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Sensor size matters on digital cameras

Comparing sensor sizes, top to bottom: point-and-shoot, APS-C, full frame, 33x44 mm medium format
Comparing sensor sizes, top to bottom: point-and-shoot, APS-C, full frame, 33x44 mm medium format
Gene Forrest

Twenty-five years ago, when film cameras were all the rage, many professional photographers, and more than a few serious amateurs, used medium format cameras for a lot of their work. Those cameras created negatives that might be 60x70 mm in size (including borders), compared to the 24x36 mm negatives made by 35mm cameras.  Professionals liked medium format, because the larger the film, the sharper the picture, all other things being equal.

The same is true with the sensors in today’s digital cameras—the larger the sensor, the better the picture quality. Bigger sensors allow for bigger pixels. And bigger pixels can gather more light and produce more voltage, so they are less prone to electronic noise. Bigger pixels also allow for a higher dynamic range, which means there is less detail lost in the highlights and shadows, a problem that photographers often refer to as “clipping.” Moreover, a high dynamic range is better at revealing subtleties of color and tone.

The following is an ordering of today’s digital cameras by size of sensor, going from smallest to largest: 1) camera phone  2) point-and-shoot  3) micro four-thirds  4) four-thirds  5) APS-C  6) full-frame  7) medium format  8) large format.

The chart in the picture shows the relative sizes of some common sensors. Most digital SLR’s made by Canon, Nikon, Pentax, and Sony use APS-C sensors that are approximately 16x24 mm. But a few of the more expensive cameras have 24x36 mm sensors, the same size as a 35mm negative. This sensor size has been dubbed “full-frame.”

While most people are astounded by the quality of the images coming from full-frame D-SLR’s, some professional photographers are seeking even higher quality. They are turning to medium format digital cameras, which look like the old medium format film cameras, and are made by some of the same companies.

Sensors in these cameras, which are sized from 33x44 mm up to 40x54 mm, may have up to 2.5 times the surface area of a full-frame sensor and twice the dynamic range. They usually have 30-60 megapixels, compared to 12-24 found on “35mm style” cameras. Photographers who have “money-is-no-object” clients are willing to spend the money for the superlative quality. How much money? Perhaps $40,000 or more, including lenses.

More information is available at these manufacturers’ websites. Hasselblad, Mamiya, Pentax, Phase One.

Some photographers have gone full-circle, from medium format film cameras to medium format digital.