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  #21  
Old 08-02-2009, 09:29 PM
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Oh yes you have the added advantage of one crook pixel stuffing up a whole vertical line! When I was at the Synchroton in Japan Professor Sukabi showed me his CCD detector for photons from xrays. For time dependant experiments he was only using half of the CCD to collect and then downloading the data to the unexposed part of the CCD. This data was then read by the much slower bottleneck before the next lot of data was collected.

Bert
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  #22  
Old 08-02-2009, 09:32 PM
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Watercooling hoses need not be stiff.. you're just using the wrong hosing if it is... Tygon make the best hosing around, its expensive at $25 per meter, but its what hospitals use for all their hosing needs.. so thats the stiffness solve... from there, norma hose clamps are $1 each at mitre 10... Theres that solved.. Watercooling of anything need not be considered dangerous, its as safe as houses provided you think before you execute the design.

I myself have watercooled many MANY computers in my time, with hoses going between the cpu/graphics card, ram and hard drives.. all up a $6000 computer with 1.2L of water inside it... never once had a single issue...

Alex.
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  #23  
Old 08-02-2009, 09:38 PM
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Monte Wilson of ASNSW water cooled his SBIG STL11000 by rigging an amazing set of gravity fed tubes from the water tank tower at the imagers house at Wiruna. He ran tubing under the ground through his camera and up to the tank, had to dig a trench and all....So extra cooling is deffinitely desirable given the lengths some will go to get it but not having to use water cooling in the first place and still having better cooling is..?..even better! .

Mike
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  #24  
Old 08-02-2009, 09:49 PM
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I have come to the conclusion we are all nuts. Whatever works for you folks!

Just keep those images coming

Bert
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  #25  
Old 08-02-2009, 10:03 PM
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Quote:
Originally Posted by avandonk View Post
I have come to the conclusion we are all nuts. Whatever works for you folks!

Just keep those images coming

Bert
Nuts? who's nuts? I resemble that comment

What's wrong with loading your car up to the hilt and traveling 4 hours to a dark sky, spending 2 hrs setting up a whole lot of scopes, mounts, cables and cameras and then staying out in the dark pointing at the same spot of sky for three nights in a row with little sleep during the day, then spending 2 hrs packing up and 4 hrs driving home and then unpacking the car....only to have to do it all over again next clear dark night.....?

http://www.pbase.com/strongmanmike2002/wiruna_trips

I'm not nuts...am I?
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  #26  
Old 08-02-2009, 10:05 PM
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Quote:
Originally Posted by strongmanmike View Post
....... some may be in a position to upgrade and this is one hell of a good reason to if you were thinking about it.

Mike


Ok That's a good reason.

I can think of another CCD that has:
  • Full Frame Image Buffer
  • Multiple A/D Channels
  • Image and Guide While Downloading
  • Internal and External Self-Guiding (with Remote Head)
  • Simultaneous Dual CCD Guiding
  • Differential Guiding
  • Continuous Guiding During Autograb
  • Adaptive Optics Control with Internal or External Guider
  • -50 degrees C Delta Cooling with Air Only
  • Water Cooling Ready
  • Even-illumination Mechanical Shutter
  • Gas Purge Valve on CCD Chamber
  • User Rechargeable Desiccant Plug
  • Variable Speed Fan Control
  • Focus Mechanism for Tracking CCD
  • Opto-isolated Relays for Telescope Control
Doh! *I* Better hit the gong before its too late
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  #27  
Old 08-02-2009, 10:12 PM
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Originally Posted by Peter Ward View Post


Ok That's a good reason.


I can think of another CCD that has:
  • Full Frame Image Buffer
  • Multiple A/D Channels
  • Image and Guide While Downloading
  • Internal and External Self-Guiding (with Remote Head)
  • Simultaneous Dual CCD Guiding
  • Differential Guiding
  • Continuous Guiding During Autograb
  • Adaptive Optics Control with Internal or External Guider
  • -50 degrees C Delta Cooling with Air Only
  • Water Cooling Ready
  • Even-illumination Mechanical Shutter
  • Gas Purge Valve on CCD Chamber
  • User Rechargeable Desiccant Plug
  • Variable Speed Fan Control
  • Focus Mechanism for Tracking CCD
  • Opto-isolated Relays for Telescope Control
Doh! *I* Better hit the gong before its too late
Wha?..all that and STILL only 50degC cooling? Ah sigh...we still gotta get out the buckets and pumps and tubes and fumble in the dark :rofl :


Com'on Pete loosen up man

Certainly sounds like a beaut camera

Mike
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  #28  
Old 08-02-2009, 10:24 PM
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Quote:
Originally Posted by strongmanmike View Post
....all that and STILL only 50degC cooling? ...
Hey I'm cool....

But for the newbies out there, delta T's are rarely constant (ambient temp and air flow can have a big influence) and often *reduce* once the thermal cooling/inertia of the camera head is lost after being heated by the peltier stack. (thermal runaway can happen at that point...not good)

I've personally found bugger all difference in well calibrated images taken at -15 or -25 degrees. The key is the quality of the calibration frames rather than the CCD temperature set point.
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  #29  
Old 08-02-2009, 10:54 PM
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Hey I'm cool....

But for the newbies out there, delta T's are rarely constant (ambient temp and air flow can have a big influence) and often *reduce* once the thermal cooling/inertia of the camera head is lost after being heated by the peltier stack. (thermal runaway can happen at that point...not good)
You may be right Peter but luckily I have been able to image at a chip temperature of -35C on each and every night I have imaged since receiving my ProLine in mid 2007 right throuh summer, autumn, winter and spring and in fact could have gone colder on "every" ocassion and no water pumps and tubes in sight, so any variations in the dalta cooling of the FLI ProLine haven't been great enough to stand in my way in sunny Newcastle.

