Front swing vs rear swing

Bob S said:

No, it controls subject shape as well as plane of sharp focus.
perspective is controlled by the angle of the camera to the subject.
back tilts and swings control subject shape!

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You are very ambiguous...


As we showed above, the term perspective is used in most different contexts:

-) the angle of the line between optical center of lens and central point of film.
This is the most commonly used context. The line of view between obstacles.

-) the angle between subject plane and perpendicular of film: perspective distorsion

-) the variation of distance to a staggered subject: perspective distorsion

Bob S said:

The books that you read should be based on the type of movements your camera has.

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Exactly. The Sinar book for monorails, the Linhof book for technical/field cameras. Naturally, both books are biased towards their own cameras, but the principles remain the same.

Kumar

B.S.Kumar said:

Exactly. The Sinar book for monorails, the Linhof book for technical/field cameras. Naturally, both books are biased towards their own cameras, but the principles remain the same.

Kumar

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The Sinar book is based on Sinar movements. Not much help with optical axis monorails like a Kardan. The Linhof movements book is based on a Technika, a Technika has neither axis moments front and back like most Kardans have.

Bob S said:

The Sinar book is based on Sinar movements. Not much help with optical axis monorails like a Kardan. The Linhof movements book is based on a Technika, a Technika has neither axis moments front and back like most Kardans have.

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Best would be the instructions, if available, for the camera one owns.

Bob S said:

The Sinar book is based on Sinar movements. Not much help with optical axis monorails like a Kardan. The Linhof movements book is based on a Technika, a Technika has neither axis moments front and back like most Kardans have.

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The basics are the same. A good lecturer/teacher would hint at different axis positions and the resp. results which can be quite complex (just think of 35mm cameras lens swing etc.)
You are right though: a uninitiated person reading a biased book will only learn half the truth so to say.

Bob,

Allow me to comment on your comments in the interest of clarification, especially for those just engaging with the subject of camera movements.

Bob S said:

1: perspective only changes in photography with the angle of the Camera to the subject.

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It's precisely the strict use of the term "perspective" to refer only to angles of view from center of lens to subject that is muddying the waters here. Many (if not most) of us use the term more loosely to also refer to the change in image shape on the ground glass when back swings/tilts are applied. This change in image shape is due to a change in the geometric projection onto the film and may possibly be more accurately described as distortion or shape change. Nevertheless, the use of the term "perspective" to describe this is so widespread that it seems pointless to insist on the distinction.

Bob S said:

2; there are 2 types of camera adjustments, direct or indirect.
A: direct movement use front and/or rear shifts and rise/fall only.
B; indirect movement uses front and/or rear tilts and swings only.
C: direct movement is done with a level camera and then the front and back sliding movement.

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To be perfectly honest, I've never heard the different types of movements categorized as "direct" and "indirect." Certainly rise-fall/shift is fundamentally different from tilt/swing. I'm curious where you got the terms. I have Stoebl and a few other guides to movements and don't seem to remember coming across them. FWIW, neither kind of movement requires any particular orientation of the camera. See below.

Bob S said:

D; indirect movements normally have an inclined camera and then tilts and swings.
E: tilting the camera up to include, for example, the top of the building, requires tilting the back to parallel to the subject.

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FWIW, I use tilts and swings with the camera leveled about 90% of the time, even in architectural work. The notion that tilts and swings are usually applied when the camera is not leveled is really off-the-mark. Maybe you're referring to the "point-and-tilt/swing" technique to achieve more rise-fall/shift? This technique can be used alone or in conjunction with rise-fall/shift and results in both standards being parallel, i.e., resulting in no effective tilt or swing (one just uses the tit/swing to get the standards parallel) and retaining the parallelism between film, lens and focus planes. Using tilt or swing alone is a very different thing and reorients the plane of sharp focus to something other than parallel to the film and lens planes.

Bob S said:

3; there are 3 types of camera movements, base,axis and asymmetrical.
With axis tilts the subject does not shift position. With base shifts it does. Asymmetrical are base shifts that prevent subject shifts.
Axis lens tilts do not use up image circle.

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Please note that with axis tilts/swings that it is only the center of the image that does not shift position. The sides of the image get moved around and focus shifts there. Base tilts (I know of no base swings...) move the entire standard, so general refocusing is required. Asymmetrical movements are just axis tilts/swings with the axis displaced to one end/side or the other to increase the distance between focus points (one of which always has to be on the axis) and, supposedly facilitate more rapid application of the movement. I'm about as fast with all the different kinds of movements.

On to "using up the image circle"... Swinging or tilting the lens stage moves the center of the image circle from film center, displacing it up, down or sideways. If you swing or tilt enough, you'll run out of image circle to cover the film, since it will be pointing somewhere else, resulting in vignetting. This repositioning of the cone of light projected by the lens which can end up with part of the film outside the circle of coverage is what we're talking about when we say, "swinging and tilting the lens stage uses up image circle." This is important even if we don't vignette, since many lenses are not nearly as sharp at the edges of the image circle as they are in the center.

Bob S said:

[Re: back movements changing perspective.] No, it controls subject shape as well as plane of sharp focus. Perspective is controlled by the angle of the camera to the subject. back tilts and swings control subject shape!

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Yes to everyone here. We're too busy arguing semantics. It is precisely the "change in subject shape" that many of us call a "change in perspective." Certainly, correcting convergence of parallel lines (one of the main uses of back movements) qualifies as a change in perspective in my book. One is moving the vanishing point around in the image, which Renaissance painters would have almost certainly described as changing perspective. Why not accept the use of the term "perspective" to refer to this as well? I think it would avoid a lot of confusion.

