Digital Single-Lens Reflex
A digital single-
Cutaway of an Olympus E-30 DSLR
Canon EF-S 18-135mm APS-C Zoom lens
Sony ECM-CG50 shotgun-type microphone for DSLR video capture
Like SLRs DSLRs typically use interchangeable lenses (1) with a proprietary lens mount. A movable mechanical mirror system (2) is switched down (exact 45-
Focusing can be manual or automatic, activated by pressing half-
Compared to the newer concept of mirrorless interchangeable-
Nikon D90 in Liveview mode also usable for 720p HD video
Sony Alpha 99, full-frame digital SLT camera
An APS-C format SLR (left) and a full-frame DSLR (right) show the difference in the size of the image sensors.
Pentax is a brand name used primarily by Ricoh Imaging Company
Canon EOS 60D APS-C digital SLR with lens removed.
The lenses typically used on DSLRs have a wider range of apertures available to them, ranging from as large as f/1.0 to about f/32. Lenses for smaller sensor cameras rarely have true available aperture sizes much larger than f/2.8 or much smaller than f/5.6.
To help extend the exposure range, some smaller sensor cameras will also incorporate an ND filter pack into the aperture mechanism.
The apertures that smaller sensor cameras have available give much more depth of field than equivalent angles of view on a DSLR. For example a 6 mm lens on a 2/3″ sensor digicam has a field of view similar to a 24 mm lens on a 35 mm camera. At an aperture of f/2.8 the smaller sensor camera (assuming a crop factor of 4) has a similar depth of field to that 35 mm camera set to f/11.
Drawing showing the relative sizes of sensors used in current digital cameras.
Kodak DCS 100, based on a Nikon F3 body with Digital Storage Unit, released in May 1991.