Most people are using Canon cameras with Nikon lenses and using Dragonframe as software. The reason for Canon cameras over Nikon cameras is because Nikon cameras can get hot and shut themselves off if you leave them on live view for very long. The AF Canon lenses will not work for stop motion. You need a manual lens. Most people buy old Nikon lenses that are Nikkor AI or AIS. These are manual focus and manual aperture. You will need a Nikon to Canon adapter for the lens. You cannot reasonably use old Canon lenses because they will require an adapter and in order for them to focus to infinity the adapter has to have a corrective lens inside. This corrective lens will degrade your image. This is why you don't see stop motion people using the old Canon FD lenses on Canon cameras. As to which Canon camera to purchase, that will depend on your budget. The main thing to think about is having your stop motion software with live view. Here is a link to Dragonframes camera list: http://www.dragonframe.com/camera.php
You want to be sure an purchase one of the cameras on the live view list. I just purchased a used Canon 40D off Ebay. You can expect to pay around $350 for this camera. Be sure and check out accesories! There may be different priced cameras, but look at the accessories when settling on the price. You will want a battery, a charger, a cable to go from camera to computer usb port. You will want to buy a power supply so you can have continuous power to the camera. You will use up the batteries too quickly to rely solely on batteries. You might want to buy a remote switch, but you don't have to have it with Dragonframe software. You will need a Nikon to Camera adapter. About lenses, most folks are using 28mm and 55mm micro Nikkor lenses AI or AIS. I just purchased 2 used ones off Ebay. A Nikon 28mm is about the equivalent of a 50 mm lens on a 35 mm camera and the 55mm lens is about the equivalent of 85mm lens. This is why you see the 28mm lens being used. It is not recommended to buy a 35mm lens.
For information on this subject, you can check out this thread: http://www.stopmotionanimation.com/foru … nt%3A23382
Hope this helps!