P3D Re: Normal lenses and other myths...

[George Gioumousis <georggms@xxxxxxxxxx>]

Dr. George A. Themelis wrote
> 
> I've heard the following method for finding the "normal" FL in an SLR:  Use
> a 35-75 mm zoom, or something similar, and start zooming while looking
> through the viewfinder with one eye while having the other eye open.  When
> the two images match in size, this is the normal FL.  It seems to me that
> this happens when the FL matches some internal distance (from the eyepiece
> to the screen where the image is projected?) built (arbitrarily) into the
> camera.  Is that correct?
> 
I think I've read that an SLR viewfinder has some builtin magnification,
which would give another chance for arbitrariness. My first thought had
been to compare the zoom lens with a pinhole, but that wouldn't work 
either.


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