How much to cool...

[gaz81]

So hopefully this is a simple question. 

I know have a 1600MM pro.. so it can cool. 

What temp should I aim for? -10... -15... etc. 

First night with it I cooled to -10 (actual temp I think)  

I managed some Ha of Heart Nebula for my first go... with a big bright moon!

Still a lot to learn, just used unity gain 139 and 300 second subs, only had 1 hour total time in the end  

Was a whole fresh install of software so was fight that for a while 🙂

 

[teoria_del_big_bang]

I have always used -20 C as it never struggles to get to that point even in warmer weather (not that is a problem for us up North 🙂 ) and the cooler the better (to a point).

I also have tended to stick to unity gain with an offset of 40 but in all honesty not experimented much with these figures as they just seemed to have worked but with a bot of science behind it I think some gains work better in some circumstances but not experienced enough to say what works and what doesn't.

Steve

Edited January 26, 2021 by teoria_del_big_bang

[Spaced Out]

Like Steve I also use -20, works well and I've never had any problems cooling in the warmer spring/autumn weather.

[gaz81]

Yeah was pretty cold up here on Sunday night! 

Might try for cooler then next time. 
 

I use APT and didn’t touch the offset.. so not sure what the gain was. 

[rickwayne]

Couple  of points to consider.

Cooling, like  other noise reduction techniques, is a game of diminishing returns. I wind up recommending Robin Glover's talk on CMOS exposure a lot, he shows some cooling/noise curves that should make you take notice: https://www.youtube.com/watch?v=3RH93UvP358

If you're in the field, the cooler is pulling watts out of your battery, and that curve isn't linear either.

As you've probably already figured out, doing all your work with the minimum number of sets of parameters minimizes the number of calibration frames you need to shoot. And that's combinatoric too. I shoot at the same temp, winter and summer, the same offset, and one of two gain settings depending on whether I'm shooting narrowband or LRGB. That's it.

[Skipper Billy]

My camera (ATIK 16200) can easily cool to 50 degrees under ambient.

I take a full set of calibration files just before the season starts - late August. A full set of darks, flats and bias for every filter and every exposure I might use and binned 1x1 and 2x2 can take 3 days and nights to gather. I use these throughout the season.

So I picked a temperature that the camera can reach in August and that is unlikely to be warmer than the ambient temperature too often and doesn't stress the camera too much whilst giving the optimum noise reduction (its a noisy camera).

-20 Celsius is where I got to and it has worked very well for me.

 

 

 

[Skipper Billy]

1 hour ago, rickwayne said:

Cooling, like  other noise reduction techniques, is a game of diminishing returns. I wind up recommending Robin Glover's talk on CMOS exposure a lot, he shows some cooling/noise curves that should make you take notice: https://www.youtube.com/watch?v=3RH93UvP358

That's one of the most enlightening things I have seen on YT. I seem to be doing the right things by accident - Bortle 2 skies, noisy Kodak chip etc !!

[gaz81]

Seems I wasn’t using any offset then?

[gaz81]

Ahhh... thanks to Cuiv I looked in the ASCOM driver settings to see what I should have set it to. 

[gaz81]

3 hours ago, rickwayne said:

Couple  of points to consider.

Cooling, like  other noise reduction techniques, is a game of diminishing returns. I wind up recommending Robin Glover's talk on CMOS exposure a lot, he shows some cooling/noise curves that should make you take notice: https://www.youtube.com/watch?v=3RH93UvP358

If you're in the field, the cooler is pulling watts out of your battery, and that curve isn't linear either.

As you've probably already figured out, doing all your work with the minimum number of sets of parameters minimizes the number of calibration frames you need to shoot. And that's combinatoric too. I shoot at the same temp, winter and summer, the same offset, and one of two gain settings depending on whether I'm shooting narrowband or LRGB. That's it.

That was a great video! Might have to watch some bits again though! 

[rnobleeddy]

+1 for -20

[JamesF]

4 hours ago, rickwayne said:

Cooling, like  other noise reduction techniques, is a game of diminishing returns. I wind up recommending Robin Glover's talk on CMOS exposure a lot, he shows some cooling/noise curves that should make you take notice: https://www.youtube.com/watch?v=3RH93UvP358

I was thinking about this earlier.  I assume his points about cooling apply just as much to CCDs as to CMOS sensors.  In which case it should presumably be possible to capture darks at a range of different temperatures and find the point at which cooling your CCD makes no significant difference at the exposure time you're interested in using.

James

[rickwayne]

Yeah, I rewatch that from time to time just to glean some more info and ensure that I haven't strayed. You see a lot of people pontificating on fora who seem very sure of themselves, but Dr. Glover just brings it, doesn't he? Harder to argue with the data right there in front of you. Of course, that certainly doesn't mean he's always right. But it's considerably more convincing than "I do it this way and my pictures are awesome so you should too". One of the reasons I treasure Vlaiv's comments on this forum -- he always sets out quantitative reasoning behind his assertions.

Edited January 28, 2021 by rickwayne

[Davey-T]

On 26/01/2021 at 23:39, JamesF said:

I was thinking about this earlier.  I assume his points about cooling apply just as much to CCDs as to CMOS sensors.  In which case it should presumably be possible to capture darks at a range of different temperatures and find the point at which cooling your CCD makes no significant difference at the exposure time you're interested in using.

James

Tried suggesting to mods that they ask Dr Glover to do this talk on Stargazine as they were asking for suggestions but nowt came of it perhaps someone else could mention it.

Dave

[The Lazy Astronomer]

Another +1 for Robin Glover's advice. As with seemingly everything in astrophotography, it seems that extreme cooling is very much a case of diminishing returns.