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el french
14-Jan-2009, 00:34
Can someone explain asymmetric movements and why they're better?

Eric Leppanen
14-Jan-2009, 00:54
http://www.ebonycamera.com/media/asymmetrical.movements.pdf

aphexafx
14-Jan-2009, 02:21
Great read.

Joanna Carter
14-Jan-2009, 03:13
We currently have an interesting discussion on assymetric movements, in the UKLFPG forum : http://www.lf-photo.org.uk/forum/viewtopic.php?t=819

Vlad Soare
14-Jan-2009, 05:40
http://www.ebonycamera.com/media/asy....movements.pdf
Nice article, but it doesn't quite explain why asymmetrical movements are better, or more convenient, than symmetrical ones. I'm reading it more like "why asymmetrical movements are better than no movements at all" (especially those two examples).

With asymmetrical movements, you pick a part of the subject plane that falls on the dashed line (the tilt or swing axis, that is). Then you use this point as a pivot - focus on it and start tilting, and it will stay focused while the other parts of the subject come in focus, too.
With symmetrical movements, you pick a part of the subject plane that happens to fall in the center of the frame. Then you use this point as a pivot.
So, where's the difference? Why is an off-axis pivot better, or more convenient?

I'd understand the convenience if you could pick a tilt/swing axis of your choice (I mean, place the tilt/swing axis wherever you want). But, if I understand correctly, the tilt/swing axis is still fixed, only moved a little sideways. Am I missing something? :confused:

David A. Goldfarb
14-Jan-2009, 06:05
I'd understand the convenience if you could pick a tilt/swing axis of your choice (I mean, place the tilt/swing axis wherever you want). But, if I understand correctly, the tilt/swing axis is still fixed, only moved a little sideways. Am I missing something? :confused:

Depends on the camera. With a Linhof Master GTL, you can move the tilt and swing axes.

With a Sinar P or P2 what you can do if the axis isn't in a convenient place is use the rear rise/fall/shift movements to put the axis where you want it and measure the tilt/swing angle on the rear standard using the protractor scales, then you can leave the movement on the rear standard and return the rise and shift movements to the original composition, or transfer the tilt/swing to the front standard using the front standard scale and return the rear standard to the neutral position, and return to the original composition with the rear rise/fall/shift movements, and in either case the tilt/swing angle will not change. It sounds more complicated than it is, and once you get the hang of it, it's pretty quick to find tilt and swing angles this way.

Vlad Soare
14-Jan-2009, 06:21
I see. That makes sense.
But then, you can do the same with "normal" (symmetrical) axis tilts/swings. No need for asymmetrical movements. :)

As I see it, if you have asymmetrical movements and find a convenient pivot on the dashed line, great. If you have central axis movements and find a convenient pivot in the center of the frame, great. Otherwise it doesn't really matter which kind of movements you have, because you're going to be refocusing (or moving the tilt/swing axis by shifting the standard, like you say) anyway. Is this correct?

Joanna Carter
14-Jan-2009, 06:36
I see. That makes sense.
But then, you can do the same with "normal" (symmetrical) axis tilts/swings. No need for asymmetrical movements. :)
My point exactly! I just can't see why you "need" asymmetric movements, which is the reason why I started the discussion in the UK forums.

Frank Petronio
14-Jan-2009, 07:07
They're mainly a nice marketing ploy to sell more complex and expensive cameras to hobby photographers who want to buy "status symbol" cameras. Considering that 95% of the customer base for these cameras only does one kind of simple landscape photo with a little front tilt and maybe some rise/fall/shift, it's overkill.

Back "in the day" having asymmetrical movements was an advantage in mass-production studio catalog tabletop photography, where a camera might actually run into a problem with tilt and swing creating a unresolvable yaw situation -- shooting down onto a bottle and wanting to keep the bottle vertical and catch focus across a diagonal plane. But it was only unresolvable until the photographer stopped the lens down a couple of extra stops.

Joanna Carter
14-Jan-2009, 07:27
Back "in the day" having asymmetrical movements was an advantage in mass-production studio catalog tabletop photography, where a camera might actually run into a problem with tilt and swing creating a unresolvable yaw situation ...
So, Frank, a couple of questions :

What effect does yaw have on the image?

