Advantages of Back Shift

[Greg Liscio]

I am ready to purchase an Ebony SV45U or SV45U2, the difference being the SV45U2 has back shift.

I know that back shift permits moving the film while keeping the lens in the same perspective. I'd like to know what other advantages you have realized, and what your opinion of this feature overall is.

Thankee

[erie patsellis]

Back movements are used to alter or correct the geometry of the image, even in a field camera I'd consider them essential for my work.

[Andrew O'Neill]

Back movements are used to alter or correct the geometry of the image,

Not back shift, as Greg is inquiring about. Greg, I think you already stated the "main" advantage of rear shift over front shift...the image perspective isn't altered.

[Don7x17]

Not back shift, as Greg is inquiring about. Greg, I think you already stated the "main" advantage of rear shift over front shift...the image perspective isn't altered.


Back tilt and back swing modify the image perspective.
Back shift (and back rise/fall if you have it)just moves the image around in the cone of light of the lens
(and any swing or tilt applied before using shift is what changes the perspective....when you shift, you've moving within this modified cone)

[David Karp]

In addition to the benefit you mentioned, back shift is nice when you have a long lens. You don't have to reach all the way to the front standard to accomplish a shift.

[Andrew O'Neill]

Don7x17, How does back tilt and swing modify image perspective? Doesn't it just alter image geometry? What am I missing here?

[Don7x17]

You can make objects on one side of a tilt or swing change image size on the film (with respect to the other.). Weston used it a lot.

With Architectural photography its really obvious:
Its most obvious if you take an image of a building -- looking at a corner of a building so both sides are visible (135 degrees between line of sight and either plane of building side), with enough lens image circle coverage, you can make one or the other sides of the building appear square at the extreme expense of the other side.

And these movements are required in architectural photography (with view camera) to remove keystoning of buildings as you point the camera upwards to get the whole face of the building.

You're changing film to lens distance...that's why back swing and tilt change the perspective

Give it a try on your camera (presuming you have tilt/swing on rear).

Note that tilt and swing on front just changes the plane of focus.

[Lachlan 717]

I use back shift for portraits with my Petzval.

I focus with the subject centered in the frame (i.e. the sharp part of the lens).

If I want the subject (either whole person or perhaps their eyes) off center, I shift the back, leaving the subject still in the sharp part of the lens.

Only issue here is light fall-off towards one side if I am not careful.

Lachlan.

[Nicholas F. Jones]

Back shift comes in handy for me when shooting with a large and heavy camera and when the subject is upright, rectilinear, with straight lines, e.g. a building. The problem is usually to get the subject both centered and squared up. Even with a large structure, being off by just a few inches will often be painfully noticeable--and unsettling and irritating--in a big enlargement.

My usual procedure is to do my best to find the center by measurement and guestimating, place the tripod on that centerline, then use the grid on the ground glass to square the subject. But most times I find I'm a little off, that when squared the subject is no longer centered on the ground glass. So, it's either move the camera or use back shift. Back shift in other words is a much easier and more precise alternative to lateral movement of tripod and camera.

The bigger and heavier your set-up, the greater the advantage. Since my 8x10 has no back shift, I've given up using it for these centered-and-squared shots and take the 5x7 Canham instead, which does.

[Donald Miller]

If a camera has front shift then rear shift has no measurable benefit other than allowing greater lateral displacement. Since the original post asked the question of rear shift I will not engage in discussions of tilt and swing since they are not applicable to the discussion at hand.

Best regards,
Donald Miller

[evan clarke]

Back shift, rise and fall are the best way to fine tune your composition...Evan Clarke

[Brian Ellis]

Don7x17, How does back tilt and swing modify image perspective? Doesn't it just alter image geometry? What am I missing here?

You're not missing anything. People are misusing the word "perspective." I've mentioned this a couple times here and was chastised as a nit-picker so I wasn't going to mention it again but your question perfectly illustrates why it's good to use language correctly. Tilts and swings don't change perspective. The only thing that changes perspective is moving the camera position.

