We had a very interesting and intensive thread about the stitched panos and
lens entrance pupil measured from the film plane in 2003, taking in mind
it's the point to rotate the lens-camera combo to avoid parallax and
mismatches to stitch the frames; this is a significant issue even if you
use a pano software.
Emmanuel Bigler calculated that the entrance pupil for the SL66 Planar
2,8/80 was 90 mm from the film plane during that discussion and Siu Fai Au
checked out with this camera and this lens he was right.
It happens the standard lens for my Sl66 is the Distagon 4/80 with an
additional Compur leaf shutter, the lens construction is different
regarding the Planar completely. A first inspection watching the f stop
image through the front of the lens showed a "virtual" image beyond the
physical diaphragm coinciding -more or less- with the Compur sutter speeds
ring,closer to the lens external surface than the f stops ring, the
distance from the flm plane was about 125mm. I put the tripod platform or
"tripod head" I designed to measure the TLR entrance pupil in 2003 and
built by a friend of mine on a tripod with the SL66 and lens. I took some
suitable subjects as reference and perceived the parallax disappeared
according I advanced the camera-lens combo from 90mm to 120mm, on 120mm
from the film plane the paralllax was imperceptible, but it was also the
limit for my device to change the rotation axis, perhaps the exact point
for the entrance pupil could be 125 to 130mm from the film plane; anyway I
think 120mm will be enough for practical purposes, I'll see taking
photographs in the future.-
Most called "pano heads" for pro tripods hardly can change the camera-lens
combo rotation axis, it´s fine for several reflex digital cameras and 35mm
film cameras with standard lenses, including the TLR too, but a big camera
like the SL66 needs dedicated pano heads with rules to measure the entrance
pupil and capability to vary the rotation axis widely. I thought my device
for the TLR, but I think it will help with the SL66 up to some point; you
can see it here:
http://dobleobjetivo.blogspot.com/2007/06/rollei-panorama-head-rotation-axis-test.html
Carlos
