Next month I am going to North of Sweden for 6 months. So I'm looking for a new SLR-camera to take photos there. I'm not a professional photographer so I decided to buy an entry level SLR camera - the Nikon D5100 or Canon EOS 600D. Since it can get very cold in Sweden (around -30 degrees) I'm looking for some information about the cold-resistance of these cameras (or other equivalent models you can recommend to me). Has anyone used these models at very low temperatures? How does the camera react at -10 to -30 degrees and does it work after all?
I live in Sweden and I own a Canon EOS 450D. So far I've never had any problems with it in temperatures down to -20 °C (apart from a somewhat reduced battery life).
I wouldn't really worry about your camera not working at sub zero. Every swede I know uses his/her camera in the winter (as well as their cell phones and other electric toys) and to the best of my knowledge the only thing that really stops working are touchscreens which become unbearably slow under -10/-15 °C.
The biggest problem if you really are serious about taking pictures at -30 is that you don't really want to take your gloves off so you should look for a camera where you can change as many settings as possible while wearing you thickest gloves.
The good news is that cameras rarely get damaged by cold, even considerably below their operating limit which is 0C for nearly all DSLRs except some from Pentax.
The bad news is that they stop working quickly. How quickly depends on the ambient temperature and particular camera. What fails first is the batter which looses it ability to supply current while it is cold. Since I shoot below -40C which no camera is rated for, I learn that sometimes you only get a few shots per battery. Spare batteries should be kept warm, say inside your clothes. I usually have one inside my mit to quick access and swap it with the one that stops working which after 15 mins or so tends to warm up enough for a few shots once the spare one gets too cold.
That being said, a proper freezeproof camera makes a huge difference. I shoot each year with at least 30 or so cameras and almost half get used below freezing. A high-end Pentax for example will last steadily for 100s of shots around -20C. If you cannot get a freezeproof model, look for ones with a larger battery. Those take longer to cool down. In some cases you may be able to A/C power them from a generator if you really need to.