http://www.nikonchat.com/nikon-dx-vs-fx/

Viewfinder size fullframe not against fullframe (increases)?
The size of the display are: Nikon D3: 100% increases in PV with Nikon 0.7x D700: 95% GF with magnification 0.72 x Canon 5D: 96% PV 1DSMKII Canon 0.71x magnification: 100% 1DSMKIII Canon 0.7x increase: 100% PV 0.76x magnification Only reading this I wondered … DX 0.76 A increase is 50% smaller than a 0.76 FX with the same expansion of the D3 is really 0.7 increases with a camera Old Pentax film and holds 0.95 of the increase, which is larger than the D3?
Hi Phil, the apparent size of the viewfinder image can be calculated by multiplying the film or image sensor area by increasing the coverage viewfinder and display. You do not say what the film SLR Pentax had, but only two of them the 95% increase in the viewfinder. These two were the MX and K2. I assume yours is the MX. The Pentax MX was 0.97 viewfinder magnification. So it's viewfinder image size is apparent: Pentax MX Film SLR: (24 mm x 36 mm) x 0.97 x 0.95 = (22.1mm x 33.2mm) Compare that to the Nikon D3: (24 mm x 36 mm) x 1 x 0 , 7 = (16.8mm x 25.2mm) So yes, the MX Pentax film SLR has a larger viewfinder image apparent size as the Nikon D3. If you add the Nikon DK-17M magnifying Eye of the D3, which magnifies the image of the Nikon D3-17M 1.2x to 1.2 x eyepiece magnification DK: (24 mm x 36 mm) x 1 x 0.7 x 1.2 = (20.2mm x 30.2mm) Here is the 1.2 X-17M magnifying eyepiece DK http://www.bhphotovideo.com/c/ search? Ntt = dk-17m and N = 0 & InitialSearch = yes Good luck and have fun! Greg
DX/FX Crop Factor Explanation