Or does yaw just make it more difficult to achieve desired movements?

Would an Ebony SV45Te be considered as yaw-free or yaw-prone?

David A. Goldfarb
14-Jan-2009, 07:35
As I see it, if you have asymmetrical movements and find a convenient pivot on the dashed line, great. If you have central axis movements and find a convenient pivot in the center of the frame, great. Otherwise it doesn't really matter which kind of movements you have, because you're going to be refocusing (or moving the tilt/swing axis by shifting the standard, like you say) anyway. Is this correct?

Depends on the camera as well. A Sinar P/P2 is designed so that you can find the tilt or swing angle without having to refocus and repeat, because the rear tilt/swing axes are really aligned with the focal plane, so you can see what's in focus as you tilt on the groundglass as you tilt, without having to guess, refocus, try again, etc. Then there are levels and scales on the camera so that after you've found the tilt angle on the rear standard, you can decide whether to keep the rear tilt or apply the same movement to the front standard.

Not all cameras have rear axis tilts, and if you have rear base tilt, the tilt axis is often below the frame. If you have rear axis tilts, with the tilt axis in the center of the frame and aligned with the focal plane, and you have a convenient way of measuring the tilt angle on the rear standard and applying it to the front standard, then you can use it like a Sinar P with asymmetric tilts, but a lot of cameras aren't actually like this.

That said, with experience, the normal iterative focus method works pretty quickly as well, so it's not as if you can't control the plane of focus without asymmetric movements. Having cameras of various types, I do think the Sinar P is a bit faster to work with for tabletop shots, where swing and tilt can be more complicated, and that's really what it's designed for, and it's also handy for making a quick adjustment with a portrait subject. For landscape and architecture, asymmetric tilts don't seem like as much of a time saver.

Steve Hamley
14-Jan-2009, 10:43
Having used both an Ebony SV45U and a RW45, I can offer some insight as far as landscape use goes.

First of all it's important to understand that you can set the back at the same angle regardless of whether the movements are asymmetrical or not. What the asymmetrical movements do is save time. Usually, but not always, there is no iteration; focus on the swing/tilt line then swing/tilt to "focus". If you have time, the only thing you gain is convenience. Whether the convenience is worth it it pretty much a matter of opinion and will not be resolved in any forum. The only thing that's important is that you're comfortable using your camera. If you are, go out and shoot. In the end, the only way you'll really know is to try asymmetric and see if it floats your boat. That's why Ebony make both kinds.

But there are situations when the time saved is nice to have - sunsets and sunrises ore rapidly changing light with a foreground object are the times when I've been especially glad to have asymmetric movements, especially if encountering a "drive by" sunrise/sunset where seconds matter. Those of us that shoot sunrises and sunsets know that prime time frequently only lasts 2-3 minutes, maybe less, and a quick set-up is nice.

Cheers,

Steve

Paul O
14-Jan-2009, 10:58
Having read and participated in the thread on the UKLFPG website and having used LF cameras with base, centre and asymmetrical movements here's my take:
Using centre or base tilts requires the user to go through a process of focus, tilt (or swing), focus, tilt, focus, tilt, repeated until the near and far points on the composition are both sharp. This can take a number of moves - especially with "complex" subjects.

However, with asymmetrical tilts or swing this need to focus, tilt, etc etc is negated due to the asymmetric placement of the axis. So, you simply focus on the bottom gridded line (the background) and then employ rear asymmetric tilt until the part of the scene lying on the top gridded line (the foreground) is sharp and that's it! There is no need for the focus, tilt, focus, tilt ad infinitum procedure to get the background and foreground sharp! The scene is sharp!

It is also important to realise that ANY part of the scene falling on these gridded lines can be used - foreground, background it doesn't matter; just focus on whatever lies on one gridded line and then apply the movement until the part of the scene lying on the opposite gridded line is sharp! Couldn't be easier :D

A question for Frank - "As for a marketing ploy" I disagree completely - I think that asymmetric movements are a godsend! A bit like autofocus for LF :) I use an Ebony 45SU and being a non-folder combined with asymmetric movements I found the camera design a real help in adverse conditions. The speed and accuracy of the movements means that I KNOW that everything that I want to come out sharp will do just that. I was able to take photographs in a very windy Iceland last year in a fraction of the time that it would have taken with a folding camera with regular movements and I was able to concentrate on composition rather than "would the near and far be in focus" and get the camera back in the bag before my fingers fell off!

