Ed wrote:
> Can someone please explain to me again why magnification and eyepoint are
> not the same? It seems to me, that for any given % (H&V field of view), the
> resulting magnification with a true 50mm lens would pretty much tell you the
> eyepoint would be about the same, right? I know I'm missing something here,
> but since I'm missing it, I don't know what it is I'm missing......
Ed,
Magnification is the relative size of the image in the viewfinder, measured
under certain conditions, usually with a 50mm lens set at infinity or at
some specified distance (I'm sure somebody will correct me about this if I'm
wrong--I actually don't know if magnification has an ANSI standard or if
it's just measured by convention or what). With 1x magnification, the image
in the viewfinder would be as large as the same image seen with the naked
eye.
Eye releif is how far from the eyepiece you can have your eye and still see
the entire viewfinder image. They make "sports finders" which have, in
effect, an eye relief of infinity--you can hold the camera at arms' length
and still see the whole frame, like a leetle tiny TV set. With a finder with
poor eye relief (early screwmount Leicas, as one example) you have to have
your eyeball almost touching the eyepiece before you can see the whole
frame.
One of the ways that manufacturers improve eye relief is by minifying the
viewfinder image--making it lower magnification.
If you ever get the chance, take a Nikon F3 and slide on the original stock
(DE2?) finder. The magnification is high but the eye relief is average. Then
slide on the HP (high-eyepoint) finder. You'll immediately see the
difference. The image is much smaller, but you don't have to hold your eye
close up to the eyepiece to see the whole thing.
One of the great hidden truths about the history of camera design is that
the original Leica M, the M3 of 1953, was designed with a high-magnification
viewfinder for a specific purpose: so you could hold both eyes open while
looking through it. As your eye dominance adjusted, you could actually learn
to see through the thing with normal binocular vision, just as if you
weren't holding a camera up to your eye and looking through glass at all,
but with one crucial difference--you could still see the brightlines. So the
effect was of looking at the world unimpeded except for a white frame
hanging in your field of vision. The closest thing to a camera inside your
head yet invented.
I say this is a "hidden truth" because the need for wide-angle framelines
soon permanently killed the .9x Leica viewfinder, and even Leica, when it
returned to a high-magnfication viewfinder, felt the need to design it so it
could be used with a 35mm lens--and the idiots made it too small for the
"both eyes open" effect that the M3 had provided!! They made it .85x instead
of .9x and the both-eyes-open trick didn't work. I still get a chuckle over
this. The company completely missed _its own_ point.
The ME Super has the closest thing to a life-size finder of any camera I
own; the OM-2n was even a tiny bit better because there was less parallax.
Both cameras with a 50mm lens provide an image about the same size as that
of the naked eye.
Hope this helps. There may be errors in the above, technically, but I think
this will give you the gist of things.
--Mike
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