Comments on the Sinar P?

[Bob Salomon]

why do I suspect that Bob won't be answering any of the above... Nevermind, I may as well ask him some more questions which should follow the above...

If the swing point is on the same axis as the tilt point and the lens loses its focus when tilted, is there any possible chance it won't lose focus by exactly the same amount if one swings it for the same angle that he tilted it before?

HINT: The answer is NO-absolutely not! ...focus will be off exactly by the same amount...

Then... if you turn the camera by 90 degs and you swing the lens (so that you now make it tilt) will that make any difference to the focusing?

HINT: The answer is "don't make me laugh"....

Next Q: Then why you insist posting false information like that or all the rest of nonsense bold statements that you have all this time Bob?

It is easier to just gnome you until you learn.

[Theodoros]

No, that happens with any base tilt camera and has nothing to do with the subject yawing on the ground glass which is what will happen with any yaw prone camera if a tilt and swing are used at the same time.

No Bob... It doesn't happen with any camera that has base tilts (or other tilts) it only happens with yaw prone systems because the entrance pupil of the lens is not positioned at exactly the center of the circle of which the tilt arc is part of the perimeter... If the entrance pupil of the lens is positioned at the center of the circle, it will stay constant no matter if the tilt arc is a base one, or any other... You should read what Sinar says on the article that you post better... Is it so difficult for you to understand that the mounting distance is a different thing to the entrance pupil position and that the lens axis rotates only around the entrance pupil... this is basic physics!

Here is some reading for you to help you learn what yaw means in a view camera.

http://www.sinar.ch/en/yaw-free/

It says what I said before Bob... Nothing to do with focus being lost in a yaw free system... It actually says it literally in the first paragraph when describing the yaw prone camera errors that they loose focus: "Focusing turns into a time consuming process of trial and error, until the photographer finally accepts a compromise."

[Theodoros]

Actually to end it... you should read this on the Sinar's statement that you post "... this type of design has the advantage that Scheimpflug´s law is completely satisfied, that is a line through subject, lens and image planes coincides, while a camera which yaws is restricted to a point of intersection of the three planes."

You can't have a line through subject, lens and image plane unless the line passes through the lens entrance pupil (which is a unique point in a lens) now Bob... can you?

[Theodoros]

I mean the lens plane (sorry for the typo on the post before) is always a plane that includes the entrance pupil of the lens as one of the plane's points... And it is always perpendicular to the lens axis (that is also passing through the entrance pupil)... no? And the entrance pupil is the point in the lens that is focused... no? So, if a camera looses focus if tilts (or swings) are applied, it means that it is yaw prone... So the mounting board has nothing to do with a camera being yaw free... The tilt mechanism of a camera that claims to have been designed for yaw free operation, has a center around which it rotates... So the lens entrance pupil must be positioned exactly on that center...

And of course cameras that rotate by 90 degs and (by some voodoo magic) become yaw free... are pure nonsense "theories", created by people that are complete ignorants on the matter...