As far as the camera being a "status symbol" and "overkill" I would suggest that probably every LF camera built is overkill apart from (say) the Ebony RSW? Do any of us use even a fraction of the movements available on our cameras? Probably not!

Having laid out a load of cash for my Ebony 45SU back in 2002 I am one happy camper. I would not go back to a camera without asymmetric movements because I have experienced the benefits first-hand and not relied on people simply dismissing a feature they've never even tried:confused:

I challenge anyone to peer through the ground glass of my Ebony and not reappear with a big grin on their face when they see EXACTLY how useful this feature is! They will then be looking to sell a kidney to buy one!

CG
14-Jan-2009, 11:17
Short answer, asymmetric is just easier. Put one part of the scene in focus on the axis, and the swing tilt till the rest of the scene is optimal. Faster than try and fiddle approach. For studio where extra weight is no concern.

sheausong
14-Jan-2009, 11:26
Asymmetric movement at the back is more convenient to focus (at least for me) when dealing with lens mounted on recessed board.

RJC
14-Jan-2009, 11:51
I think that asymmetric movements are a godsend! A bit like autofocus for LF :) I use an Ebony 45SU ...

"The Ebony 45SU is, in my opinion, the easiest to deploy, fastest to set up fully featured field camera ever made. Its asymmetric rear tilt is so quick to use it is virtually the field camera equivalent of autofocus! It is so easy it sometimes feels like cheating." --- Joe Cornish

I have long been tempted by the 45SU but the additional weight when mountaineering has put me off so far. Maybe if I was shooting from the back of the car ...

Rob

Bjorn Nilsson
14-Jan-2009, 12:22
Apart from what have been said about the Ebony *U series, I really like the Sinar P. I try to use the P back even outdoors (making a Sinar C camera when combined with, in my case, an F2 front standart), as I can read the swing or tilt angle and transfer it to the front. I can then move the back to its original position so that I can keep the perspective without distortion. (Sometimes this matters, often it doesn't...)
For this once, I don't agree with Frank either. Asymmetric moves makes a lot of difference and saves a lot of time, so it's not "only a marketing hype".

//Björn

timparkin
14-Jan-2009, 12:31
I challenge anyone to peer through the ground glass of my Ebony and not reappear with a big grin on their face when they see EXACTLY how useful this feature is! They will then be looking to sell a kidney to buy one!

My take.. you can achieve what you want with centre or asymm. BUT

with center tilt....

1) focus on the centre line on something that lies on your desired plane

2) choose another point that you want in focus either above or below the center line, tilt until this comes in focus (lets assume this is below the line)

3) Check your content above the line to see if the plane of focus is now correct ... if not .. go back to 1)

With assym ...

1) focus the assym line (which is near the top of the gg) on something that lies on your desired plane

2) choose another point that you want in focus below the line

3) Check the focus looks ok in the centre of the picture .. if not .. go back to 1

Now I find it easier to

- extrapolate where the focus will lie based on the top and bottom lines

rather than

- extrapolate where the focus might be in the top of the picture based on the centre and bottom points

Humans are always better at extrapolating between things rather than extending beyond things.

Tim


Tim

Frank Petronio
14-Jan-2009, 14:47
Joanna -- yaw just makes it harder or impossible to get both swing and tilt angles optimal. Rarely is it an insurmountable deal-killing problem, just a hassle. But most landscapists or portrait photographers would never have t worry about it.

I don't like center tilt cameras either, base tilts are faster. whether or not they are asymmetrical.

Rakesh Malik
14-Jan-2009, 15:02
I have long been tempted by the 45SU but the additional weight when mountaineering has put me off so far. Maybe if I was shooting from the back of the car ...


