On Sun, Apr 21, 2002 at 10:39:55PM +0200,
frieder.faig@xxxxxxxxxxxxxxxxxxxxxxxxx wrote:
> On Thu, Apr 18, 2002 at 09:40:39AM -0700, Dave Shupe wrote:
> > I am nearsighted (-2.0) with a slight astigmatism. I've noticed lately that
> > I can focus my binoculars at any distance, and see sharply without my
> > glasses. My question is, why can't I focus the camera the same way.
> >
> > I understand why it would not be good to do so, kind of like handing the
> > binoculars to someone with good vision, they have to refocus. Therefore If
> > I could focus without glasses my pictures would be blurry. Just wondering
> > how the camera focus system actually works.
>
> This is my idea to this topic:
> The mate-part of the focusing screen forces your eye to focus
> the picture of the lens on the level of the film plane. With your
> binoculars it doesn`t matter in which plane you can see the image.
> Because of that there is no need for a mate-sreen in the ray path
> of a field glass. One focusing mechanism is sufficient to compensate
> for distance and eysight differences.
>
> With a clear screen (1-5; 1-6; 1-7) your eye can see a sharp image
> of your subject which is not in the propper distance. I guess this is
> why you can only focus with the microprism area when using this screens.
>
Oops:
There is a orthograpy error: "matte" is missing one t in my text above. I´m
refering to the
"matte-area" of a focusing screen and not about friends or chess, or ...
Frieder Faig
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