#1  
Old 11-05-2021, 07:43 PM
RugbyRene (Rene)
Registered User

RugbyRene is offline
 
Join Date: May 2015
Location: Sydney
Posts: 259
Best cooling temp for the ASI2600MC

I realise this is a very subjective question but I'll ask it anyway.

I have a brand-new ASI2600MC (picked up today). Before I use it in anger I was wondering what is the optimal temp to cool the sensor to? With my old 294 I would cool to -5 Celsius but with this new camera I wanted to push it a little further but not over-tax the cooler.

So I'm open to what other people have used.

Rene
Reply With Quote
  #2  
Old 11-05-2021, 10:10 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 2,975
I used to use -15 with my ASI294 but I use -10 with the 2600MC, I could not see any significant change by going colder so I went with that as I was sure it could maintain it all year round. It has a bigger heatsink than the 294 as well, so temperature for temperature it does easier with lower cooling power.
Reply With Quote
  #3  
Old 11-05-2021, 10:34 PM
Startrek (Martin)
Registered User

Startrek is offline
 
Join Date: Dec 2017
Location: Sydney
Posts: 3,503
Have a look at the Dark current graph provided by ZWO
At -20C dark current is extremely low on this camera so -15C would be an acceptable level , although it all depends on the ambient outside temperature of your imaging location summer and winter.
My 2600MC cooling set up ......
Sydney summer I can get down to -12C on most nights but I had some really warm nights where it stopped at -10C or -11C
Sydney winter I run at -15C no problem
South coast NSW summer I get down to -12C no problem
South coast NSW winter I run at -15C
I suspect in colder climates around the country -20C would be achievable but not absolutely necessary
Reply With Quote
  #4  
Old 11-05-2021, 10:58 PM
AdamJL
Registered User

AdamJL is offline
 
Join Date: Sep 2010
Posts: 522
Whatever you’re happy building a dark library for
I usually pick -10 but I might try -15 this weekend if the weather holds
Reply With Quote
  #5  
Old 12-05-2021, 09:45 AM
RugbyRene (Rene)
Registered User

RugbyRene is offline
 
Join Date: May 2015
Location: Sydney
Posts: 259
I've settled on -10 as it's a temp I can use all year. Time to start building my darks library.

Thanks all for your input.

Rene
Reply With Quote
  #6  
Old 16-05-2021, 09:32 AM
DiscoDuck's Avatar
DiscoDuck (Paul)
Raider Nation

DiscoDuck is offline
 
Join Date: Apr 2014
Location: Adelaide
Posts: 567
I'd suggest you can be quantitative about this if you like.

Assuming you've chosen an exposure time so that you are sky limited with respect to read noise, then it would make sense to ensure that the noise from the dark current is of the same order (or less!) as the (now negligible) read noise.

So if your camera's read noise is R and you are exposing for T seconds, you need to cool so that your dark current is no more than R^2 / T.

Typically for CMOS cameras at reasonable gain, R is say 1.5 ish. So you might try to get the dark current down to say less than 2/T.

For the ZWO2600, the dark current is remarkably low and is about 0.002 at 0 degrees apparently. So even at 0 degrees I'd suggest you could do 1000 second exposures.

For the ZWO1600, things are much worse, and say you want to do 10 minute narrowband shots (T=600), so you need dark current no more than about 0.003. This is not achievable even at -20 (may be at lower temps, but the curve I saw didn't go down to -30, which is apparently the lowest it can be set). At -20 degrees, you get dark current of 0.0062, and so you can do no more than about 300 second exposures before the dark current noise climbs above the read noise. That's not to say you CANNOT do longer exposures, just that your noise from dark current will start to be the thing you worry about rather than your read noise.
Reply With Quote
  #7  
Old 16-05-2021, 02:43 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 2,975
I didn't go quite that far down the rabbit hole, but considered similar. Essentially my dark current at -10 degrees is 1e or less at any exposure time I am likely to ever use so I considered that good enough for all practical purposes. Really my master darks are more read noise characterisation than dark current. Maybe I should just calibrate with a master bias instead.

The only difference there of course is hot pixels, but with a good number of subs APP will probably reject those anyway.

Last edited by The_bluester; 16-05-2021 at 03:20 PM.
Reply With Quote
  #8  
Old 18-05-2021, 03:05 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is online now
 
Join Date: Feb 2006
Location: Sydney
Posts: 16,936
I use -10C for the QHY600m. Works fine and easy to achieve. Low noise.
It probably will achieve that except perhaps on the hottest nights of the year.

Greg.
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 07:37 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
Testar
Advertisement
Bintel
Advertisement
Limpet Controller
Advertisement
Astronomy and Electronics Centre
Advertisement