Optional Nikon eyepiece dioptre allows you to
optimize your SLRs viewfinders' sharpness in conjunction with your eyesight.
Eyepiece dioptre are designed for specific cameras model and are identified by a
plus a minus or a neutral numeric dioptre value.
Standard eyepieces supplied with Nikon SLR cameras have no corrective value and
are for dust protection only.
Nikon SLR cameras (without built-in adjustable eyepiece correction) have a base
dioptre value of minus one. This is why you won't find an accessory Nikon
eyepiece dioptre valued at minus one. Minus one is considered the optimum
starting point for the majority of SLR users with standard vision.
For D300, D200, D100, D90, D80, D70, D60, D50, D40, N80, N75, N70, N65, N60,
N55, N50, Pronea, N2-4-5-6000 Series & FM/FE10 Cameras
For more information about, Nikon Diopter +1.0 For F & D Series SLR Cameras .