That just means that you have to train harder ;)

I carry an SV45U everywhere nowadays, and I've been hiking (and snowshoeing) in the Cascades. I have used the Chamonix on some trips, but I did manage to cart my Ebony kit to the summit of Mt. Dickerman (9 miles round trip, 3800 ft elevation gain). It wasn't easy, but I made it :)

RJC
14-Jan-2009, 15:05
That just means that you have to train harder ;)



or get the sherpas to carry the beer ! ;)

Leonard Metcalf
14-Jan-2009, 15:26
Easier and faster to use. I love mine, and won't go back to a center or base tilt camera. I have gotta agree with Joe... I very rarely have to focus, tilt/swing/ focus, tilt/swing. focus, tilt/swing, focus, tilt/swing, focus, tilt/swing.... now I just do it once... sounds like an interesting dance...

It does `come down to subject matter though. If you were photographing flat planes all the time, center tilt would be fine. But I often have a foreground object and far distance that I want in focus, with nothing too much going on in the dead center.

Regards, Len

Rakesh Malik
14-Jan-2009, 15:46
or get the sherpas to carry the beer ! ;)

My sherpas usually end up carrying food and hot chocolate, and I bribe them with beer after the trip ;)

aphexafx
14-Jan-2009, 15:57
My Master PC has a variable axis tilt which I've never used - in other words I can raise the standards through the tilt axis, up to 40mm. So I can choose between symmetrical tilt and any asymmetric tilt up to 40mm off center?

el french
14-Jan-2009, 20:48
Thanks for all the replies. I think I have a better understanding of asymetric movements now :)

Would it be accurate to say there are 3 kinds of tilt or swing movements in today's cameras.
1. The axis of the tilt or swing is at the centerline of the focal plane.
2. The axis is below the centerline (for tilts), but still in the rectangle defined by the film.
3. The axis is below the centerline (for tilts) and below the film.

Could each of these be yaw free or not yaw free?

David A. Goldfarb
14-Jan-2009, 21:17
Could each of these be yaw free or not yaw free?

Yes, in theory, though I suppose in practice, option 3 tends not to be the only choiceon yaw free cameras. Some cameras have multiple kinds of tilt as well.

Yaw is only an issue if you point the camera up or down and apply swing--a fairly common situation in still life, not as much with landscape and architecture, and not so much of an issue with dynamic subjects like portraits, since subject motion is a bigger compositional issue than yaw. What happens on a camera that has yaw (and most do) is the image rotates on the groundglass due to the swing, and it seems like you can't get anything square. There are ways of repositioning the camera and using rise/fall/shift to avoid this situation usually, then as Frank says, just stop down for DOF, at least with 4x5", less so with 8x10"

aphexafx
14-Jan-2009, 23:40
My Master PC has a variable axis tilt which I've never used - in other words I can raise the standards through the tilt axis, up to 40mm. So I can choose between symmetrical tilt and any asymmetric tilt up to 40mm off center?

Nevermind, stupid question, I've figured it out for myself...

Leonard Evens
15-Jan-2009, 10:23
Thanks for all the replies. I think I have a better understanding of asymetric movements now :)

Would it be accurate to say there are 3 kinds of tilt or swing movements in today's cameras.
1. The axis of the tilt or swing is at the centerline of the focal plane.
2. The axis is below the centerline (for tilts), but still in the rectangle defined by the film.
3. The axis is below the centerline (for tilts) and below the film.

Could each of these be yaw free or not yaw free?

I believe you are correct, but when the axis is below the centerline, it is usually at or below the base of the standard and then it is called base tilt.

`yaw free' seems to mean different things to different people.

Let me try to explain what I think yaw refers to. It is based on how the term is used in navigation, describing the position of an airplane or ship.

Any rotation of a standard can be described by choosing an axis and then describing a rotation through some angle about that axis. Assume the standard is initially plumb. Typically, your choice of rotation axis is limited to two possibilities. If you rotate about a horizontal axis, it is called a tilt and if you rotate about a vertical axis, it is called a swing. Usually the swing axis will pass through the center of the standard and the swing is described as axial. The tilt axis however may be at the center of the standard. which is called an axial tilt, or at or below the bottom of the standard, which called a base tilt, or somewhere in the standard below the center, which is called an asymmetric tilt. (Some cameras allow you to tilt about more than one horizontal axis and/or, within limits, to place the horizontal axis at the center of perspective for the lens. The Alpa Swiss Orbix mechanism is such a device.)

