[Gratris]

Hi all,

I have a crop sensor dslr, a canon.

If i was to buy an EF-S lens, say a 20mm, would it be just that, 20mm?
If I was to buy an EF lens at 20mm would it fit on a crop sensor camera and would it still be 20mm or would it be effectively 32mm because of the 1.6 crop factor?

Are EF-S lenses designed for crop sensor camera's and EF lenses for full frame cameras?

If so, are the two interchangeable with crop sensor's and full frame dslr's?



Thanks
Gratris