[Don7x17]

Lets not ignore the fact that a combination of front swing/tilt and back swing/tilt creates indirect displacement, which is a means for gaining greater shift than available with just front swing/tilt, etc. So swing/tilt is still relevant in discussions of back shift/rise.

[Andrew O'Neill]

If a camera has front shift then rear shift has no measurable benefit other than allowing greater lateral displacement.

There is measurable difference. Once when I was shooting close to some barbed wire of an old building, I noticed when I shifted the lens, the barbed wire changed its location slightly with the building. Moving the back had no effect. Moving the lens changes the perspective, not the back.

[Don7x17]

There is measurable difference. Once when I was shooting close to some barbed wire of an old building, I noticed when I shifted the lens, the barbed wire changed its location slightly with the building. Moving the back had no effect. Moving the lens changes the perspective, not the back.

Andrew
You've merely repositioned the lens relative to a close subject(barbed wire). You'd see the same effect if you repositioned the tripod with the no movements and the physical location of the lens moved (with the camera and tripod) to match the position you used.

This is not the same as changing the perspective by moving the back (tilt/shift)while the lens stays in the same location. give it a try.

There were several copies of Simmon's Using the View camera for sale recently -- try to find a copy and take a look at the effects.

[Doug Dolde]

You can shoot two sheets to stitch a panorama, almost 4x10 depending on how much shift is avaiable. Just shift full left for one shot then full right for the second.

[drew.saunders]

You'd see the same effect if you repositioned the tripod with the no movements and the physical location of the lens moved (with the camera and tripod) to match the position you used.

That's the main advantage of rear shift for me: sometimes it's difficult to move the tripod just a wee to the left or the right, especially in the field where you may have to fiddle to find a stable position for the tripod, and moving the rear standard is a lot easier.

For this shot: http://farm4.static.flickr.com/3660/3301862332_caf4577d6f_o.jpg I had to find a spot near the fence where the tripod legs were stable (it may be hard to tell, but this cemetery is on a hillside), but it wasn't exactly where I wanted the camera, so I needed a fair bit of rear shift and rise to get the back in the desired position.

Drew

[David Karp]

There is measurable difference. Once when I was shooting close to some barbed wire of an old building, I noticed when I shifted the lens, the barbed wire changed its location slightly with the building. Moving the back had no effect. Moving the lens changes the perspective, not the back.

This is why back shift is useful, even if you have front shift. Front shift is like subtly moving the camera to one side or the other. Back shift is just moving from side to side in the image circle without moving the camera. The former can alter the relationship between the subjects. The latter does not.

This is the reason that unless I need to alter the plane of focus, I prefer to use back movements as much as possible, and why a lightweight monorail is nice, even though harder to pack than a field camera.

[Nicholas F. Jones]

With sufficient image circle, you can shoot a triptych, one zeroed, one full left, one full right. There's some overlap, which could be cropped out, but with an appropriate subject I like to leave it. With less image circle, there'll be vignetting, which I also like to leave if the particular lens's image remains sharp right up to the edge of the IC.

[Andrew O'Neill]

You'd see the same effect if you repositioned the tripod with the no movements and the physical location of the lens moved (with the camera and tripod) to match the position you used.

Yes, but I didn't want to move the tripod. I already had the main comp down but it needed a wee bit of tweaking. Only the back shift could accommodate this without changing the perspective.

Thanks but, I have several books on view cameras (not the Simmons book), and quite a bit of experience using mono-rails and field cameras. :)

[Nathan Potter]

If a camera has front shift then rear shift has no measurable benefit other than allowing greater lateral displacement. Since the original post asked the question of rear shift I will not engage in discussions of tilt and swing since they are not applicable to the discussion at hand.

Best regards,
Donald Miller

Donald that is exactly how I see it. When talking shift within the image circle both front and rear standard effects are interchangeable. If one has shift capability with both front and rear standard then possibly a greater total movement can be had. The real difference is found in operational convenience insofar as it may be easier to access the rear standard while buried under a dark cloth.

