Made for the rainbow imaging MAF lens to NEX adapter, but can be resized if necessary if the diameter is the wrong size.
Sized for 4X6 printing as is. Image can also be reversed and printed on acetate for a more durable scale.(spray with white paint before applying double stick tape and trimming)

Apply double stick tape before trimming.

Cut out index and apply to the center of the lens forward of the aperture ring.
Set the lens to the widest even f/stop and align the scale on the aperture ring to the index.
Some lenses/adapters may not close completely to f/22.