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Old 11-08-2012, 08:22 PM
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troypiggo (Troy)
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Join Date: Nov 2008
Location: Brisbane, Australia
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The focal length doesn't change. A 10mm focal length lens is always a 10mm focal length lens. It's just that on a crop sensor, ie smaller than a full frame sensor, doesn't collect the same area of light, so the apparent field of view is narrower by whatever fraction of a full frame sensor it is (1.6x for APS-C). But it's still 10mm focal length.

http://www.bobatkins.com/photography...nd_lenses.html

F-ratio is not affected.

Depth of field is subtly affected, because it's a function primarily of f-ratio and distance to subject, but also circle of confusion, sensors etc do come into it.
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