On 01/10/2015 20:05, NY wrote:
"dennis@home" wrote in message
web.com...
On 01/10/2015 14:28, NY wrote:


The only time when the precise position of the tripod mount is
critical (as
far as I am aware) is when taking multiple overlapping photos eg for a
panorama. I have seen special brackets with knurled knobs to move the
rotation point accurately to the position of the sensor if the
camera's own
tripod bush isn't in the right place, though I'm not sure how you
calibrate
it. It is probably important for movie cameras where the geometry has to
remain correct when panning during filming so a subject moving on a
circular path centred on the rotation point will remain in focus.

The place that you need to pivot around isn't the film plane.
There is a node inside all lenses where rotating about that point
doesn't change the perspective as the image moves across which it will
do if you rotate the camera around the film plane.

http://www.panohelp.com/panoramicpivotpoint.html

Ah, OK. My mistake for mentioning what's turned out to be a total red
herring :-(

There are always new things to learn.
At least you want to learn unlike some.


It seems that manufacturers positioning the tripod point roughly where
the sensor/film is coincidence and that rotating about that point
doesn't make much sense for panoramas or for movie work where you don't
want perspective changes as the camera pans.

Its quite difficult to grasp the concept without proper explanations and
a few drawings. I wouldn't expect the average photographer to even know
about it. I would expect cine camera operators to know.

I hate to think what the next generation of photographers "know".