Mike
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  #30  
Old 08-02-2009, 11:00 PM
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Quote:
Originally Posted by Peter Ward View Post
I've personally found bugger all difference in well calibrated images taken at -15 or -25 degrees..
Ditto........
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  #31  
Old 08-02-2009, 11:29 PM
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For those with further interest in this thread, Steve Cannistra has done some excellent work in this area. You can also download an excel spreadsheet from his site that helps you play around with some real world values

His take?

CCD cooling beyond -15 to -20 C produces minimal gains in the functional dynamic range for most imaging sites, because the sky flux becomes the limiting factor in this situation.

Roughly translated.....a dark site is way more valuable than a super cold chip! (Why do I have a backyard observatory again?? Doh! )
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  #32  
Old 08-02-2009, 11:41 PM
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Mike, turning the power off at -35 is fine, as it will take time to warm up. But going from 26.5 deg to -35 in a minute or 2, isnt a good idea. Kodak may be basing there response on a warm up temp range, and not out right "Flat out" hot to cold thermal transfer.
Still, gota love them cameras..

Theo
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  #33  
Old 08-02-2009, 11:47 PM
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Bah humbug! You SBIG clowns are just jealous, ya'll say anything, like the neo Christians in the US have whole museums to varify Genisis
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  #34  
Old 08-02-2009, 11:53 PM
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Mike, turning the power off at -35 is fine, as it will take time to warm up. But going from 26.5 deg to -35 in a minute or 2, isnt a good idea. Kodak may be basing there response on a warm up temp range, and not out right "Flat out" hot to cold thermal transfer.
Still, gota love them cameras..

Theo
Hmm? wonder how I'd know if something went wrong?..a big black jaggered line on the downloaded frame? I've been setting it at -35C for a year and a half now summer, winter, autumn and spring and it gets there in just a few minutes everytime...?
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  #35  
Old 08-02-2009, 11:57 PM
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Ahh now Mike.. Just because SBIG users get APODs... no need to fire up that old chestnut.. In all seriousness.. nobody can say that cooling that far is not an extreme achievement, although what does it mean in the real world? (That was not rhetorical.. I have no idea.) I know no camera I own will cool to -35c in a 26c ambient temp.. not even close... so yes. The FLI cooling wins against my arsenal of cooling setups.
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  #36  
Old 09-02-2009, 12:15 AM
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Ahh now Mike.. Just because SBIG users get APODs... no need to fire up that old chestnut.. In all seriousness.. nobody can say that cooling that far is not an extreme achievement, although what does it mean in the real world? (That was not rhetorical.. I have no idea.) I know no camera I own will cool to -35c in a 26c ambient temp.. not even close... so yes. The FLI cooling wins against my arsenal of cooling setups.

Ah Alex I think you have my measure, I'm a sarcastic fun loving bustardo fisherman and Peter SBIG always bites, can't help himself....like brown trout in a trout farm (or do they use nets there?). I was just posting about the cooling cause I thought it was ..?.."cool?" but the brown trout just had to jump outa that water again like always

Mike
Super chip cooling rules ...dark skies are a myth
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  #37  
Old 09-02-2009, 12:23 AM
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DOH those pesky fussy moderators, moved us again
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  #38  
Old 09-02-2009, 11:23 AM
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..Aye carrumba.

Clandestine promotions for FLI aside, this could have been an interesting discussion.

As for my spin? Dark sites do far more for CCD S/N ratios than almost anything else. Really accurate tracking/guiding comes next. Everything else? Well I suppose that's why we have these discussions.......
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  #39  
Old 09-02-2009, 04:40 PM
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I've taken shots with a DSLR from dark skies that easily rival my CCD shots from light polluted city skies... In that situation, cooling is out of the equation, dark skies did all the magic there.
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  #40  
Old 10-02-2009, 08:04 PM
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Ah but Peter there are more advantages to super cooling than merely noise.

As you know the STL11 KAI11002 chip along with others in the KAI family suffer from vertical lines caused by hot pixels. Now theoretically these should dark subtract out or a bias frame should remove it etc but often they do not. They then become a real pain to remove if you can during processing.

Richard Crisp - the arguer, has demonstrated clearly in a paper that high cooling gets rid of these lines. They don't fade out until you hit -30C and beyond.

Merely going down to -10C will not and they will be a pesk when you process your images.

I know from long experience the STL11 ideally is operated at -35C. It is quite noisy at -10 and even -20C isn't ideal. It starts to shine at -35C.

Yes dark subtraction works but it now becomes critical that it is done excellently with lots of darks sigma reject combined and with accurate matching temps and exposure times.

Cold chips have practically no noise in the first place, dark subtraction almost becomes only if you want to and certainly less critical and exact matching of darks is less important and use of adaptive darks is feasible with little or no difference to exact matching.

In my opinion excellent cooling is important and gets rid of a lot of problems that complex processing requires otherwise having used different cameras with different cooling abilities.

Of course a dark site is more important again but if you had 2 cameras and all other things were equal then the one with the superior cooling should be your choice.

Greg.



Quote:
Originally Posted by Peter Ward View Post
For those with further interest in this thread, Steve Cannistra has done some excellent work in this area. You can also download an excel spreadsheet from his site that helps you play around with some real world values

His take?

CCD cooling beyond -15 to -20 C produces minimal gains in the functional dynamic range for most imaging sites, because the sky flux becomes the limiting factor in this situation.

Roughly translated.....a dark site is way more valuable than a super cold chip! (Why do I have a backyard observatory again?? Doh! )
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