Crop Factors

Started Sep 20, 2008 | Discussions thread
Sean Nelson
Sean Nelson Forum Pro • Posts: 12,807
Re: Crop Factors

LaciX wrote:

I’m maybe wrong, but all smaller than full-size sensor cameras
employing reduction lenses. The, so called “tele lenses” used on this
cameras are really cropped wide fields.

I'm a little perplexed by your post, but I think what you're trying to say is that a telephoto lens on a small-sensor camera has a relatively short focal length (35mm for example) than a lens with an equivalent field of view on a camera with a larger sensor (250mm as an example).

This is of course true. But you should understand that a telephoto lens on a small-sensor camera produces exactly the same perspective (ie, "compressing effect", as you call it) as a telephoto lens with the same field of view on a large-sensor camera. This is true even though the lenses may have radically different focal lengths.

For example, a 150mm lens on a 35mm camera, a 100mm lens on an APS-C camera, and a 20mm lens on a small-sensor camera (with a crop factor of 7.5) will produce images that all look the same (except for depth of field and potential IQ differences due to the lens design and sensor noise levels, etc).

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