Why are asymmetric movements asymmetric?

[bieber]

I understand how to use asymmetric movements. I think I understand how they work as well: when you tilt or shift the rear standard, it's arranged such that the axis of the tilt/shift passes through the ground glass right along the marked lines. That means that line along the ground glass remains stationary, so of course its focus won't change as the distance to the lens of that particular slice of the image doesn't change.

What I don't quite understand, though, is why it's necessary for these axes to be offset towards the edges of the image. With a camera that tilts/shifts around the center of the film plane, couldn't you simply line your subject up along a center line and then repeat the same procedure you use on a camera with asymmetric movements? Are the offset axes just there because it's usually more convenient for composition purposes to use an object closer to the edges of the frame?

[Bob Salomon]

I understand how to use asymmetric movements. I think I understand how they work as well: when you tilt or shift the rear standard, it's arranged such that the axis of the tilt/shift passes through the ground glass right along the marked lines. That means that line along the ground glass remains stationary, so of course its focus won't change as the distance to the lens of that particular slice of the image doesn't change.

What I don't quite understand, though, is why it's necessary for these axes to be offset towards the edges of the image. With a camera that tilts/shifts around the center of the film plane, couldn't you simply line your subject up along a center line and then repeat the same procedure you use on a camera with asymmetric movements? Are the offset axes just there because it's usually more convenient for composition purposes to use an object closer to the edges of the frame?

They don’t have to be there, that is where Sinar wanted the line to be.
Linhof used a continuously variable asymmetrical system that allows the user to place the line where ever they needed it to be.

[Peter De Smidt]

Sinar uses two point focusing/tilting/swinging. You don't specify a plane with just one line.

[Bernice Loui]

Which is easy to use, accurate enough and fast to set tilt / swing. This was the time saver that made Sinar THE most popular studio camera, specially for table top work. First Sinar to offer this feature was the original Sinar P. The idea was good enough and effective enough for Linhof to do a version of it, which resulted in Sinar Legal action against Linhof. This resulted in other view camera makers trying to figure a way around the Sinar Patent until the Patent expired....

From January Pop Foto, 1988:
183824


Bernice




Sinar uses two point focusing/tilting/swinging. You don't specify a plane with just one line.

[Bob Salomon]

Which is easy to use, accurate enough and fast to set tilt / swing. This was the time saver that made Sinar THE most popular studio camera, specially for table top work. First Sinar to offer this feature was the original Sinar P. The idea was good enough and effective enough for Linhof to do a version of it, which resulted in Sinar Legal action against Linhof. This resulted in other view camera makers trying to figure a way around the Sinar Patent until the Patent expired....

From January Pop Foto, 1988:
183824

Sinar sued Linhof for the asymmetric movement in a German court and the court ruled in Sinar’s favor as the continuously variable points that Linhof used infringed on the non variable point that Sinar had patented.

That is all that it was about. It had nothing to do with yaw free movement which Linhof introduced, but never used, on the original Kardan prototype and which was used on a very early French camera.
Bernice

[Doremus Scudder]

To answer your question in a bit more detail.

In essence, adjusting the plane of focus with center axis tilts/swings is exactly like using asymmetrical tilts/swings except that the distance between your two focus points (the one you set on the tilt/swing axis and the one you tilt/swing to get into focus) is greater with asymmetrical tilts/swings. This has the advantage of being inherently more accurate due to the larger focus distance between the two points. Whether this makes a lot of difference in practice depends on your focusing technique, eyesight and loupe.

Anytime you focus using a tilt/swing axis, you are constrained to choosing a focus point that lies somewhere on the axis line. That isn't always practical. In that case, I simply choose off-axis focus points and focus using the focus-tilt/swing-refocus-repeat till all is acceptably sharp method (the same as is required if you use base tilts, by the way). I'm fast enough with either method that I never really feel the need for asymmetrical tilts/swings.

Best,

Doremus

[Drew Wiley]

Sinar actually patented two different asymmetric methods, one for the P and X series, the other for the F series. Eventually, of course, the patents expired and certain things got copied. Being able to correct for yaw is useful if you are trying to simultaneously use both tilt and swing when the camera if pointed downwards, like in studio tabletop setups. Otherwise, even as a long-time Sinar user, I ignore it. In fact, my favorite Sinar is the Norma, which doesn't even have this feature. But I mostly shoot things like landscape, nature closeups, and architecture. By contrast, I have a friend that does food photography in a highly-equipped studio/kitchen, and in that case the yaw-free feature is a real time-saver. Time is important in today's high production studio environments with almost instant digital conversion to pre-press, and if you want the food to still be warm long enough to eat it! - one of the perks of working with world-class chefs in your own studio!

[Bernice Loui]

There was a time when commercial studios would produce vast quantities of 4x5 color transparencies for catalogs and sales brochures. Projects like this are often done as table top, controlled lighting using hundreds if not thousands sheets of 4x5 color transparency film. Ease of camera use, high quality images and minimal waste is very important as time = $. This is where Sinar P made it's name. For combined camera movements, the Sinar P just got it done. Adding to image making efficient is the Sinar shutter system with aperture stop down (Sinar DB lenses) once the film holder is loaded from a pre-set value and aperture returning to full once the film holder is removed. The shutter being self winding or electronic added to the overall efficiency. Exposure control via the Sinar metering probe with metering back help reduce film waste and improved exposure accuracy. If specialty lens shading is needed, most any configuration can be made up. Color correction filters can be easily added to achieve proper color balance with a given color transparency film and lighting. What Sinar created was a highly integrated, precise, integrated image making system, with very few camera system limitations with no real equal for this kind of work.

Much of this does not apply to the outdoor view camera used who does hiking and travels to remote places to create images. Camera requirements and needs are very different in most every way.


Bernice

[Ken Lee]

Are the offset axes just there because it's usually more convenient for composition purposes ?

Definitely.

Further to Bernice's and Drew's points, it's very convenient when you want to combine movements. There is no need to struggle through an endless cycle of adjustments and re-adjustments. You just dial them in, in whatever order you like.

By way of example, you might find this article helpful: View Camera Movements (http://www.kennethleegallery.com/html/tech/ViewCameraMovements.php).

Note the first image and the last two images, which utilized several adjustments at once. They were trivial with a Sinar P.

Not having to worry about maintaining focus, you can concentrate on aesthetics and play with the plane of focus, rather than have it play with you.