Hello Olympians,
I had recently the chance to play a little bit with an 35mm/2.8 Zuiko
Shift. I was an near mint lens and the shifting mechanism was very
smooth but firm enoug to hold the lens. The special cross "dovetail"
shifting mechanism allows to make the best use of the existing image
circle. An result is the maximum shift of 13mm down, were all other
shift lenses allow only 11mm.
The amount of shift relativly to the negativ/slide size determins the
relative gain of height you achieve (not the angle of view).
For example: If your negativ has an height of 24mm and you shift the
lens for 12mm, then your relativ gain of height is 50%. This means if
your field of view has an height of 10m then gain 5m (comparable with
the use of an 5m ladder).
Nearly, in fact you have avoided perspectivic distorsions, but you
haven´t changed the perspective (which is determined by your point of
view), that´s why the nomination PC (perspective correction) lens is
incorrect (not PC, ;-) ).
It´s like using an part of an biger, wider angle negative. So the
distortions of the shifted lenses are the same as in the corners of an
respective lens (for the 35mm Shift Zuiko, an 24mm wideangle).
Shifting has some consequences for your view through the finder. Shifted
down, an part of the image rays will be projeced under the mirror,
resulting in an shadow in the finder. Mirror depending metering will be
screwed up to. Olympus is advivceing to meter with unshifted lens.
One realy shocking experiance was, when I was looking through the finder
of an 2-4 screen equiped OM at max shift. There were enormous colored
fringes on contrasty edges.
After the first panic, some herretic thougths about the abilitys of the
Olympus lens designers and some swearing, I did a cross check with an
standard screen of the 1 series and it was much less obvious. So the
1-10 grid screen seems to be the best choise for this lens.
For a further investigation I mounted the camera with lens on an
copystand with a matte screen on the film plane and the shutter fixed on
B.
There were no noticeable color fringes at 4x magnification. But there
was a noticeable fall of image quality in the corner at max shift. It
turned out, that, at least to a part, a curved field of focus was the
reason, which could be confirmed with refocusing.
This is somewhat unconveniant if you consider the intended use of such a
lens. The curved field was not noticeable unshifted, but you´re paying a
lot of bucks for this lens, to use it shifted.
Stoping down to 8-11 helped much to get the whole plane in focus at max
shift.
So much to my preliminary results.
Richard
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