Bob S said:

That isn’t what I said but to correct your statement, image circle changes with aperture used and distance focused on, so your statement is partially correct. It does not change with camera movement.

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Again, we're discussing two different things. I think we all agree that camera movements per se do not change the size of the image circle. What does happen, however, is that the position of the image circle relative to the film changes a lot with rise-fall/shift and front tilts/swings. Since these latter present the danger of vignetting, the fact that the image circle is being displaced is good to keep in mind when applying movements. I agree, though, that we need to be more precise here and use some descriptor that is more precise and shows that we mean that the image circle is being moved around.

Thanks for the opportunity to clarify my description of things.

Best,

Doremus

Doremus,

you need to do some reading then, from books on photographic technique, not the internet.

and while you might use a technical term loosely it is incorrect and anyone that uses that type of description 9r reads the loose term should learn what the word really means.

AgX said:

You are very ambiguous...


As we showed above, the term perspective is used in most different contexts:

-) the angle of the line between optical center of lens and central point of film.
This is the most commonly used context. The line of view between obstacles.

-) the angle between subject plane and perpendicular of film: perspective distorsion

-) the variation of distance to a staggered subject: perspective distorsion

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No, Scheimpflug movements, tilts and swings, front and back, control the plane/zone of sharp focus. Additionally, back tilts and swings control subject shape.

Bob S said:

Doremus,

you need to do some reading then, from books on photographic technique, not the internet.

and while you might use a technical term loosely it is incorrect and anyone that uses that type of description 9r reads the loose term should learn what the word really means.

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I was using the term loosely, and I greatly appreciate Doremus stooping to answer on my level instead of making me feel stupid. Instead of trying to impress me, he was trying to help me.

Bob S said:

No, Scheimpflug movements, tilts and swings, front and back, control the plane/zone of sharp focus. Additionally, back tilts and swings control subject shape.

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I state how a certain term is used, and you comment on that by describing the effect of movements. Strange.

The book The View Camera by Harvey Shaman very well illustrates the effects of front swings vs. back swings with monorail camera, and gets past the bickering about proper/improper terminology that might be used by anyone in particular!

As I stated previously, and as illustrated by Shaman

• the primary offect of front swing is a change in the Plane of Focus vs. the plane of the subject (let us assume a cube),
• Back Swing changes the shape of the cube face...For example, if it started a square, it becomes a trapezoid (not parallel to the plane of the film); if it started as a trapezoid it can become a cube (when the plane of the film is swung parallel to the plane of the cube.

The placement of the pivot point on a particular camera determines whether or not a 'adverse yaw' happens, and how much you might have to correct focus after making a movement

Bob S said:

Doremus,
you need to do some reading then, from books on photographic technique, not the internet. And while you might use a technical term loosely it is incorrect and anyone that uses that type of description 9r reads the loose term should learn what the word really means.

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Bob,

Sorry if I offended you... I'm just trying to help out and clarify my own thinking here.

A couple of things: First, I've read a lot: studied Strobl's "View Camera Technique" (the Bible on the subject IMO) and many others. I've got a pretty extensive photographic library. I've written articles on view camera movements.

Second: We're not teaching technical courses on optics or geometrical projections here, rather discussing, in layman's terms, the practical application of camera movements. I think that the use of the word "perspective" as regards to changes in the image on the ground glass is not only justified, but correct.

The Oxford English Dictionary definition (emphasis added):

"perspective
noun

1 [mass noun] The art of representing three-dimensional objects on a two-dimensional surface so as to give the right impression of their height, width, depth, and position in relation to each other. --- [If that doesn't apply to camera movements and the changes on the ground glass, I don't know what does...]

‘the theory and practice of perspective’
as modifier ‘a perspective drawing’

1.1 The appearance of viewed objects with regard to their relative position, distance from the viewer, etc.

‘a trick of perspective’

1.2 [count noun] A view or prospect.

1.3 Geometry The relation of two figures in the same plane, such that pairs of corresponding points lie on concurrent lines, and corresponding lines meet in collinear points.

‘He then goes on to give theorems which relate to the perspective of plane figures.’ ..."

You see, I'm not using a technical term loosely, rather using a non-technical term correctly. I think it's more understandable that way, especially for those just coming to grips with camera movements. I'm really not trying to bicker, either; it just seems to me that being so hard-nosed about such things is counter-productive.

Best,

Doremus

AgX said:

Lens swing does not necessarily do so.
...

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Excellent point, and also tilt.
But I think only in theory with a single-nodal point lens, will the image not move. Many LF lenses have two nodal points, I think the image will shift slightly.

ic-racer said:

Excellent point, and also tilt.
But I think only in theory with a single-nodal point lens, will the image not move. Many LF lenses have two nodal points, I think the image will shift slightly.

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This is my experience. I always have to adjust a little when swinging or tilting the front because the image shifts slightly with the repositioning of the lens.

Best,

Doremus

I think the issue is the location of the swing axis relative to the rear nodal point, not only the distance between the two nodal points. If the swing axis is right on the rear nodal point, the image will move very little after swinging. (The front nodal point moves relative to the subject, but if the subject is far away, this is a small effect.) The further the swing axis is from the nodal point, the more the image moves. So it's a property of how the lens interacts with the camera geometry. I think if you took the same lens and mounted it on a recessed or extended lensboard, the amount of image motion during swing would change.


Edit to add: I believe this is also why using tilts/swings with a LF telephoto is generally regarded as a pain.

reddesert,

I think you are correct that much of the nodal displacement from the swing axis is due to camera design or lens mounting. BTW, I have a 300mm lens on a top-hat board and swinging it is more like tilting with base tilts (plus, mechanical vignetting occurs with just a little movement).

Best,

Doremus