too. It's from the combination of the L channel back with the RGB data I think, I can adjust that a little to lighten or darken it and adjust the saturation. I left it close to default this time.
I've been trying out some different ways of processing in PI, but this image came out suprisingly well without all that many steps, I was quite pleased. I may have got lucky with setting up the scope first time around.
There's a few issues to solve, but I'm planning on getting some more data with this setup over the next few clear nights (however long that takes..)
Firstly I think you have a really good result. You should be be very happy with that. Secondly it looks like you might have a couple of gremlins in your setup. There's a program called CCD Inspector which is really helpful with checking for things such as tilt. There's a trial version which you can download and have a play with.
