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Old Feb 20, 2005, 4:07 PM   #11
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Good research quality astro-cams are CCD based and use a peltier cooler or liquid nirtogento drop the CCDintothe -30 -40 range or further.

It does help them to do long exposures, but they are specialized cameras that require multiple long exposures through some very expensive filters to get each of the four LRGB channels.

Price wise a SBIG 1mp Research STL-1001E is about 12,000$us a 6.3mp Research STL-6204E is 33,000$us.An LRGBC filter set is 695$us.

A CCD sensor starts with no charge in the sensor sites and the photons build in each photo-site as time goes by.

A CMOS sensor starts with a full charge across the sensor and it depletes as light hits it, or over timethe chargealso dissipates, so they are not very good at long exposures.

Not sure what help it would do to aCMOS based camera,CMOS are not designed for very long exposures.

So it depends what type of sensor is in your camera, most probably all you would get is frost bite, and at these temperatures possible a really frozen and damaged LCD.

Peter.
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Old Feb 22, 2005, 2:35 PM   #12
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I live in Alaska, so I often use my camera in -10F and colder.
I have used my DiMAGE 7Hi at -30F for about an hour taking pictures of Northern Lights, and taking about 20 shots it went through one fresh set of 2300Mah AAs.
I then sealed the camera in its case (zipped totally shut all the way around) and let it sit at room temperature for a good hour before opening the case.
Cameras work well in cold temps. :lol:
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Old Feb 22, 2005, 4:17 PM   #13
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Yep, it's battery which "dies" fast.
With my Minolta 7i NiMHs become completely frozen under five minutes.
Sealed lead acid batteries are good and cheap external batteries for outside use in cold.
Digicams draw so small current that it is photographer which freezes before battery.

I mean these temperatures...
http://koti.mbnet.fi/~tuunaes/Images...n%20winter.jpg
http://koti.mbnet.fi/~tuunaes/kuvat/PICT2500.jpg
http://koti.mbnet.fi/~tuunaes/kuvat/PICT2536.jpg


PeterP wrote:
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Good research quality astro-cams are CCD based and use a peltier cooler...

It does help them to do long exposures, but they are specialized cameras that require multiple long exposures through some very expensive filters to get each of the four LRGB channels.
Couple examples from Astronomy magazines I have on table:
H-alfa and RGB filters, exposures 160, 20, 20 and 20 minutes

LRGB: 40, 40, 10 and 32.
LRGB: 75, 10, 20 and 20
LRGB: 90 and 20 for each color channel.
LRGB: 120, 50, 50 and 60

Or how about some stacking?
8 30min H-alfa frames and 3 frames for every color with 10 (R), 10 (G) and 16 (B) minutes
Or other one with "total" exposure time of 12 hours.

You have to also remember taking dark frames and "flat field" shots.
:G
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Old Feb 22, 2005, 7:20 PM   #14
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Yes, one or two pictures becomes an all night affair :-)

I don't see why there are no external battery packs you can keep inside you coat and just run a wire out to the camera. Something that is available for film based SLR's.:!:I actually called Canon customer support about it and they said they don't make or support such a product for the 20D. :sad:

PeterP
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Old Feb 25, 2005, 6:34 PM   #15
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PeterP wrote:
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Yes, one or two pictures becomes an all night affair :-)

I don't see why there are no external battery packs you can keep inside you coat and just run a wire out to the camera. Something that is available for film based SLR's.:!: I actually called Canon customer support about it and they said they don't make or support such a product for the 20D. :sad:

PeterP
hmmmm. . .I know they are out there for my 7Hi:G.
I doubt something like http://www.shentech.com/wimbapafordi.html would work, but it might be worth a try :lol:
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Old Feb 28, 2005, 1:24 AM   #16
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I reckon that it's important to not operate the camera for a long time when you take the camera from an cold environment into a warm environment...like stepping inside your warm lodge after a trek around the snow fields. That's because water can condense from the air and then get onto water-sensitive parts of the camera...like the electronics etc.

But also, some of lubricants in some cameras (for the zoom lens maybe) might not work too well below a certain temperature...so this could be an issue...like cause a mechanical fault or something.

I'm not sure what effect the cold can have on the LCD...ie whether or not it's enough to cause the LCD to fail. Maybe the manufacturers of those screens might have something to say about that. And then there's the issue of batteries being affected by the cold. But at least if the camera's designed properly when the batteries go dead, then the camera will just cease to operate...but won't undergo catastrophic failure.
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Old Feb 28, 2005, 2:48 PM   #17
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Kenny, good point about the lubricants. I hadn't thought of it, but it makes perfect sense. That certainly could be a serious issue.

PeterP,
DigitalCameraBattery.com supports the 10D, I bet they support the 20D. Their battery pack, while a bit big, is amazingly good and would allow you to keep the battery inside your jacket and run the cable out to the camera.

Eric
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