Front swing vs rear swing

Ariston · Sep 21, 2019

Can someone tell me how these affect the image differently? Can I achieve the equivalent of front swing by pointing the camera to the side and swinging the back? Or is the effect completely different?

For instance, can I control focus of a fence on one side with just rear tilt, or will it screw with perspective?

AgX · Sep 21, 2019

Front and rear swing swing the focal plane.

Rear swing introduces perspective distorsion.

B.S.Kumar · Sep 22, 2019

I could explain this, but it is better for you to read a book or two. For the price of a couple of lens boards, here are my recommendations.

The Sinar "Photo Know How" book gives the best, most concise explanation for knowing everything the here is to know about view cameras and movements. It should be required reading for every photographer who works with view cameras. "Linhof Practice" is great for learning how to achieve those results with field cameras. There are other books also. "The View Camera" and "Using View Cameras" come to mind. But the first two books are the best.

Kumar

Ariston · Sep 22, 2019

Thanks, guys, both of you. I understand most movements, and I will go back and read my copy of The Camera (Adams) again, but I am trying to visualize what effect rear swings/tilts have on perspective. Google is not being helpful.

Luckless · Sep 22, 2019

Personally I found it easier to get my head around camera movements when I dropped the idea of 'a camera', and instead looked at it from the standpoint of a film/ground glass, a lens board [with its cone of view and cone of projection], and an object/scene.

The relative position and angle of the 'plane of capture' where the film/sensor/ground glass sit relative to the subject/object/scene, and how the lens is position and angled between them is what fundamentally matters. How you get them there becomes kind of a minor technical matter if you can manage to visualize what's going on, and then comes down to what's easier to adjust.

The camera's job is really nothing more than to give you a light tight space between the lensboard and the capture surface, while also [hopefully] providing a stable and reliable way to set and keep the desired alignment of everything.

A demonstration I found useful a few years ago was to mount the lens board in an open window with blackout curtains, and then rig a sort of bag-bellows to a ground glass such that we could move it around and look at the lens' projection pretty much freehand. [It was actually attached to a light stand with a simple U bracket that was salvaged off a cheap LED video light panel so it could be held steady while young students looked at it] Keep the room dark, and study how the focus and view changes as you move things relative to each other.

wiltw · Sep 22, 2019

Think of this simple relationship...

a front swing alters the Plane of Focus location in space
a rear swing alters the plane which determine the geometric perspective of the subject, i.e. parallel to a plane of the subject, that plane is captured rectilinearly; non-parralel to that plane captures that plane with receding perspetive. (I hope I expressed that properly)

Neil Grant · Sep 22, 2019

...rear swing and tilt control image shape. The screen is rotated around it's centre point - so the focus remains unchanged at this point. That can be very useful in setting up a camera. Front movements do not change image shape and the lens focus will change (because your are not rotating around the rear nodal point). Consider the OP's example of a fence at an oblique angle to the camera. With the cameras standards parallel only a small part will be in focus. Assume it's the centre point of the focus screen. The back can be swung to give focus all over - and the shape will change as well. The lens could be swung instead - the focus will change, though the plane of sharp focus may move closer to the plane of the fence. This process could be repeated until sharp focus is achieved all over the oblique fence - but it would a lot of time. A quicker alternative is to swing the back as before, note the angle of swing on the camera. Unswing the rear and transfer the swing angle to the front standard, then lastly fine-tune your focus on the rear standard. The camera will of course need standards with tilt/swing angles marked on them.

GLS · Sep 22, 2019

Yes, back tilt/swing affects image shape. Effectively this change is due to altering the magnification of the projected image to varying degrees across the frame, which is intuitive if you think about it:

The further the cone of projection travels the larger the size of the resulting image. By skewing the plane the image is projected onto you therefore cut into the cone at different levels of magnification. I hope this makes sense.

Leslie Stroebel's "View Camera Technique" is an excellent reference book, and gives a very comprehensive breakdown of camera movements.

Ian Grant · Sep 22, 2019

It actually depends on the placing of the film plane and lens board plane relative to the subject because we can also tilt and swing the whole camera as well. So one ism't better than the other it's just how you use them. Some LF cameras only have rear swing (or tilt), others just front swing (or tilt) and some have both, another factor is what shift is available.

It's better to just get out and practice with whichever camera you intend to use.

