sentences:  For example, when talking about a 14 mm lens for a Four Thirds System camera, one would not only indicate that it had a focal length of 14 mm, but also that its "35 mm equivalent focal length" is 28 mm.This way of talking about lenses is not just limited to SLR and DSLR lenses; it is very common to see this focal length equivalency in the specification of the lens on a digicam.Values in the following table are approximate, and apply to rectilinear lenses only, not to fisheye lenses.