I'll go a bit further than Donald and say that in some instances when both swing and tilt are required as well as shift there may be more convenience in using rear shift
due to the complexity of the image manipulation. You'll certainly be working under the darkcloth - and in a world of complex adjustment hurt.

Nate Potter, Austin TX.

[David Karp]

. . . When talking shift within the image circle both front and rear standard effects are interchangeable. . . .

Unless I am missing something, this is misleading. Front or rear shift each accomplish shift. However, as illustrated in all of the texts, front shift results in a change in the relationships between the objects in the photograph, whereas rear shift does not.

Sometimes this is important. Other times it is not.

[Andrew O'Neill]

front shift results in a change in the relationships between the objects in the photograph, ...

Exactly. Which translates to a change in "perspective".

[Mark Barendt]

Okay,

Here's my understanding.

If the front (the lens) remains fixed in space then the image circle it projects will remain constant also.

If that is true then rear shift (or rear rise or drop along the other axis) only moves the film/Ground Glass to the left or right of the image circle effectively changing only what part of the image circle is viewed.

Conversely if the back was fixed and the front was shifted the image circle would just move sideways and you would end up with essentially the same composition/effect as above.

The composition in either case would change from the "original" but given equal but opposite offset the end result would be essentially the same.

Is this right?

[David Karp]

. . . but opposite offset the end result would be essentially the same.

Is this right?

No.

Envision this: A block is lined up in front of an orb. The camera is lined up so that when all movements are zeroed out the block is exactly in front of the orb.

If you shift the back you will move around in the image circle, but the relationship between the block and the orb will remain the same. The block will be exactly in front of the orb.

If you shift the lens, things will not be the same. You will see more of the orb, and the block will not be exactly in front of the orb. This is because the viewpoint of the lens, and thus the camera, will have changed. The lens is "peering" to the side of the block, to see more of the orb.

If you have Stones' A User's Guide to the View Camera," or Simmons' similar book you can see illustrations of how rise or shift result in different effects depending on whether applied to the front or back standard.

[Andrew O'Neill]

...and you can see an example of this in Ansel Adams' book, The Camera. I believe he was shooting a house porch from the outside and in the 1st shot you can see his reflection and camera in the window. For the 2nd shot he picked up and moved the camera slightly to the right, panned the camera back to the left to regain the same composition, then swung both the front and rear standards so that they were parallel to the house. Not only can you no longer see Adams and camera in the 2nd shot, but you can also see more of the right side of the posts. Only a change in perspective can this happen (moving the camera and/or lens).

[Doremus Scudder]

Back to the original question, which seems to be, "are there any advantages to having back shift instead of/in addition to front shift."

As the above discussion illustrates, front shift (and rise/fall, which are the same movement only 90° opposed) moves the position of the lens in relation to the subject and therefore changes the viewing position and thus the perspective. Back shift does not do this.

If your method is based on exact camera position and then trimming up the image framing with shifts, then back shift is an ideal thing to have.

However, it is good to keep in mind that the change in position/perspective caused by shifting the lens is usually insignificant except when some parts of the scene are very close to the lens.

I have several wooden folding field cameras. The one I am currently using in Europe has front shift only. My Wistas in the States have back shift only. For 95%+ of the shots I use shift on (which is rather often, since I shoot a lot of urban scenes in Europe), the slight perspective change caused by the front shift makes no significant difference in the composition of the photograph and can be ignored.

Sometimes, however, I find I have to compensate by moving the tripod by the same amount as the shift in the opposite direction. Sometimes I can do this by loosening the camera mounting screw and sliding the entire camera to one side a little bit.

The times I have to do this are so rare that I would not hesitate to buy a camera with front shift only if I liked the other features despite the fact that back shift is probably a bit easier to apply and use. I would not, however, buy a camera with no shift at all; I find it indispensable. The ideal situation would be to have both front and back shift, which one could combine for a larger total shift as well as choosing one for its particular application in a certain situation.

Hope this helps the OP make a decision.

Best,

Doremus Scudder

[Leonard Evens]

If a camera has front shift then rear shift has no measurable benefit other than allowing greater lateral displacement. Since the original post asked the question of rear shift I will not engage in discussions of tilt and swing since they are not applicable to the discussion at hand.

