On Mon, Jan 28, 2002 at 10:09:18AM -0800, William Sommerwerck wrote:
> Olympus claims their new lens design gets around this problem by moving the
> exit node farther from the film plane, thus making the angle of attack less
> acute. This doesn't sound right -- the angle at which the light rays strike
> the
> film is, by simple geometry, unavoidably linked to the lens's angle of view.
> How can you make the angle less-acute without simultaneously reducing the
> angle
> of coverage?
This is possible with retrofoocus lens design. This is used for SLR-wide
angel-lenses.
Without this trick it woudn`t be possible to place the mirror between the film
and lens
with focal lenghts shorter than 35mm.
Frieder Faig
>
> So I did some research. In every reference I checked, a lens's focal length is
> _defined_ as the distance from the exit node to the film plane. In other
> words,
> you can't change the position of the node without simultaneously changing the
> lens's focal length. QED -- Olympus's claim is not kosher.
This is a simplification which is suficcent for working in the field...
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