Values indicate the multiplicator effective for viewing angles of full frame lenses, i.e. by mounting a full frame 50mm lens to a camera with full frame sensor, the focal length of 50mm will offer a diagonal viewing angle of ~46°. The crop factor is 1.0x, since the ratio of sensor size : projected image of the lens on the sensor ≙ 1 : 1. Mounting full frame lenses to cameras with smaller sensors will crop the lenses' projection on the sensor's effective surface, thus the viewing angle is reduced.
* Canon XL. Canon did not publish too much details. The sensor was specified to be 1/3" and the crop factor using the Canon XL-EF Adapter was said to be 7.2x. The camera records in 16:9. Also read dvinfo.net (using these values gives a crop of 7.09x).
** Canon APS-C sensor sizes vary from 22.2 x 14.8mm to 22.7 x 15.1mm, while by watching the evolution of their sensors a size of 22.3 x 14.9mm has been used in all later models. Many other companies use sizes of 23.7 x 15.6mm (Ø28.4mm) instead, resulting in a crop factor of 1.5x.
*** Canon APS-H sensors also vary in size. The above size is valid for EOS 1D Mark I, II and IIN. Mark III featured a sensor sized 28.1 x 18.7mm, Mark IV a sensor sized 27.9 x 18.6mm and the old EOS D6000 even a sensor sized 27.6 x 18.4mm.
**** Digital full format derives from old 35mm film standard. Most of Canon's full frame cameras came with sensors sized on par with this specification, with the exception of EOS 1Ds Mark I (35.8 x 23.8mm) and EOS 5D Mark I (35.8 x 23.9mm).
Doing the math yourself: Ø = √W2 + H2.
To calculate the crop factor requires some preliminary considerations about your specific setup. Sensors feature all kinds of different aspect ratios - DSLRs' sensor ratio usually is 3:2, Super 35 is 4:3, Canon's XL series came with 16:9 sensors, industrial cameras in some cases feature a 1:1 ratio etc.. There is no big challenge in calculating crop of sensors of identical ratio. The mess starts when mounting lenses to cameras with other aspect ratios. The lens will always serve the same image circle - in case of full frame lenses always of a diameter above 43.3mm, which a myriad of aspect ratios can be fitted in. Now depending on your needs the crop factor will differ depending on being based on diagonal viewing angle or horizontal viewing angle.
Examples of calculated crop:
The crop factors in the table above and on all other pages here are based on the horizontal AOV, if not stated otherwise.
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