on 9/18/01 1:07 PM, M. Royer at royer007@xxxxxxxxx wrote:
> the thing with manual mode is that when you shift the
> lens the exposure meter appears to goes off even
> though you have the lens set correctly. You have to
> compose unshifted and get the correct exposure before
> you shift because once the lens is shifted it screws
> things up for the lightmeter because the lens elements
> are no longer lined up straight with the film. the
> interesting thing I've learned is that none of the
> actual glass of the lens moves at all! Just the very
> back end. When I first saw shift lenses I thought
> different elements of the lens moved. I wonder why the
> 24 shift has such a different construction from the
> normal 24mm lens, why couldn't the engineers just glue
> on a 24 normal to a shifting part. Of course I also
> thought the bulging front part was just a thin
> protective filter rather than the front element. Goes
> to show ya how moronic I was just a few months ago :)
>
> Mark Lloyd
>
Lenses actually form circular images. Typically lens designers optimize the
lens design for full brightness and sharpness over an image circle just big
enough to cover the negative area. Hence the typical image circle for a 35mm
lens is about 43.7mm or so. The 24 shift image circle would almost cover a
6x6cm frame... so when you shift the lens, the image is still sharp and
reasonably evenly lighted. That's why the elements are so big, its angular
view from side to side of the image circle is about the same as the 18mm
Zuiko! You can get a pretty good panorama image in two shots just by
shifting full left and then full right the next image. Stitch them together
and you have the horizontal view of the 18mm lens with the vertical of the
24mm. There's a lot of potential for fun with this lens...
--
Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
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