Lens Specifiaction - Quick Question

[aby]

Normally a lens has its specs written as
35-80mm f/4.0-5.6 or
50mm f/2.0 Lens
How does this translate in terms of Focus, Zoom, Aperture etc.

Also, in the digital world, we get 3x, 4x zoom. How do we convert from 'mm' zoom to 'x' zoom.

Thanks.

[another view]

35-80mm would be about a 2.3X zoom. The "X" doesn't have anything to do with the focal length in mm, it's just how much range it has mathematically. 35 x 2.3 = 80 (approximately)

If only one focal length is listed (like 50mm f2.0) then it's a prime lens, not a zoom. It only has one focal length. The maximum aperture is the "f" number, in this case f2.