Schneider 138mm Diopter Kit

Set of four Schneider 138mm full diopters for reducing the minimum focus distance of a lens: +1/2, +1, +2 and +3.

To roughly calculate the minimum focal distance when used with a diopter you can use the following formula:

MFD / (MFD * D + 1)

MFD = Minimum focal distance (in meters) D = Diopter Strength

This formula will only give you an approximate value.