Best regards,
Donald Miller

I agree. Usually I use front shift, but if I can't get enough lateral shift that way I use both.

There are few situations where the shift in the center of perspective with front shift is an issue. It would matter in close-ups. Otherwise the relative shift in point of view is usually too small to matter. It can also matter if you want to stitch two pictures together to form a composite with an effective larger angle of view. I've done this when photographing a building facade where I couldn't get far enough back to include the whole building in the frame with my 75 mm lens.

[Nathan Potter]

Yes, I admit to a generalization on front vs rear shift. Generally a shift in the lens relative to the film plane makes precious little change in perspective for more distant subjects. But as Doremus points out there is increasingly more dramatic changes in perspective as one moves the subject closer and closer to the lens and the lens is shifted. For instance at 1:1 the perspective is dramatically altered. :) :)

Nate Potter, Austin TX.

[Mark Barendt]

No.

Envision this: A block is lined up in front of an orb. The camera is lined up so that when all movements are zeroed out the block is exactly in front of the orb.

If you shift the back you will move around in the image circle, but the relationship between the block and the orb will remain the same. The block will be exactly in front of the orb.

The relationship of the block (the lens and the image circle) and the orb (the subject) remain the same but there is a third element, the back.

Draw a line, using the center of the film/back and the center of the lens as the defining points in each case. In the zeroed case the film's view is straight, ad any shift, rise, or fall and what the film will see (the view of the orb) changes.

If I move the front right or the back left the line of view would move to the right on the orb/subject.

[Andrew O'Neill]

So that is the main difference between front shift and back shift. Doesn't matter how little change there is with distant objects when shifting the front, there still is some change as opposed to none if you shift the back.

[David Karp]

. . . If I move the front right or the back left the line of view would move to the right on the orb/subject.

If you move the front, the lens is moving, so the film "sees" something different, just as it would if you move the camera. You are moving both the lens, and, therefore, the image circle.

If you move the back, the lens stays in the same place. The only thing that happens when you shift the back is that you are moving the film around in the same image circle that was created by the lens before you moved the back. The line of view does not change.

[David Karp]

. . . However, it is good to keep in mind that the change in position/perspective caused by shifting the lens is usually insignificant except when some parts of the scene are very close to the lens.

* * *

. . . I would not hesitate to buy a camera with front shift only if I liked the other features despite the fact that back shift is probably a bit easier to apply and use. I would not, however, buy a camera with no shift at all; I find it indispensable.

Agreed. I purchased a Walker with rear shift, but if it had only front shift I still would have purchased it.

Nevertheless, it is good to keep the ideas raised in this thread in mind when applying shifts, rise, or fall in the field, even if it is rarely a problem in the field. On several occasions when using a camera with front movements only (rise in this case) applying the movements caused some lines in the photograph to become tangent. I found this undesirable, so I had to adjust the camera position a few times to get what I wanted. I felt that the final photograph would have suffered if I just used the rise. This would not have been an issue if the camera had back rise. As a result of these experiences, I am careful when in a situation where I can't use the back.

[Mark Barendt]

If you move the front, the lens is moving, so the film "sees" something different, just as it would if you move the camera. You are moving both the lens, and, therefore, the image circle.

If you move the back, the lens stays in the same place. The only thing that happens when you shift the back is that you are moving the film around in the same image circle that was created by the lens before you moved the back. The line of view does not change.

I agree that the lens's line of view does not change, but the film's line of view within the circle, represented by the composition shown on the film/ground glass, can and does change as it moves around the circle with back shift, rise, or fall.

With enough backshift and a roll film back you could run the roll film vertically shift full right take one shot then shift full left and take a second shot of a completely different composition and no overlap.

[Alan Davenport]

I know that back shift permits moving the film while keeping the lens in the same perspective. I'd like to know what other advantages you have realized, and what your opinion of this feature overall is.

IMO there are no other advantages to rear shift, vs front shift. However, the ability to shift the film while retaining the relationships between foreground and background is a big one.