Yaw refers to rotation about an axis perpendicular to the standard, usually through the center of the standard. You can't do this in any view camera I've heard of directly. (But in some cameras you can rotate the frame at will within the rear standard.)

By combining a tilt with a swing, it is possible in effect to place the rotation axis anywhere you need it, for example, when the plane of exact focus is skew to both horizontal and vertical lines.
But if you do that, depending on how you go about it, you may also rotate the standard about an axis perpendicular to it, i.e., you may produce some yaw. You can see if that has happened if the top and bottom of the standard are no longer horizontal. If it doesn't happen, the combination of tilt and swing is yaw free.

Now yaw of the front standard is essentially irrelevant because any rotation about the optical axis of the lens has no effect. On the other hand, yaw of the rear standard would result in the top and bottom of the frame no longer being horizontal. If your camera allows free rotations of the frame, then you can adjust this easily. You can also adjust it by rotating the whole camera, but doing that would probably upset the effect of any tilt/swing combination you used. (Of course, if you reserved combination of tilt and swing for the front standard, this problem would never arise.)

Unfortunately, the term `yaw free' is often used to refer to things which are unrelated to yaw.

One is whether or not you need to refocus after a tilt or a swing. Another is whether or not when you can accomplish a desired exact plane of focus with a single tilt followed by a single swing or whether you have to iterate tilt/swing combinations to get it right. There seems to be some belief that if there is no yaw of the standard then one or the other of these things may be easier. But that is not correct. These questions are essentially unrelated to rotation of the standard about a perpendicular axis, i.e. by yaw.

For example, whether or not you can obtain the desired subject plane by one tilt followed by one swing depends on the actual tilt and swing mechanisms employed in the camera. Thus, for my Toho FC-45X, it is not possible to do that. Generally, if you do first a tilt and then a swing, then you have to go back adjust the tilt, then adjust the swing, and keep doing that until you get it right. (With experience, only a small number of iterations is necessary.) But, if I do swing followed by a tilt instead, then I can get it right without iterating. Typically you can expect your view camera to allow it in one ordr but not the other, but which order is best varies with the camera.



In my article at

www.math.northwestern.edu/~len/photos/pages/vc.pdf

I completely analyzed rotations of the standards from a mathematical point of view in Section 9.
But it would only be accessible to someone with the right background.

In any case, you have to make sure you know what someone means by `yaw free' when you see that term used.

Bob Salomon - HP Marketing
15-Jan-2009, 12:03
Thanks for all the replies. I think I have a better understanding of asymetric movements now :)

Would it be accurate to say there are 3 kinds of tilt or swing movements in today's cameras.
1. The axis of the tilt or swing is at the centerline of the focal plane.
2. The axis is below the centerline (for tilts), but still in the rectangle defined by the film.
3. The axis is below the centerline (for tilts) and below the film.

Could each of these be yaw free or not yaw free?

Yaw only occurs on a camera where the tilt is below the swing. Yaw-free cameras usually have two tilt points on each standard. A bottom tilt that you use after inclining a camera to make the standards parallel to the subject and a fine tilt adjustment for image control.

Any camera that does have the tilt above the swing point becomes yaw free when it is mounted on its' side as the swing then becomes the tilt control. The Linhof TK has an extra spirit level for when the camera is used on its' side to be yaw free.

Leonard Evens
15-Jan-2009, 16:35
Yaw only occurs on a camera where the tilt is below the swing. Yaw-free cameras usually have two tilt points on each standard. A bottom tilt that you use after inclining a camera to make the standards parallel to the subject and a fine tilt adjustment for image control.

Any camera that does have the tilt above the swing point becomes yaw free when it is mounted on its' side as the swing then becomes the tilt control. The Linhof TK has an extra spirit level for when the camera is used on its' side to be yaw free.

This is related to my previous post as follows. The crucial issue is whether or not tilting moves the swing axis, and that depends on 'points of attachment', as Bob noted. For example, with my Toho FC-45X, the swing axis is fixed in the standard and is moved with it when I tilt. That means that a single swing/tilt operation is not going to be sufficient. On the other hand, the tilt axis remains fixed by the position of the rail and doesn't move when I swing. That means I can generally accomplish what I want with a single swing/tilt operation.

