Editorial

Staff · Issue 65, Mar/Apr 2012 · pp. 4

Editorial 35mm equivalent and film references I was editing Dan Bolt’s excellent review of a new 4/3rds lens for this issue and also Phil Rudin’s article on macro lenses for the same format when I had a sort of lightbulb experience. Let me explain. Traditionally, in order to describe the capability of a lens, the first term that tends to be used is ‘focal length’. Do a Google search for the aforementioned and you’ll be asleep in no time with dreams of light convergence (and divergence), nodal points, focal planes and refractive indices (that’s more than one index, in layman’s terms). Please don’t get me wrong. Focal length is a useful way of describing a lens’s capability but, unfortunately, it doesn’t tell you the whole story because you need to know the size of the image gathering device in your camera. In ‘the old days’ virtually everyone used a 35mm film camera whose format size was …