35mm L lenses on APS-C sensor cameras?

[ChadS]

@Rubar Yes that's basically it. You could also say "the crop camera will create an image that's a cutout of the full frame image." If I mount a lens in one spot and shoot with a full frame camera I'll get one image. With a crop sensor I'll get a different image. However, if I were to print the full sensor image I could make the same picture as the crop camera shot simply by cutting all four sides of the image the appropriate amount.

That's slightly different than zoom but for your purposes it's a close enough explanation.

[neuroanatomist]

I think I’m starting to get it. Thanks to all of you!
Just to clarify, please tell me am I right or wrong stating:
With the same 200mm L lens I get on 35mm (full frame) camera wider frame and on APS-C will get a more close-up (more zoom).

That works.

You could also say "the crop camera will create an image that's a cutout of the full frame image."

I think Chad's phrasing is more accurate. You're not getting any more real magnification with the crop sensor, just cropping away the outer part of the image circle projected by the lens. Here's a visual illustration of that:



The circle is what the lens 'sees', the red rectangle is the image captured by a FF sensor, the blue rectangle is the image captured by an APS-C sensor, all from the same lens.

However, depending on the sensor you might get more apparent magnification. For example, if you use that 200mm lens on a 5DII and crop it to the frame you'd get with APS-C, you have an 8 MP image. So if you used a old 20D (an 8 MP camera) instead of the 5DII, you'd get the same picture as the cropped 5DII image. But, if you use a 600D with an 18 MP sensor, that mountain in the blue rectangle would cover a lot more pixels of the 600D sensor than the 5DII sensor, so if you viewed both side-by-side on the computer monitor at 100% size, the mountain would be 'bigger' when shot with the 600D.