Full frame digital SLR
From Wikipedia, the free encyclopedia
A full frame digital SLR is a digital single-lens reflex camera built for a pre-existing range of photographic lenses that takes full advantage of the image circle of those lenses by having an imager that is the full size of the film frame the lenses were designed to cover.
It follows from the above definition that cameras using a lens mount that was designed for digital SLRs (such as the Olympus Four Thirds System) are not full frame cameras. Similarly, a camera using a hypothetical new mount system and featuring a 24mm x 36mm sensor (the size of a 35mm film frame) would not be full frame. In practice, however, the term is often used to simply mean a camera having sensor the same size as a full 35mm frame, while the applicability of the term to four thirds system cameras is a matter of much, often heated, debate.
The chief reason that digital SLRs have not been full frame is to do with the cost of producing such large sensors. As chip sizes get larger, the yield gets drastically lower and thus the prices higher. Moore's law does not apply here; most of the semiconductor industry's advances in affordability have been driven by the ability to make circuits smaller and smaller, but an imaging chip must remain large, and such large chips get cheaper only slowly.
The secondary reason is that digital imaging chips tend to have a much narrower range of acceptance angles than film. Thus, the sensor will be less sensitive to light towards the edges of the image circle, where the light rays are likely to be further from perpendicular. Adding to this, lenses tend to produce poorer results towards the edge of the circle in any case. A smaller image sensor stays within the "sweet spot" of the lens and sensor combination with less difficulty.
While a digital camera for any format could be full frame, in practice all the examples produced have been for 35mm format. The first, fairly unsuccessful attempt was by Contax with a Philips sensor; Pentax worked with this sensor as well, producing a prototype MZ-D, but abandoned it before production. Eastman Kodak produced three models of full-frame camera, but all are now discontinued. The company that has had the most success with full-frame sensors is Canon Inc., whose full-frame sensor cameras have been very successful in the high-end professional photography field. Their newly released model, the Canon EOS 5D, seeks to emulate that success at a much lower price point.
[edit] Other uses
Note, the term full frame is also used to refer to a particular type of charge-coupled device sensor techology in which the sensor elements occupy the entire sensor surface rather than sharing space with associated electronics. The use of such sensors is typically restricted to digital SLRs since they require the use of a mechanical shutter and do not output a continuous image. The two terms are not otherwise related.
[edit] Available full frame digital SLRs
- Contax N Digital
- Kodak DCS Pro 14n
- Kodak DCS Pro SLR/n
- Kodak DCS Pro SLR/c
- Canon EOS-1Ds
- Canon EOS-1Ds Mark II
- Canon EOS 5D
