#1  
Old 27-05-2013, 03:00 PM
pmrid's Avatar
pmrid (Peter)
Ageing badly.

pmrid is offline
 
Join Date: May 2008
Location: Bribie Is.
Posts: 3,124
Warming the CCD after use

I am wondering what the conventional wisdom out there is about either just turning cooling off or clicking on "warm"at the end of an imaging session. These options refer to MaximDL but I imagine they are there in other programs as well.
Do you just turn it all off and go to bed or go through a warming cycle before doing that? I suppose there is a theoretical risk of damaging the sensor if it goes from very cold to ambient too quickly.
Peter
Reply With Quote
  #2  
Old 27-05-2013, 04:26 PM
Terry B's Avatar
Terry B
Country living & viewing

Terry B is offline
 
Join Date: Mar 2006
Location: Armidale
Posts: 2,759
I just turn mine off. I read years ago that it is probably only risky to rapidly heat a camera if it is very cold ie liquid N2 cold.
Reply With Quote
  #3  
Old 27-05-2013, 04:52 PM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 6,970
I use AstroArtV5 and an ATiK314L+ for spectroscopic imaging.
The camera seems to warm up OK from -20c upon shut down....
Reply With Quote
  #4  
Old 27-05-2013, 05:45 PM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Hinchinbrook
Posts: 18,150
TBH I used to worry about it but after doing some reading on thermal shockl etc... I just turn everything off and it 'thaws'. Cameras are designed for deep cycling these days. I don't think you're going to break anything if you let it shed its cold naturally. If you force it by blowing hot air or other then I reckon you'd run into serious problems with undue stress on the components.
Reply With Quote
  #5  
Old 27-05-2013, 07:13 PM
Geoff45's Avatar
Geoff45 (Geoff)
PI rules

Geoff45 is offline
 
Join Date: Jul 2006
Location: Sydney
Posts: 2,407
Actually warming just turns the cooler off. It doesn't supply any warming to the chip. The difference between warming and turning the camera off is that you can monitor the chip temp. If you are going to leave your gear set up outside, you can probably just turn it all off and go to bed. Just don' take a cold camera into a warm rom.
Geoff
Reply With Quote
  #6  
Old 27-05-2013, 07:19 PM
Tandum's Avatar
Tandum (Robin)
Registered User

Tandum is offline
 
Join Date: Apr 2008
Location: Carindale, Brisbane.
Posts: 4,112
Quote:
Originally Posted by ghsmith45 View Post
Actually warming just turns the cooler off.
Geoff
No, it slowly backs the power off to 0%. I warm mine, by the time I've shut the doors and put caps on scopes etc power is down to zero and I turn it all off.
Reply With Quote
  #7  
Old 27-05-2013, 08:00 PM
RobF's Avatar
RobF (Rob)
Mostly harmless...

RobF is offline
 
Join Date: Jul 2008
Location: Brisbane, Australia
Posts: 5,493
Theo told me to do a slow warm cycle at the end of the night with my QHY9 (and cool carefully at the start). I suspect it only matters if you have appreciable moisture inside the camera and trying to avoid freezing or condensation. If you have argon or plenty of dessicant then condensation shouldn't come into it, and find it hard to believe thermal shock on sensor should be an issue if you're just removing power and letting sealed chamber equilibrate. No big deal to run a warm up cycle while packing up usually.

Last edited by RobF; 27-05-2013 at 10:50 PM.
Reply With Quote
  #8  
Old 27-05-2013, 08:44 PM
DavidTrap's Avatar
DavidTrap (David)
Really just a beginner

DavidTrap is offline
 
Join Date: Jun 2009
Location: Brisbane
Posts: 2,828
CCD Commander does a slow warm up, but I usually just turn the cooler off if I'm using maxim directly.

DT
Reply With Quote
  #9  
Old 27-05-2013, 08:56 PM
naskies's Avatar
naskies (Dave)
Registered User

naskies is offline
 
Join Date: Jul 2011
Location: Brisbane
Posts: 1,865
The warming function in Maxim only takes a few mins, so I just get it going while I'm covering up the scope - so it's no extra hassle for me.

