[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.

[john2x]

Cropping the centre of a fisheye photo will look the same as a normal or telephoto lens if they are taken at the same distance (the crop will have less resolution of course)

[mcdeltat]

After looking it up, yes you are right, they are the same. I was thinking of changing the distance to subject instead.

[Anotheroneagain]

Fisheye lenses look crazy because they are deliberately made that way. Rectilinear lenses don't do it.