Larger Sensor Sizes and Better Image Quality

Image sensors used in DSLRs come in a range of sizes. The very largest are the ones used in "medium format" cameras, typically via a "digital back" which can be used as an alternative to a film back. Because of the manufacturing costs of these large sensors the price of these cameras is typically over $20,000 as of December 2007.

With the exception of medium format DSLRs, the largest sensors are referred to as "full-frame" and are the same size as 35 mm film (135 film, image format 24×36 mm); these sensors are used in high-end DSLRs such as the Canon EOS-1D X and 5D Mark III, and the Nikon D800, D4, and D600. Most modern DSLRs use a smaller sensor commonly referred to as APS-C sized, that is, approximately 22 mm × 15 mm, a little smaller than the size of an APS-C film frame, or about 40% of the area of a full-frame sensor. Other sensor sizes found in DSLRs include the Four Thirds System sensor at 26% of full frame, APS-H sensors (used, for example, in the Canon EOS-1D Mark III) at around 61% of full frame, and the Foveon X3 sensor at 33% of full frame.

The sensors used in current DSLRs are much larger than the sensors found in digicam-style cameras, most of which use sensors known as 1/2.5", whose area is only 3% of a full frame sensor. Even high-end digicams such as the Canon PowerShot G9/G10/G11/G12/S100 or the Nikon Coolpix P5000/P6000 use sensors that are approximately 5% and 4% of the area of a full frame sensor, respectively. The current exceptions are the Micro Four Thirds system by Olympus and Panasonic; the Sigma DP1, which uses a Foveon X3 sensor; the Leica X1; the Canon PowerShot G1 X, which uses a 1.5" (18.7 x 14mm) sensor that is slightly larger than the Four Thirds standard and is 30% of a fullframe sensor; and two models from Sony, the RX100 with a 1"-type (13.2 x 8.8mm) sensor with about half the area of Four Thirds and the full-frame Sony RX1.