[fredwu]

Cropping isn't the same as capturing at a different focal length.

[wvbdmp]

Isn’t it optically? Ignoring lens imperfections and assuming infinite resolution, you should get the same image cropping vs. equivalent focal length, no?

[tobyhinloopen]

I think it does, yes. Cropping 25% of the center of a 35mm F/2.0, you'd get the equivalent of a 70mm F/4.0, but with only 25% of the pixels obviously.

[mcdeltat]

I think it's not the same. Changing focal length changes the perspective warping, right? That's why fisheye lenses look crazy, and telephoto lenses "compress" depth. This might be a function of the sensor geometry too, though.

[GiovanniP]

> assuming infinite resolution

this is an assumption that goes against the concept of "f-number" so if one does it, they should not expect to get to anything sensible.