All types of cameras have been chosen to fly in amateur rockets to capture aerial images, including 110-format, Disc cameras and Polaroid cameras, but the most popular and successful format is 35mm (point and shoot or SLR/DSLR). 35mm-format cameras are sufficiently compact for the purpose whilst also giving good-quality images. It is more or less essential for a camera to have an electronically controlled shutter mechanism - ie the shutter can be released by an electronic circuit connected via an appropriate secure connector on the camera body. A simple timer circuit can then be utilized to fire the shutter at chosen intervals. Clearly film cameras must also have a motorized film transport mechanism to allow numerous images to be taken during a single flight.
SLRs are the best choice in many ways, not least because they are very controllable and flexible, and feature high shutter speeds and fast film advance. However they are also heavier and more expensive that their compact and automated point-and-shoot equivalents. The type of camera used depends upon weight and space limitations, and of course cost. Larger rockets are better suited to the use of SLRs or DSLRs but the price of a crash increases quite a bit! If using an SLR, set the shutter speed to 1/100 sec or faster to reduce motion blur to a minimum, and set the focus mode to manual to avoid the camera hunting for focus. Using a reasonably fast film helps to keep shutter speeds high but of course also produces slightly grainier images.
Automatic point-and-shoot cameras are generally smaller, lighter and less expensive than SLRs but many do not have shutter speeds faster than about 1/400 or 1/500 sec so motion blurring can be a problem. Cheaper compact cameras may also lack a manual mode to allow the fastest shutter speeds to be selected. Film versions tend to have slow film transport mechanisms that limit the number of exposures taken during ascent, but inexpensive digital cameras do not have this problem.