Don't confuse DSLRs with the new, fast-growing category of hybrid cameras. These are fine cameras that also offer interchangeable lens systems, but they use an electronic viewfinder instead of the mirror to compose your image.
The DSLR camera world is divided into full-frame sensors and reduced-size APS-C sensors.
Cameras with full-frame sensors start at about $2,000. They appeal to pros and advanced amateurs because they offer the highest image quality. These cameras also usually capture more frames per second, which is critical in sports and wildlife photography. Top DSLRs are also more weatherproof than entry-level DSLRs.
A full-frame sensor is the same size as traditional 35mm film - 24 x 36mm. Unlike cameras with smaller sensor sizes, there is no magnification factor when changing lenses. A 50mm lens behaves like a 50mm lens.