I have been looking for a backup camera for my 5D and am finding a fair number of 10D and 20D bodies for sale on craigslist.
Any opinions between the two considering that a 20D is about 50% more than a 10D?
What are your requirements for a backup camera? I see such great differences between the models in question I don't see the value at any price.
When I want a "backup camera" of course I want a full functional (and like functional) camera that can replace my primary in the even of a failure.. but I also want to be able to use it side by side, hand it off to an assistant as a second camewra in some cases, and I want all the modes, focal lengths, and accepted accessories to translate.
A 5d would make a decent back up to a 5dII.. both are full frame, both have like controls, focal lengths with like lenses are the same, and both are capable of pulling off high quality images despite the improvements of the 5d2. A 20d.. no.. too many differences.. not even the great 7d.. a great camera, but not a "back up" in my mind to a 5d.
5d's are cheap enough these days where picking up a second one isn't that much of a cost burden.. and that it would accept 100% of your accessories might negate any differences in price.
I'm not a fan of using a 5d series to back up a 1 series either.. too many functional differences. I do use both at events, but not in the role of a backup.
I don't think I was very helpful..