If you're bored, with a bit of time on your hands.......

[EchoingWhisper]

Yes, that is to simplify exposure. In reality, it's not like that. A f/2.8 FX and f/2.8 DX lens is not the same size. And ISO 100 on FX and DX is different too. A f/2.8 on FX is similar to a f/2.0 DX (total amount of light and depth of field given that both subjects fills the frame) and and a ISO 200 on FX is similar to ISO 100 on DX (noise level and amplification given that the same light enters the sensor and the same sensor technology/design).

The first part doesn't make sense to me. Shouldn't f2.8 be the same size for a given focal length regardless of lens type ? On a cropped sensor, shouldn't the FX and DX lens yield the same results for a given f stop ? With some light being "wasted" spilling outside of the sensor with the FX.

I might be right or wrong, but read this thread and see if you understand and/or agree with what I think is. http://www.thephotoforum.com/forum/beyond-basics/272347-larger-sensor-just-luxury.html