CMOS confusion

[+Stu]

Hi. I had a go with the 269C last night and I have teething problems.

Using my 80/560 refractor I did 120s exposures at 282 gain which is unity gain and 15 offset. 

1) It's not really captured much, DSS can only detect 6 stars at the lowest registering threshold.

2) The image came out grey with only 1 channel. Having a look through APT, should I have Colour FITS preview ticked in CCD settings? When I tick monochrome in DSS and try to register it comes up with incorrect amount of channels. Will fixing this also solve the extremely dark subs? 

[+Stu]

17 minutes ago, Stu said:

Colour FITS preview

Ok, so that only affects the preview. Should've twigged that. 

[Bob Dobber]

You need to have the box ticked in the FITS tab in DSS settings since you're using a colour camera, right? I presume it is RGGB bayer matrix?

[+Stu]

I was trying that and it wasn't having any of it, seems to work now 👍

With the lack of stars, is that just small aperture/not very dark sky? I was aiming at M101, a bit fainter than stuff if usually try. 

[Clive]

1 hour ago, Stu said:

 

1) It's not really captured much, DSS can only detect 6 stars at the lowest registering threshold.

Your setup isn't so dissimilar to mine (400mm FL f5.6 with 3.7um pixels). I imaged M101 at 180s and DSS found 100s of stars when stacking. So I guess it's a setup problem rather than an equipment one.  Have you looked at the stacked image?  DSS is very picky when it comes to detecting stars, any bloated (out of focus) or misshaped (poor guiding) stars will be rejected.

 

I've still not got around to processing my stacked M101 image yet and unfortunately it was captured a few weeks ago as a supernova was discovered in M101 yesterday!

[+Stu]

I had to crank the gamma in DSS right over to the left to see maybe 10 or 15 stars on the subs. I was using a flattener at F7 using the stock nosepiece which I measured be 32mm, plus 5.5mm extension to give me 55mm with the camera having 17.5mm back focus. 

 

The image I managed to stack had some date there, but also had to crank gamma right up in Affinity to see anything. It was just blackness to start. 

Edited May 20, 2023 by Stu

[+Stu]

[+Stu]

My only thoughts were try using the flattener/reducer at F5.6, or using all M42 fittings between the camera and the flattener. I added a focusing EP holder to my guidecam but it just wouldn't focus, couldn't see any stars and just got static in PHD2. Removed the EP holder (after spending way too long messing around with it) and no problems. I'm also using a 2" 50mm extension tube in the scopos focuser, could removing that be a benefit?

[+Stu]

I think it's something in APT. If I take a quick exposure now, I get near enough a black screen. If I use Sharpcap or Altair Capture I get a white screen which I'd expect 🤔

[+Stu]

I believe I may be sorted. Many thanks @Bottletopburly