Comments on the Sinar P?

[Theodoros]

Theoretically 100% correct. But just mounting your lenses on plain old Sinar lens boards will work most of the time for most of your shots as long as your movements are not extreme. Have done it this way with Sinars since the 1980s. Willing to bet most of Sinar P users simply do it this way. Few years ago reverted back to Sinar Norma systems (4x5 & 8x10). Bit more compact and personally more of a pleasure to use in the field.

Hi Greg, yes this is correct... In fact I mentioned it in my very first post in this discussion if you look back... the yaw error with the P system will be less, this is because the tilt's arc radius is a huge 120mm (much larger than other cameras) which results on the error to decrease with respect... Additionally all shift mechanisms are bellow the swing/tilt ones, which means that when one shifts, he doesn't influence the tilt or swing geometry at all... However, making the camera completely yaw free (which only requires some simple knowledge and some -again simple- self involvement) will be of much benefit... Especially if one works with smaller image areas and at closer distances.

[Theodoros]

I thought you said that you were an astronaught. If so, then you know Bob Cabana. Google him and learn. I taught him, and his fellow crew members, how to use the Rollei 6008 on the Space Shuttle. Also how to use the Linhof Aero Technika 45 EL on those missions as well.

I'm an astronaught (that has traveled all over galaxy in secret missions), as much as cameras become yaw free if the swing point is positioned above the tilt point or if they are side turned by 90 degrees so that their tilt mechanism becomes swing and the swing acts as tilt...

There is no way for this invention (or other) to apply, unless if the entrance pupil of the lens is positioned exactly at the center of the tilt arc and the axis that is formed by aligning the entrance pupil of the lens and the swing point, intersects the tilt arc at its "0" position...

Additionally, the only way for a camera to retain its yaw free operation and shifts are applied, is if when side shifting, one side shifts the swing point along with the entrance pupil of the lens and if he uses up-down shifts he ups or downs the tilt mechanism along with the entrance pupil of the lens (that's why shift mechanisms MUST be bellow the respective tilt and swing ones)... All other "theories" are just alchemist inventions that lead to into inducing distortions on the image....

[Bob Salomon]

I'm an astronaught (that has traveled all over galaxy in secret missions), as much as cameras become yaw free if the swing point is positioned above the tilt point or if they are side turned by 90 degrees so that their tilt mechanism becomes swing and the swing acts as tilt...

There is no way for this invention (or other) to apply, unless if the entrance pupil of the lens is positioned exactly at the center of the tilt arc and the axis that is formed by aligning the entrance pupil of the lens and the swing point, intersects the tilt arc at its "0" position...

Additionally, the only way for a camera to retain its yaw free operation and shifts are applied, is if when side shifting, one side shifts the swing point along with the entrance pupil of the lens and if he uses up-down shifts he ups or downs the tilt mechanism along with the entrance pupil of the lens (that's why shift mechanisms MUST be bellow the respective tilt and swing ones)... All other "theories" are just alchemist inventions that lead to into inducing distortions on the image....

In plain simple English, explain what you believe yaw means in a photographic application. Hint, it has nothing to due with the entrance or exit pupil of the lens, it has all to do with the mechanical movements of the camera.

[Theodoros]

In plain simple English, explain what you believe yaw means in a photographic application. Hint, it has nothing to due with the entrance or exit pupil of the lens, it has all to do with the mechanical movements of the camera.

Ιn plain English, your hints are that make me an astonaught that has travelled all over galaxy in secret missions... Open a book on optical theory just to verify that lenses don't rotate on their axis unless the rotation is performed with their entrance pupil being firmly locked in the same (unique) point... This is because a sphere has ONLY ONE center...

EDIT: In return let me give you a hint... lenses project cones on the light sensitive area surface... and cones are parts of a sphere of which the base is intercepted VERTICALLY and that base is always at 90 degs with respect to the radius of the sphere... In other words if your lens entrance pupil moves (at a different position from the center of the sphere), you won't get a circle projected, but an "egg shape" instead.... In other words, if the axis that passes through the entrance pupil of the (repositioned) lens and then through the center of your image area is not exactly perpendicular to the image area but angled, ...the shape of the projection will be distorted from circle to egg-shape...

[Bob Salomon]

Ιn plain English, your hints are that make me an astonaught that has travelled all over galaxy in secret missions... Open a book on optical theory just to verify that lenses don't rotate on their axis unless the rotation is performed with their entrance pupil being firmly locked in the same (unique) point... This is because a sphere has ONLY ONE center...

EDIT: In return let me give you a hint... lenses project cones on the light sensitive area surface... and cones are parts of a sphere of which the base is intercepted VERTICALLY and that base is always at 90 degs with respect to the radius of the sphere... In other words if your lens entrance pupil moves (at a different position from the center of the sphere), you won't get a circle projected, but an "egg shape" instead....

So you do not know the definition and cause of photographic yaw!