Ian

GLS · Sep 22, 2019

Ian Grant said:
It actually depends on the placing of the film plane and lens board plane relative to the subject because we can also tilt and swing the whole camera as well

True. My post above assumes a fixed orientation of the subject and lens plane relative to the back movement.

ic-racer · Sep 22, 2019

Any movement of the lens (front standard) changes the effective camera position. Moving the lens changes object relationships and perspective. Moving the camera back, does not change any object relationship and has no effect on perspective. If the subject is a a great distance with respect to the film size, both movements can look identical on the film plane. When doing close-up work or table-top work, moving the lens (front standard) can dramatically alter the perspective and composition.

Doremus Scudder · Sep 22, 2019

Both front and back swing alter the position of the plane of sharp focus.

The position of the camera back (i.e., film plane) relative to the subject also determines how the image is projected on the film. When you swing the back, you move part of it farther from your subject, basically enlarging that part of the subject; for the part that moves closer, the subject is rendered smaller. Back swing, in this regard, is primarily useful for 1) keeping horizontal lines parallel when the camera isn't exactly centered on the subject (think pointing your camera at a brick wall at a slight angle and then swinging the back parallel to it to keep the horizontal lines even), or 2) emphasizing the convergence of parallel lines (think the same brick wall, but swing the other way to make the parallel lines converge more distinctly). Of course, when using the back swing for altering the shape of your subject, you may have to use lens swing to get the desired focus after positioning the back for the perspective you want (I do this often when working in cities).

Another handy use of back swing is to deal with focus issues when front swing is not available, either because it is absent or because the lens being used doesn't have enough coverage to allow swing to be used. If you want to deal with perspective rendering in this case, it is necessary to set up the camera with the needed swing already applied and position the camera back correctly relative to the subject. In practice, this often means several iterations of pointing/swinging to get both desired perspective and focus. Fiddly, but doable when nothing else is available.

FWIW, the same applies to front and back tilts, just displaced 90°.

A word about "perspective." Strictly speaking, the position of the lens determines the relationship of objects in the scene to each other, and, hence, the perspective. The position of the camera back relative to the subject determines the distortion that is introduced by projection. ic-racer is technically correct that moving the lens, in effect, changes camera position. This is quite obvious when doing close-up work. However, for most working distances, swinging or tilting the lens can be mostly disregarded. And, the use of the word, "perspective," to describe the change in the size of the projection (and especially the rendering of parallels) when changing the film position relative to the subject is so widespread that I think it is a bit nit-picky to insist on using the word only in relation to camera position. I find that students and laymen relate very quickly to the concept of correcting parallels or exaggerating convergence by describing it as changing "perspective." IM-HO, that's a fine general use of the term.

Best,

Doremus

Ariston · Sep 22, 2019

Doremus Scudder said:
Both front and back swing alter the position of the plane of sharp focus.

The position of the camera back (i.e., film plane) relative to the subject also determines how the image is projected on the film. When you swing the back, you move part of it farther from your subject, basically enlarging that part of the subject; for the part that moves closer, the subject is rendered smaller. Back swing, in this regard, is primarily useful for 1) keeping horizontal lines parallel when the camera isn't exactly centered on the subject (think pointing your camera at a brick wall at a slight angle and then swinging the back parallel to it to keep the horizontal lines even), or 2) emphasizing the convergence of parallel lines (think the same brick wall, but swing the other way to make the parallel lines converge more distinctly). Of course, when using the back swing for altering the shape of your subject, you may have to use lens swing to get the desired focus after positioning the back for the perspective you want (I do this often when working in cities).

Another handy use of back swing is to deal with focus issues when front swing is not available, either because it is absent or because the lens being used doesn't have enough coverage to allow swing to be used. If you want to deal with perspective rendering in this case, it is necessary to set up the camera with the needed swing already applied and position the camera back correctly relative to the subject. In practice, this often means several iterations of pointing/swinging to get both desired perspective and focus. Fiddly, but doable when nothing else is available.

FWIW, the same applies to front and back tilts, just displaced 90°.

Hope this helps,

Doremus

Doremus, thank you! That description of the effect on the brick wall is exactly what I needed. I knew it changed the "perspective," but could not visualize HOW it changed the perspective. Thank you for the education.

AgX · Sep 23, 2019

Doremus Scudder said:
A word about "perspective." Strictly speaking, the position of the lens determines the relationship of objects in the scene to each other, and, hence, the perspective. The position of the camera back relative to the subject determines the distortion that is introduced by projection. ic-racer is technically correct that moving the lens, in effect, changes camera position. This is quite obvious when doing close-up work. However, for most working distances, swinging or tilting the lens can be mostly disregarded. And, the use of the word, "perspective," to describe the change in the size of the projection (and especially the rendering of parallels) when changing the film position relative to the subject is so widespread that I think it is a bit nit-picky to insist on using the word only in relation to camera position. I find that students and laymen relate very quickly to the concept of correcting parallels or exaggerating convergence by describing it as changing "perspective." IM-HO, that's a fine general use of the term.