Interestingly, the datasheet for the KAF-8300 says to "avoid sudden temperature changes". The manufacturer's rated minimum operating temperature is -10 deg C... which I guess most of us using this chip would easily go under in Winter.

http://www.kodak.com/ek/uploadedFile...00LongSpec.pdf
Reply With Quote
  #10  
Old 27-05-2013, 09:11 PM
Geoff45's Avatar
Geoff45 (Geoff)
PI rules

Geoff45 is offline
 
Join Date: Jul 2006
Location: Sydney
Posts: 2,407
Quote:
Originally Posted by Tandum View Post
No, it slowly backs the power off to 0%. I warm mine, by the time I've shut the doors and put caps on scopes etc power is down to zero and I turn it all off.
Maybe it depends on the camera. QSI cameras do not actively warm the chip. See http://tech.groups.yahoo.com/group/Q.../message/10772 by Kevin Nelson, QSI chief exec.
Reply With Quote
  #11  
Old 28-05-2013, 09:54 AM
scagman's Avatar
scagman (John)
Registered User

scagman is offline
 
Join Date: Apr 2011
Location: Kinglake West
Posts: 717
I too was told by Theo to warm my QHY8L up aswell. I usually let it warm while I'm putting caps and things on. It doesn't take too long.

Cheers
Reply With Quote
  #12  
Old 28-05-2013, 10:05 AM
Tandum's Avatar
Tandum (Robin)
Registered User

Tandum is offline
 
Join Date: Apr 2008
Location: Carindale, Brisbane.
Posts: 4,112
Quote:
Originally Posted by ghsmith45 View Post
Maybe it depends on the camera. QSI cameras do not actively warm the chip. See http://tech.groups.yahoo.com/group/Q.../message/10772 by Kevin Nelson, QSI chief exec.
I've not owned a camera that maxim didn't turn the cooling power down slowly.
So that's SBIG, SX, QHY and ATIK.
I can't read that group, you have to be a member to see threads.
Reply With Quote
  #13  
Old 28-05-2013, 10:38 AM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 15,410
Thernal shock concept is something Apogee is usually very concerned about. At least that is the PR line hence their slow cooling rate (30mins to cooldown a U16M camera). By the way that slow cool down can cost you doing your dusk flats if you are running a tad late and start up the camera as dusk is starting. You have to start up that camera say a hour before.

I've read posts by CCD engineers that they have never seen an instance of thermal shock wrecking a CCD.

As pointed out severe temperature shifts may be another story but -35 to 10C or so over 5 minutes does not seem to hurt it. I have my FLI cameras running at -30C all year round so in summer that could be -30C to 25C warm up in 5 minutes. I have not noticed any problems.

The need to slowly cool is false data spread by Apogee. Its obviously false as they don't provide for a slow warm up on their camera. So if you can't make something cool fast like other cameras then you make up some plausible line. Contractors are usually very good at doing that!

Greg.
Reply With Quote
  #14  
Old 28-05-2013, 10:41 AM
DavidTrap's Avatar
DavidTrap (David)
Really just a beginner

DavidTrap is offline
 
Join Date: Jun 2009
Location: Brisbane
Posts: 2,828
QSI thread says "not necessary".

DT
Reply With Quote
  #15  
Old 30-05-2013, 06:20 PM
Peter Ward's Avatar
Peter Ward
Galaxy hitchhiking guide

Peter Ward is offline
 
Join Date: Dec 2007
Location: The Shire
Posts: 6,635
Quote:
Originally Posted by gregbradley View Post
Thernal shock concept is something Apogee is usually very concerned about. At least that is the PR line hence their slow cooling rate

Greg.
Ditto Greg's comments here.

I have never have had a chip fail in my last 25 odd years of astronomical CCD use from a quick cool-down/ warm-up time.

Advertising 101... make-up a difference when there isn't one.
Reply With Quote
  #16  
Old 30-05-2013, 06:52 PM
Terry B's Avatar
Terry B
Country living & viewing

Terry B is offline
 
Join Date: Mar 2006
Location: Armidale
Posts: 2,759
At the temps we use I don't see a problem with turning off the camera and letting it warm itself.
There is a theoretical advantage to slowly cooling the camera. This is to allow any condensation that may form to preferentially form on the cold finger rather than on the front of the CCD. This is only a problem of the camera has a little moisture in it. Mostly it doesn't matter.
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 02:58 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
SkyWatcher Australia
Advertisement
Celestron Australia
Advertisement
NexDome Observatories
Advertisement
Bintel
Advertisement
Lunatico Astronomical
Advertisement
Meade Australia
Advertisement
OzScopes Authorised Dealer
Advertisement
Astronomy and Electronics Centre
Advertisement