[Drew Wiley]

Gosh, Bob, everybody knows Sinar came out with the first popular patents for yaw-free operation and first aggressively marketed the concept, and that the P series was an outright home run for studio use, and still is. I can think of certain standardized studio setups where yaw-free operation is a distinct convenience.
But my personal favorite Sinar is the Norma, which predates their venture into yaw-free. I never paid much attention to that yaw-free feature when I did own the relevant Sinar models. Otherwise, nothing gets thrown out. It's a fully interchangeable system. My P standards ended up as part of the focus mechanism on a big custom enlarger. It's an awfully heavy and bulky camera for field use, which is my main interest. The Norma is just right.

[Bob Salomon]

Gosh, Bob, everybody knows Sinar came out with the first popular patents for yaw-free operation and first aggressively marketed the concept, and that the P series was an outright home run for studio use, and still is. I can think of certain standardized studio setups where yaw-free operation is a distinct convenience.
But my personal favorite Sinar is the Norma, which predates their venture into yaw-free. I never paid much attention to that yaw-free feature when I did own the relevant Sinar models. Otherwise, nothing gets thrown out. It's a fully interchangeable system. My P standards ended up as part of the focus mechanism on a big custom enlarger. It's an awfully heavy and bulky camera for field use, which is my main interest. The Norma is just right.

The patent was not for yaw free. It was for asymmetrical axis movements. Linhof was sued by Sinar over the Kardan Master L camera that had continuously variable asymmetrical movements and Linhof lost that suit and had to pull the L off the market because one of those continuously asymmetrical points on the Linhof was the same point that Sinar used on the P.
Again, Linhof showed the first yaw free camera, the original Kardan, many years before Sinar ever introduced the P series.

[Theodoros]

Drew, Sinar was the first that did describe yaw free as being able to have "the swing axis on the tilt plane when both movements are combined", but they "forgot" to mention that the tilt plane IS NOT the lens board plane unless one makes sure that the entrance pupil of the lens is positioned on the lens board... Further more, on the P series, both the swing plane and the tilt plane are positioned on a parallel plane to the plane that the mechanisms apply...

The truth is that if the swing axis is on the tilt plane, this is not enough for the system to be yaw free, but the swing axis and the tilt axis must cross on the point that the entrance pupil of the lens coincides on... Otherwise one will see all plane lines as being parallel (which is a major factor for yaw free operation but not the only one) but there will be geometrical distortions that will remain on the image plane itself (proportions of dimensions will be altered from left to right and top to bottom on the image plane) not by much on the P system (because tilt arcs radius is a huge 12cm one)... but the distortions across the image plane will not be corrected.

Now as for bulk, this is a personal matter... Certainly the camera is not aimed for one to carry it around and play Ansel Adams with it shooting landscapes... (after all who cares for accuracy or distortion with distant subjects?). It is aimed for one to work on a tripod for professional studio work or serious architectural interiors, or other photography that requires the maximum of accuracy and skills as to get the maximum out of it... The Norma is no where near the P series for this kind of work, so its a (personal) matter on photographic priorities....

[Theodoros]

The patent was not for yaw free. It was for asymmetrical axis movements. Linhof was sued by Sinar over the Kardan Master L camera that had continuously variable asymmetrical movements and Linhof lost that suit and had to pull the L off the market because one of those continuously asymmetrical points on the Linhof was the same point that Sinar used on the P.
Again, Linhof showed the first yaw free camera, the original Kardan, many years before Sinar ever introduced the P series.

Gosh Bob! You can't patent YAW FREE operation of a camera because no camera by itself can ensure that the result will be yaw free... YAW FREE is a lens positioning matter with respect to the image area, a camera will work different with different lenses depending on each individual lens entrance pupil position...

Most makers of cameras claim "yaw free" operation these days... and guess what... All of them "forget" to add the phrase: "only with symmetrical lenses", All of them "forget" to mention that the tilt plain and swing plane must cross on the axis that also crosses the entrance pupil of the lens and 90% of the makers (Linhof included - Sinar excluded on the 90%) forget to mention that if your side shift mechanism is above your swing or the up-down shift above your tilt and you combine the movements... you can "kiss yaw free operation goodbye" even if the entrance pupil is positioned correctly... give us a brake will you? ...and please stop posting nonsense like cameras becoming "yaw free" if their swing is above tilt or "all cameras becoming yaw free if they are turned 90 degrees to the side" (especially since you never have backed up with some theory as to support those nonsense)....

We are not all as ignorants as some of your customers might have been in the past as to invent sale properties of cameras that do not exist...

[Drew Wiley]

Theodoros - "yaw free" is irrelevant in most architectural work because the camera is typically leveled first, before tilts, swings, or rise. It's logical application is production tabletop studio photography. I'll let you and Bob argue the finer points of the subject. Sinar made a big fuss about buying perfectly nodal-centered mounted lenses from them, at a premium of course. Symmetrical, assymetrical, whatever; I just do it based on rote familiarity with each particular style of camera, having forgotten the theory long ago. But to suggest that there is anything less precise about outdoor photography is utter ballyhoo. And there is certainly
more demand on equipment reliability. Try getting a little sand in that P gearing.