At 10:38 AM 12/2/01 +0000, you wrote:
>At 15:05 12/2/01, Alan asked:
>
>>What exactly are the advantages of a shift lens vs shift/tilt lens? The
>>zuiko 24 shift is suppose to be very good. The canon is suppose to be
>>reasonable (but all reports I've read indicate it is optically inferior
>>to the zuiko). On the other hand it also supports a tilt mechanism
>>(which I think the zuiko lacks).
>>
>>Alan
>
>The tilt allows variation of the critical focus distance across the film
>plane. A traditional landscape with very, very close foreground and very,
>very distant background is a classic example for using it. By tilting the
>lens down (or by tilting the back up; it's all relative), the bottom part
>of the image will have a closer critical focus distance than the upper part
>of the image.
>
>Nearly all primes are focused at some distance closer than infinity by
>moving the lens farther from the film plane. Remember that images are
>inverted and reversed on the film in the camera(top of image is on bottom
>of film in camera, and left/right are reversed). The greater the tilt, the
>greater the difference.
>
>This is one of the things a large format technical view camera can do that
>almost none of the MF and 35mm small format systems can. AFIK, Can*n's
>tilt lenses are the only ones that allow this in 35mm work.
>
>-- John
Several people have pointed out that a superwide and Panorama Tools (or similar)
can be used like a shift in many circumstances. (Such as outdoor shots where
you have lots of DOF.) Another thing they can do is convert a shift-only
lens to a tilt-shift.
Consider shooting a tabletop shot. You tilt the lens down to make the zone in
focus lie more parallel to the table, then adjust the back tilt for keystoning
correction. With a shift, you can shift up, then point the axis of the camera
body down so that the back (and the lens) lies more parallel to the table.
This is largely equivalent to a tilt. Then you could use Panorama Tools to
undo the resulting (reversed) keystoning. PT can change lens projection, but
not where the focus was; so use your camera and lens for that. I've tried it;
it works. But since I don't have Photoshop, I can't do the keystone correction
yet, so I only get the tilt effect.
Paul Farrar
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