Since we've decided to abandon our auto-focus, I'd like to set up a manual focus gauge. I think I remember you saying that it was 35mm from the bottom of the knurled part of the lens holder to the optimal work surface. Can you verify this for me? Or correct me?

Quick Answer:

The expected distance from surface to the knurled chamfer is 39mm. It is best to find the optimum focal point and then measure from the surface to an edge or feature that is easy to measure.

Complete Answer:

It is easiest to “hunt” for the optimum focal point and then measure the distance from the top surface of the target material to an edge or other feature that is on the focal head. Due to manufacturing processes, it is possible for lenses that are marked as 50.8mm Focal Length to actually perform better at other nearby focal distances. For this reason, a fixed focal measuring device may not be the only solution. Be prepared to simply find the solution that works best for you.

FAQ item was submitted: 5/19/2014 By: Raymond L. Scott

Contact: Raymond L. Scott ... Owner Engineer,, (513) 217-5707

Related Topics: focal distance tool