crop factor

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crop factor

The ratio of the focal length of a digital camera lens to a 35mm still camera lens. The crop factor is used by experienced photographers, who want to know the field of view of a lens on a digital camera as compared to a lens on an analog 35mm camera, which they have been using for years.

The Sensor Is Often Smaller
The size of a 35mm film frame is 36 x 24mm. In high-end digital cameras, the sensor may be the same size ("full-frame"); however, most digital camera sensors are smaller (see table below). The difference in size creates the crop factor, also called the "lens factor," "focal length conversion factor" and "lens multiplier."

Multiply by the Crop Factor
As an example, a crop factor of 1.5 means an 18mm focal length on the digital camera is equivalent to 27mm on a 35mm camera (18 times 1.5). See APS-C, focal length and f-stop.

STILL CAMERA FRAME SIZES                  Approximate                  Size in MMAnalog Film       (Rounded)

  35mm              36 x 24 

  APS-C             25 x 17
  APS-H             30 x 17
  APS-P             30 x 10


  Digital Sensor

  Canon (APS-C)     22 x 15
  Canon (APS-H)     29 x 19

  Four Thirds       17 x 13

  Foveon            21 x 14

  Nikon CX          13 x 9
  Nikon DX (APS-C)  24 x 16
  Nikon FX          36 x 24

  Pentax (APS-C)    24 x 16

  Sony (APS-C)      24 x 16
References in periodicals archive ?
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