What do focal lengths mean?
When I got my DSLR it came with a standard kit lens - a Canon EFS 18-55 IS. The 18-55 bit refers to the lenses "focal length". So what's that all about then? The focal length of a lens is the distance between the "middle" of the lens and its focal point. The focal point is the spot where the light passing through the lens converges, and for a properly focused image this point should fall on the camera's sensor (or film, if you're not using digital). The middle of the lens is a bit of a grey a...
