Accessories - System cameras, such as most professional SLRs, are designed in such a way that parts can be added and changed to suit a particular job. To increase the versatility of a system camera, some manufacturers offer a wide range of accessories. What counts as an accessory rather than a true part of the system is a matter of personal definition, but generally, they include the following: viewfinder heads, screens, triggering devices, interchangeable backs (such as a data back), straps, mounting extensions, spirit levels, panoramic heads, and so on.