I did not use the term "perspective" but "perspective distorsion". As you indicated one can argue even on the latter, as it does not involve change in camera position. But do you know a term technically more correct?
One could use just "distorsion", but only if the circumstance (back swing) is hinted at, as there are various kinds of distorsion.

AgX · Sep 23, 2019

ic-racer said:
Any movement of the lens (front standard) changes the effective camera position.

Lens swing does not necessarily do so.
Only if the image circle is too small for the format and one has to react on it by a back movement,or when the swing axis is not at optical center.

M. Axel Wikstrom · Sep 23, 2019

Both front and rear swing/tilt alter the effective plane of focus.

Front swing/tilt consumes image circle and puts part of the image near the edge of the image circle, thereby enlarging the image near that edge. This is due to projection distance (from optical center of the lens to the edge of the image circle, as compared to the optical center to the middle of the image circle) - this is especially prominent with short focal length lenses; less so with long lenses.
Rear swing/tilt does not consume image circle, and does not enlarge the portion of the image that's focused closer (as much). This is because you're working only with the relative center of the projected image, not so much the edges.
For perspective control, for example: keeping lines parallel, one would better use rise-fall and shift.
Swing/tilt/rise or fall/shift can be used together for the desired effect.

pbromaghin · Sep 23, 2019

Large Format Camera Practice by Joseph Foldes is the best "how to" book I've ever found, not just within photography, but on any subject, . It breaks the camera down into it's simplest elements. The words and pictures match exactly, the language is simple, there is not one necessary word missing, and not one unnecessary word included.

Doremus Scudder · Sep 23, 2019

Ariston said:
Doremus, thank you! That description of the effect on the brick wall is exactly what I needed. I knew it changed the "perspective," but could not visualize HOW it changed the perspective. Thank you for the education.

Glad to be of help. There are so many ways to get your head around this that it's really a case of "the more, the merrier" as far as explanations go.

AgX said:
I did not use the term "perspective" but "perspective distorsion". As you indicated one can argue even on the latter, as it does not involve change in camera position. But do you know a term technically more correct?
One could use just "distorsion", but only if the circumstance (back swing) is hinted at, as there are various kinds of distorsion.

AgX,
The argument about how "perspective" is defined goes on and on here. I prefer not to get too involved in that, rather just make sure I qualify my terms enough so that it's clear what I'm trying to communicate.

Really, though, it is good to distinguish between the relation of lens position relative to the subject and the position of the film relative to the cone of light the lens projects. The lens-to-subject distance really determines camera position, with the film just tagging along at the right distance for focus. Any applied movements change the film position in the cone of light that the lens is projecting. The "standard" position is centered in the cone and perpendicular to a line from the center of the lens to the center of the film. That gives us the default lens projection and is the norm for fixed-body cameras. View cameras enable us to deviate from this norm and thereby change the projection and the relative sizes of different parts of the subject from "normal." What we choose to call this is really irrelevant as long as we understand the principle and apply it correctly. I have no qualms using "perspective" in discussing this, but sticklers like to reserve "perspective" for the relationship of subject elements from the lens position. That leaves no commonly-used term to describe the changes in subject sizes on the film when applying movements. I'll continue to use perspective for both.

M. Axel Wikstrom said:
Both front and rear swing/tilt alter the effective plane of focus.

Front swing/tilt consumes image circle and puts part of the image near the edge of the image circle, thereby enlarging the image near that edge. This is due to projection distance (from optical center of the lens to the edge of the image circle, as compared to the optical center to the middle of the image circle) - this is especially prominent with short focal length lenses; less so with long lenses.

Precisely. I'll emphasize that it is the difference in the ratio of the distances from the center to the edge of the image circle that determines how much relative enlargement is introduced. Really, just a function of the projection.

M. Axel Wikstrom said:
Rear swing/tilt does not consume image circle, and does not enlarge the portion of the image that's focused closer (as much). This is because you're working only with the relative center of the projected image, not so much the edges.

Well... since it's the ratio of distances between nearest and farthest lens-to-film distance, yes, anytime you tilt or swing the back, you're going to increase the distance on one end/side and reduce it on the other, introducing enlargement/diminution. Yes, this is somewhat independent of the angles of the lens projection, but still, it's altering the projection in much the same way with the same general effect.

M. Axel Wikstrom said:
For perspective control, for example: keeping lines parallel, one would better use rise-fall and shift.

