ZWO 1600MM-Cool & Dithering

[groberts]

I just read another post on SGL which has got me confused.  Shortly after  I acquired my ZWO 1600MM-Cool at the end of 2017, I was told that dithering would not work with this or any other CMOS based camera (not sure why & probably wouldn't have understood it anyhow) but I now see others talking about just this.

1. Can you dither with CMOS and especially the ZWO 1600MM-Cool?
2. What setting works best with the 1600MM-Cool?
3. Does it make much difference to the final image with the said camera + if so in what way?

Thanks, Graham

 

Edited April 6, 2020 by groberts

[SyedT]

Dithering for me was a game-changer with my 1600MM-Cool. It was prone to getting significant fixed pattern noise, and dithering completely eliminates this once you've done the stacking. As a rule of thumb, I would dither every 5% of frames e.g. if I was taking 100 subs I would dither every 5 subs. Again, this is a general guide I found online, and I ended up experimenting to minimise dithering whilst still getting a benefit from it (as it does add time to imaging). I've long since sold my 1600MM-Cool and moved over to an Atik 490EX, and I found that dithering less often works well with the Atik.

[Anthonyexmouth]

Is there ever a time dithering can be a problem? granted, only had a few cameras but back when I started with a Canon I have always dithered, APT is set to dither every frame and I dont even think about it. Currently using a 294mc pro. 

You lose a few edge pixels when stacking but seems to make for a cleaner image in most situations.

[groberts]

Thanks guys.

I now recall that is was binning and not dithering that apparently does not work with CMOS sensors - don't understand why?  Notwithstanding, I'm pleased to hear that dithering does work and, furthermore, is worthwhile.  Will give it a go.

Graham   

[SamAndrew]

Hardwear binning on CCD cameras is a way of overcoming the high read noise. CMOS sensors have lower read noise so binning isn't necessary.

[Astrobug]

22 hours ago, Anthonyexmouth said:

Is there ever a time dithering can be a problem? granted, only had a few cameras but back when I started with a Canon I have always dithered, APT is set to dither every frame and I dont even think about it. Currently using a 294mc pro. 

You lose a few edge pixels when stacking but seems to make for a cleaner image in most situations.

Random dithering works fine but don't try spiral dithering. You will see strange things on your stacked image.