The Mamiya Farsighted Diopter adjusts the focus of the camera’s viewfinder in order to match with the eye sight of the user.This Mamiya 645 AF camera body comes with a built-in diopter, ranging from -2.5 to +.5Optional medium format diopters (standard and far sighted) can also be used with the camera body to make fine dioptric adjustmentsThis farsighted range diopter can be adjusted from 0 to +3