A couple of questions regarding crop fator

Discussion in 'Photography Beginners' Forum' started by DVGuru, Nov 10, 2007.

  1. DVGuru

    DVGuru TPF Noob!

    Apr 6, 2007
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    1) Do the focal lengths on the Canon EF-S lenses account for the crop factor? For example, is 18 mm on an EF-S lens really 18 mm, or is it still 28.8 mm like it would be on an EF lens?

    2) Does the crop factor have an effect on the f/stop also?

  2. Alex_B

    Alex_B No longer a newbie, moving up!

    Aug 30, 2006
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    1) 18 mm is always 18 mm, with or without "crop factor", it never becomes 28.8 mm.

    The only thing which is sometimes done, is that an 35mm-equivalent focal length is stated, which refers to the effective angle of view of the lens when used with a smaller medium such as a small sensor. But this equivalent is never printed on the lens.

    If you go to the small point and shoot cameras, even they have their (very short) focal lengths printed on their lenses. Only on the camera it might state the equivalent to 35mm cameras.

    2) not really, since to get the correct exposure on the sensor, sensor size does not play a role.

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