The commonly reported reason for less than 100% coverage is to compensate for cropping due to mounting a transparency in a slide-mount.
I do not find this very convincing. Tolerance in manufacture may be another reason.
This is true I had a Nikon F2 and was shooting slides exclusively with it and was losing a significant amount of the image area after mounting, and this also applies to enlarger negative carriers if you don't file them out to accommodate the full negative area. I find the ideal viewfinder coverage for film is that of my Canon New F1's which is 97%
The reason for why not 100% and 1x in the finder is simple, you have to give up eyepoint to achieve that, making it difficult to actually see the entire field of view (and for some, actually painful). Both the OM-1n and the Pentax MX (which actually has the highest finder magnification) have major issues for eyeglass wearers due to the very low eyepoint, and personally I find the MX literally painful to shoot (major eyestrain issues). The best all-round finders are either the 100% ~0.8x finders in cameras like the F2 or non-HP F3 or for eyeglass wearers the high-eyepoint finders in the F3HP, F4 and F5.
Ralph, our eye vision is essentially ultra-wide. My peripheral vision used to be significantly greater than 180 degrees (now it's less) but that's just the way my eyeballs see, not the way my brain sees. Our human brains concentrate our attention on primarily the center few degrees of what our eyes see... almost like having long lenses rather than wide. However, we move our eyes in all directions and our brains "piece together" a fuller view of our surroundings. It's a far more complicated process than I care to study about.
I'd say, for most folks, the age-old way of calculating lens normal focal length works fairly well. For me, I think I see wider than that but I do tend to look around a bit more than most folks so maybe that's why. I also tend to prefer wider horizontal images at 1:2 or 1:2.5 ratios moreso than other formats perhaps because in the real world I find it easier to turn my head right/left and move my eyes horizontally rather than move my head up/down and move my eyes vertically. So I guess I have a less tall and wider view of the world.
At any rate, our "vision" is more of a brain thing than the actual view seen by our eyeballs.
Last edited by Old-N-Feeble; 11-27-2014 at 09:52 AM. Click to view previous post history.
Was not the 35mm film frame of the day 24mm by X mm wide since it went through the ‘movie’ film gate in a different direction. The ‘diagonal’ of the frame is now ‘smaller’ that what we get with a 36 x 24mm image area and should we now ‘disregard’ that aspect ratio as a function of ‘normal’ field of view?
Cost is the big driver 6x6 cameras have similar focal length rule sets, 6x7, 6x9, etc.
Technology has improved optical glass with
refractive index 1.9, wide range of dispersions
high refractive index glass fluid at very low melting temperatures, high precision ceramic molds
Only a few design innovations, (like Konicas 40mm Pancake patent)
Ive no problems with OM1s with the x0.9 finder magnification eye relief and eye glasses, in dim light I need to wind the variable dioptre of OM4s to one extreme to use matt/micro focusing, with my current spec prescription.
Nikon F and F2 were expensive for the additional tolerances needed (and materials for motor drive use).