Focal length conversion chart – click for larger view
If you’re like me, you’ll always have trouble knowing which focal lengths are equivalent across different formats. There’s a formula for converting it based on the diagonal of the frame, but I couldn’t remember it. Fortunately, viewcamera.com solves the problem with a chart that lays it all out.
Just choose your focal length along the left hand bold column. Then read across to find its 35mm equivalent for your medium or large format. For example, a 150mm wide angle lens for a 6×6 format camera is equivalent to a 96mm lens in 35mm format. Since I know that’s between a standard lens and a short telephoto, I know that if I buy that 150, I’ll have a nice portrait lens.