Just wondered which one would be best to take to Antarctic in December, Just thinking about battery life etc...... simply never been anywhere cold before.
any advice welcome on what to expect.
gerry

Read Michael's equipment report from this year. The 5D isn't all that well weather sealed, so if you're using that be sure to bring something to waterproof it.

Bring both. Bringing one camera that far is never a good idea!

Mike.

When I went on Michael's first tour to Antarctica I took both a 1DsII and a 1Ds .... both worked flawlessly. Although others had no particular problem with the regular batteries I also used a large digital battery which I kept warm under my coat with the power wire running out my sleeve to the camera and it worked great ... didn't have to change batteries once when out on a day's shoot. My wife took along a 5D (with the accessory battery pack) and also had no problem ... so take both as recommended above.

Id say either camera is fine. With any camera watch out for condensation it forms rather heavily when going from cold to warm quickly. Keep the gear in the bag when moving from one extreme to the other.

The 5D has somewhat better image quality than the 1Ds, especially at higher ISO, because it has a newer generation of sensor. But at lower ISO (below 400), the 1Ds is still quite good. For the trip, I would lean toward the 1Ds because it has weather sealing and sturdier construction, and is less likely to quit in inclement weather. The 5D's image quality advantage is meaningless if it quits working when the weather gets bad.

Hi

I have a 20d, I've used it pretty much every day for over 18 months down here and never had any issues, I doubt very much you will have problems with either of yours. I have 2 batteries, I always keep 1 inside my pocket so it's warm and change over if I need to. Once you have swopped batteries put the old one back in your warm pocket and it will recover well enough to use it again if you have too.
Condensation is a real issue, I keep my camera cold pretty much all the time so it's always ready to go.
The best tip for down here is gloves, you need good thin gloves for taking pictures but your fingers get cold very quickly especially if it's windy. When I'm climbing or taking pictures or working outside I have a big pair of mittens that hang around my neck on a chord, I wear thin gloves inside so I can take my hands out, use my camera then pop my hands back into the mittens when they get cold. December on the Peninsular is stunning, 24hr daylight as you go further South and the sun can be deceptively warm, there is little ozone and you get burnt very quickly! Use loads of suncream.
Hope that helps.
Mat.

Lithium ion batteries have significant advantage over NiMH when discharged at low temperatures. So, to get the best of both worlds, you need 1D3. Weather sealed, Li-ion, great high ISO performance. Or, bring both a 5D and a 1Ds like wolfnowl said.