Other cameras are typically arranged so that the tilt axis says fixed when you swing and doesn't move with the standard. I think in those cases it is usually (possibly always) true that the swing axis moves when you tilt. So you have problems if you try swing/tilt.

It can be confusing trying to determine which of the `point of attachments' is below the other. The simplest way to see if you have yaw is to look and see, Tilt first and see what happens to the swing axis. Then swing and see if the standard yaws, i.e. its top and bottom remain horizontal.

I should clarify one point. You can always choose a single tilt followed by a single swing (or vice versa) such that the exact subject plane will be where you want it, at least after some refocusing. But calculating the required tilt and swing angles involves complex measurements and mathematical calculations which no one will want to make in the field. The point is whether you can do it with a single tilt followed by a single swing relying only on what you see on the ground glass, without making those calculations. In one case you can and in the other case you can't.

As I noted before, whether or not the standard rotates, i.e., yaws, is incidental with respect to focusing on a desired plane of focus. It turns out that in the usual cases, if you have yaw you also have an issue with focusing by a single combination. But, it isn't the yaw which `causes' the problem. To see what does cause it, you have to look in detail at what happens to the hinge line, as I did in my article.

An ideal situation for setting the exact subject plane would be one where you could rotate the standard about any desired axis in the standard directly. That would avoid the necessity of combining a tilt with a swing. For example, the standard could contain within it a circular disk with two oppsoite points of attachment to the fixed part of the standard but those points could be rotated within the standard. Those points of attachment would determine the axis which you could put anywhere within the standard that you wanted, and then you could simply rotate about that axis by an appropriate angle and get the desired subject plane. In that case, you would necessarily have yaw of the disk when the rotation axis wasn't vertical or horizontal. Presumably no one has designed such a mechanism because it would create problems with the bellows and keeping the camera light tight. But it does show why the yaw issue is separate from the focusing issue.

As I noted yaw is optically irrelevant since the image the lens produces is symmetric about the lens axis. Yaw of the rear standard is relevant because it may affect the relation between the sides of the frame and the horizontal and vertical directions in the scene, which can be a problem if you can't freely rotated the frame within the standard.

redu
23-Jun-2011, 03:08
I would like to resurrect this topic since i believe it is important to clarify this asymmetric movements thing. I think the evolution of the LF studio camera must have been like this.

1) The cameras with U type front standards and axial tilts were prone to YAW issue.
2) To eliminate yaw, the tilt mechanism has been lowered below swing mechanism. Hence the base tilt cameras come into the picture. But these cameras are prone to focus change with tilt action since tilt axis is out of the picture frame. If tilt axis was within the frame, either at center or wherever, we could first focus that line and perform tilt until the whole subject gets into focus.
3) At this stage some very good cameras with L type standards walk into picture. Like Horseman LX, Cambo Master and Linhof Kardan Master GTL. They have two tilt mechnisms. One at the bottom of the standard used to compensate yaw issue when the rail is inclined and a second one (which is axial to the lens) on the side of the L type standard to tilt the lensboard in order to perform focal plane adjustment. I am not sure but "may be" even tilting axis can be shifted with these cameras. (edit : I can confirm that Cambo Master has adjustable tilt axis up/down 40mm)
4) Sinar comes. They have their own designing principles with no U standards and no L standards; more portability without compromise. Likewise they have two tilt mechanisms though. The call it coarse tilt, and micrometer drive tilt. Coarse tilt is at the very bottom. It's only used to eliminate yaw when the rail is inclined. Micrometer drive tilt is above the corse one and used for focal plane adjustments. Now here comes the asymmetrical axis thingy. The micrometer drive makes the famous asymmetrical axial tilt.

http://www.sinar.ch/images/stories/produktuebersicht/p2/sinar_p2_02.gif

So the pivot tilt axis is within the picture frame. But why placed asymmetrically and not symmetrical? Actually i believe the one and only reason is to make the camera more stable and light. Since to shift the tilt axis further upwards towars the center of the lens and to keep the same range of tilt angles (back and forth) they had to design a much bigger and heavier micrometer drives both in the front and back, which would conflict with their designing principle in the first place. Also placing the tilt axis on the lower third might be a supporting photographic point as well. Sinar obviously successfuly turned this limitation into a marketting point. I believe Arca's orbix is another same thing with a fantastic name. However we should keep in mind that the cameras with L type standards have much less limitation at least on the axial tilt angle compared to Sinars and Arcas.

