Gosh folks are mixing up issues! There are two characteristics about viewfinder size:
1. amount of area of the frame of the camera a.k.a. 'viewfinder area', such as 97%
2. magnification presentation thru the eyepiece, e.g. 0.92x.
The Olympus OM-1 showed 97% of the frame, the Nikon F and F4 showed 100%.
The Olympus OM-1 showed the viewfinder at 0.92x magnification (with 50mm lens), the OM-4 showed 0.84x magnification, and the Nikon F4 showed 0.7x magnification.
The reason for the shrinkage in viewfinder magnification (even while showing 100% of the frame area) was the need to cram in all of the camera status displays in the viewfinder area surrounding the focusing screen area!
If manufacturers tried to retain the magnification factor, the pentaprism housing would have grown larger in size to accommodate the larger pentaprism needed to view the 24x36mm focusing screen and the area surrounding it which housed the status displays, increasing cost and price and bulk and weight of the camera.
Last edited by wiltw; 10-23-2011 at 01:02 AM. Click to view previous post history.