Note that using rise-fall/shift moves the film closer to the edge of the image circle and changes the relation of lens-to-film distances. It is precisely the enlargement of one end of the film in relation to the other that "corrects" converging verticals. While rise-fall/shift are easy, they are just one way to get a desired relationship between lens and film. Point-and-swing/tilt will do exactly the same thing. Using both techniques together results in more effective rise/shift.

M. Axel Wikstrom said:
Swing/tilt/rise or fall/shift can be used together for the desired effect.

Again, it's really just the relative position of lens and film that matters. I often think of where I want the lens to be relative to the film in space and figure out from that which movements I can most simply apply to get that relationship. There are often many ways to achieve the very same lens position to film position relationship.

Best,

Doremus

M. Axel Wikstrom · Sep 24, 2019

Doremus Scudder said:
Glad to be of help. There are so many ways to get your head around this that it's really a case of "the more, the merrier" as far as explanations go.

AgX,
The argument about how "perspective" is defined goes on and on here. I prefer not to get too involved in that, rather just make sure I qualify my terms enough so that it's clear what I'm trying to communicate.

Really, though, it is good to distinguish between the relation of lens position relative to the subject and the position of the film relative to the cone of light the lens projects. The lens-to-subject distance really determines camera position, with the film just tagging along at the right distance for focus. Any applied movements change the film position in the cone of light that the lens is projecting. The "standard" position is centered in the cone and perpendicular to a line from the center of the lens to the center of the film. That gives us the default lens projection and is the norm for fixed-body cameras. View cameras enable us to deviate from this norm and thereby change the projection and the relative sizes of different parts of the subject from "normal." What we choose to call this is really irrelevant as long as we understand the principle and apply it correctly. I have no qualms using "perspective" in discussing this, but sticklers like to reserve "perspective" for the relationship of subject elements from the lens position. That leaves no commonly-used term to describe the changes in subject sizes on the film when applying movements. I'll continue to use perspective for both.

Precisely. I'll emphasize that it is the difference in the ratio of the distances from the center to the edge of the image circle that determines how much relative enlargement is introduced. Really, just a function of the projection.

Well... since it's the ratio of distances between nearest and farthest lens-to-film distance, yes, anytime you tilt or swing the back, you're going to increase the distance on one end/side and reduce it on the other, introducing enlargement/diminution. Yes, this is somewhat independent of the angles of the lens projection, but still, it's altering the projection in much the same way with the same general effect.

Note that using rise-fall/shift moves the film closer to the edge of the image circle and changes the relation of lens-to-film distances. It is precisely the enlargement of one end of the film in relation to the other that "corrects" converging verticals. While rise-fall/shift are easy, they are just one way to get a desired relationship between lens and film. Point-and-swing/tilt will do exactly the same thing. Using both techniques together results in more effective rise/shift.

Again, it's really just the relative position of lens and film that matters. I often think of where I want the lens to be relative to the film in space and figure out from that which movements I can most simply apply to get that relationship. There are often many ways to achieve the very same lens position to film position relationship.

Best,

Doremus

I teach workshops on the subject and like to keep things as simple as possible, but encourage students to experiment with their cameras and lenses. I start with the basics of how lenses are designed to project an image and go from there.

Vaughn · Sep 24, 2019

Thanks, Doremus.

For some odd reason it took me quite awhile to realize pointing the camera up and then making both standards vertical was the same thing as keeping the camera level and just using front rise. Silly, I know. But I do remember tying the bellows into knots, only to have to go back to zero and try again...always with much simpler moderate movements. The GG doesn't lie!

Bob S · Sep 24, 2019

1: perspective only changes in photography with the angle of the Camera to the subject.
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.
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.
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. Asymetrrical are base shifts that prevent subject shifts.
Axis lens tilts do not use up image circle.

AgX · Sep 24, 2019

Bob S said:
Axis lens tilts do not use up image circle.

Image circle does never change with any movement other than focusing (circle widening at macro scale).

Bob S · Sep 24, 2019

AgX said:
Front and rear swing swing the focal plane.

Rear swing introduces perspective distorsion.

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!

Bob S · Sep 24, 2019

B.S.Kumar said:
I could explain this, but it is better for you to read a book or two. For the price of a couple of lens boards, here are my recommendations.

The Sinar "Photo Know How" book gives the best, most concise explanation for knowing everything the here is to know about view cameras and movements. It should be required reading for every photographer who works with view cameras. "Linhof Practice" is great for learning how to achieve those results with field cameras. There are other books also. "The View Camera" and "Using View Cameras" come to mind. But the first two books are the best.

Kumar

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

Bob S · Sep 24, 2019

AgX said:
Image circle does never change with any movement other than focusing (circle widening at macro scale).

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.

Front swing vs rear swing

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