Bob Salomon - HP Marketing
23-Jun-2011, 03:29
I would like to resurrect this topic since i believe it is important to clarify this asymmetric movements thing. I think the evolution of the LF studio camera must have been like this.

1) The cameras with U type front standards and axial tilts were prone to YAW issue.
2) To eliminate yaw, the tilt mechanism has been lowered below swing mechanism. Hence the base tilt cameras come into the picture. But these cameras are prone to focus change with tilt action. Because tilt axis is out of the picture frame. If tilt axis was within the frame either at center or wherever we could first focus that line and perform tilt until whole subject gets into focus.
3) At this stage some very good cameras with L type standards walk into picture. Like Horseman LX, Cambo Master and Linhof Kardan Master GTL. They have two tilt mechnisms. One at the bottom of the standard used to compensate yaw issue when the rail is inclined and a second one (which is axial to the lens) on the side of the L type standard to tilt the lensboard in order to perform focal plane adjustment. I am not sure but "may be" even tilting axis can be shifted with these cameras.
4) Sinar comes. They have their own designing principles with no U standards and no L standards. Likewise they have two tilt mechanisms though. The call it coarse tilt, and micrometer drive tilt. Coarse tilt is at the very bottom. It's only used to eliminate yaw when the rail is inclined. Micrometer drive tilt is above the corse one and used for focal plane adjustments. Now here comes the asymmetrical axis thingy. The micrometer drive makes the famous asymmetrical axial tilt.

http://www.sinar.ch/images/stories/produktuebersicht/p2/sinar_p2_02.gif

So the pivot tilt axis is within the picture frame. But why placed asymmetrically and not symmetrical. Actually i believe the one and only reason is to make the camera more stable and light. Since to shift the tilt axis further upwards towars the center of the lens and to keep the same range of tilt angles (back and forth) they had to design a much bigger and heavier micrometer drive. Also placing the tilt axis on the lower third might be a supporting photographic point as well. Sinar obviously successfuly turned this limitation into a marketting point. However we should keep in mind that the cameras with L type standards have much less limitation at least on the axial tilt angle compared to Sinars.

The first yaw free camera was the original prototype Linhof Kardan camera which used a "knuckle" type joint so the tilt and swaing point were at the same point.

The Kardan was a very large and heavy camera so this feature was dropped on the first production version model but the name Kardan remained on Linhof monorail cameras. That is because Kardan was the term for that type of knuckle like device.

redu
23-Jun-2011, 04:19
Accordingly... I believe Linhof Kardan Master GTL should be one of the best 4x5 camera designed for studio product works.

Bob do you know whether Kardan Master's symetrical tilt axis could be shifted to an asymetrical position?

Bob Salomon - HP Marketing
23-Jun-2011, 05:46
Accordingly... I believe Linhof Kardan Master GTL should be one of the best 4x5 camera designed for studio product works.

Bob do you know whether Kardan Master's symetrical tilt axis could be shifted to an asymetrical position?

Which Master?

redu
23-Jun-2011, 06:06
Which Master?

GTL or TL. Axial tilt systems of these are identical i suppose. Can the tilt axis be shifted up and down?

Bob Salomon - HP Marketing
23-Jun-2011, 15:16
GTL or TL. Axial tilt systems of these are identical i suppose. Can the tilt axis be shifted up and down?

The TL was an optical axis camera. The GTL is a continuously variable assymetrical movement camera and it also has optical axis movements. It can be used either way.

John NYC
23-Jun-2011, 20:02
Short answer, asymmetric is just easier. Put one part of the scene in focus on the axis, and the swing tilt till the rest of the scene is optimal. Faster than try and fiddle approach. For studio where extra weight is no concern.

Exactly.