Does 2mm in Focal Length Matter?

by | Aug 30, 2018

Today’s Post by Joe Farace

Recently I did an informal test, comparing 15mm lens with 17mm mirrorless camera lenses while photographing the annual Chenango Car Show and was surprised, or maybe not so surprised, at the results.

The lenses in question were the Rodney Dangerfield Olympus 17mm f/2.8 lens (top image) that was mounted on my Panasonic Lumix GF3. This compact lens has an angle-of-view of 65 degrees. Angle-of-view is often used interchangeably the field-of-view and refers to the angle over which the camera’s sensor sees through the lens and is usually given as the diagonal of the image or sometimes the vertical and horizontal directions.

The other lens was the Voigtländer super-wide Heliar 15mm lens (bottom image) that was mounted via an inexpensive ($20) Fotodiox adapter to my beloved Lumix Gx1. The Voightlander, on the other hand has an angle-of-view of 110 degrees, not quite double that of Oly’s 17mm lens.

Yet all the equivalents in the world tell you that one is really what amounts to a 34mm lens compared to a 30mm lens, which doesn’t sound like much either. Take a look at the above photo and decide for yourself.