Viewfinders have two three important statistics:
Amongst Nikon film and FX digital SLRs, the FM2N is one of the better cameras for manual focusing due to the high magnification of the viewfinder image of .86%. Compared with this, the magnification in the D3 is .70%, whereas the F6 magnification is .74%. Nikon sells viewfinder magnification accessories that increase the viewfinder magnification, while reducing the eyepoint. The DK-17M adapter increases magnification by 1.2x and can be used in the F6/D2/D3 series cameras. The DK-21M is meant for the prosumer DX SLRs.
Nikon, and all other vendors, cheat when they report the viewfinder magnification of APS-C format DSLRs. A 0.94x magnification for the D300 sounds good until you realize that this is in terms of a 50mm lens, which is actually equivalent to a 75mm lens on the full frame cameras. To get a real sense of the viewfinder magnification of an APS-C camera, you need to know the magnification when using a 33mm lens, but no manufacturer will tell you that. Some people assume that to get the APS-C equivalent magnification, you just need to divide 0.94x by 1.5, giving you 0.63x, but I am not convinced that this is the right formula. Visual comparison tells me that the D300 has close to effective magnification of .75% when using a 35mm lens. I asked Nikon Support for the formula to work out the magnification but they were not able to (or not willing to) provide me one.
|Camera||Viewfinder magnification using 50mm at infinity||Viewfinder Coverage||Eyepoint|