A couple of years ago I picked up this old Nikon 200mm f/4 lens from the early 70s for $35 and the Nikon 4T closeup lens for about $50. The 4T is 2.9 diopter. This combo allows a reproduction ratio of almost 1:1 with the lens set at it's minimum focus distance. What is 1:1-it's lifesize. My sensor on ny DSLRs are 24mm across from left to right. That means if you took a pic of a ruler at 1:1 you would get 24mm of the ruler in the frame. But if you get the non or pre AI version of this lens just make sure you have a Nikon body that will safely accept pre AI lens. Mine has been AI modified.