Question: how many cm in 1 diopter?
Answer: For example, suppose an object is at 1/2 meter. Converted to centimeters, the object is 50 cm away. Divide 100 by 50 and the result is 2 D of power needed to focus at this distance. The formula to remember is D = 100/F, where D is diopters and F is the focal length (or distance) in centimeters.