What ever happened to rear swings AND tilts on field view cameras?

[rdenney]

I'm not experienced enough to add anything that would clear this up. But I have a related question. The camera I bought, a Chamonix 45H-1, has tilts and shifts available on both standards as well as asymmetrical tilt on the rear standard only. Why would they set asymmetrical tilt up on the rear?
https://www.chamonixviewcamera.com/cameras/45h1

When tilting, the axis of the tilt is the only place focus won’t change when you adjust tilt. It doesn’t look like that camera (as with many field cameras) has rear focusing with respect to the tripod mount (and even if it did, it does change the magnification slightly, though has never bothered me). (Edit: scratch that—the whole rear bed racks in and out from the center section.) Monorail cameras are usually more flexible in this regard—front and rear independently focus.

Moving the tilt axis into the image area provides one line of preserved focus. But that line’s location will be a compromise, and will require luck for it to be right where you want to preserve focus when tilting. I have never been that lucky—I always have to refocus when tilting.

Another thing—the Cambo put the axial tilts at the mid-point, but for that to work it also has to the set back from the standard to align with the film plane/ground glass. That puts knobs in the way of sliding in film holders. Dealing with that issue requires further complexity. The Sinar P uses a curved track below the standard, so the tilt axis floats in air. Beautiful but not cheap. But the Chamonix tilts around an axis well forward of the film plane, so the line where focus is preserved is going to move all over the place as you tilt.

Rick “whose Sinar P also has asymmetric tilts” Denney

[Larry Gebhardt]

When tilting, the axis of the tilt is the only place focus won’t change when you adjust tilt. It doesn’t look like that camera (as with many field cameras) has rear focusing with respect to the tripod mount (and even if it did, it does change the magnification slightly, though has never bothered me). (Edit: scratch that—the whole rear bed racks in and out from the center section.) Monorail cameras are usually more flexible in this regard—front and rear independently focus.

Moving the tilt axis into the image area provides one line of preserved focus. But that line’s location will be a compromise, and will require luck for it to be right where you want to preserve focus when tilting. I have never been that lucky—I always have to refocus when tilting.

Another thing—the Cambo put the axial tilts at the mid-point, but for that to work it also has to the set back from the standard to align with the film plane/ground glass. That puts knobs in the way of sliding in film holders. Dealing with that issue requires further complexity. The Sinar P uses a curved track below the standard, so the tilt axis floats in air. Beautiful but not cheap. But the Chamonix tilts around an axis well forward of the film plane, so the line where focus is preserved is going to move all over the place as you tilt.

Rick “whose Sinar P also has asymmetric tilts” Denney

Rick, can you adjust the lens rise/fall to put the subject on that line, tilt, then return the rise/fall and refocus? Seems like that would work as the tilt angle won't have changed.

[Alan Townsend]

Rick, thanks for the lengthy and instructive response. I'm sure many following this thread will appreciate it. I will try to insert a recent image file for an example. This photo was taken a few weeks ago using a 4x5 speed graphic using arista ortho litho 3.0 and a Rogonar-S 135mm F:4.5 lens for 60 seconds at F32 with no movements. Yes, this is an enlarging lens, but my Speed Graphic is used primarily as the body of my 4x5 enlarger that I built.




This is my 8mp digital camera version of the same picture.



While building my 4x5 camera with rear swings and tilts only, I'm still using my Calumet CC401. These photos are good for illustration of a typical case where I would want to improve depth of focus and/or use a larger aperture to reduce exposure times. In this case, where the foreground is about six feet away in the lower left corner, and about 150 feet away in the upper right corner, a very small swing and tilt of the film would work very well. This is so small an adjustment, it would not be noticed at all, especially with no lines, squares, or other shapes to give a clue. If there were boxes in the photo, you would need a ruler to measure the distortion or see it for that matter. I can make this adjustment in about ten seconds and take the picture thirty seconds later. With a Deardorf style, it would be almost impossible, or take much longer. I select my lenses to barely cover the format on purpose, since I use only rear swings and tilts. This makes them cheap, small, lightweight, and simple to use. On other cameras I use both the 90mm Optar F6.6 and Optar 135mm F4.5 both of which work great on axis at F22-32. I also use my Dagor F6.6 240mm both with and without its front element for longer views. I use nothing wider than 90mm because it works for me and need nothing wider. This is heart of this problem, using ultrawide angle lenses that I avoid.

Most of my photos require no corrections at all. I did an assay recently based on prior photos, and only about 25% gain from swings and tilts, and for the most part, they are just as simple as this case. I included the digital version because it looks much better than the 4x5 which is a phone scan of a high contrast negative and hard to see. But I am trying to make this real and not textbook. I use the ortho litho occasionally for low contrast photos.

I've read the theory about pie shaped something of others, but never seen it on my ground glass. In the early 1970's I became a laser technician/holographer by happenstance and was making what is known as image plane holograms using dichromated gelatin. Here I was using a lens to make a 3-dimensional image of an object that hangs out in space behind the lens, and then record this image 3 dimensionally. The DCG plate was positioned near the center of the depth of the image plane, which is 3-dimensional although they call it a plane.

I am trying to explain why I see the image as a 3-demesional thing, while everybody else is talking about 2 dimensions. They haven't seen that, and I have. The distance formula 1/do+1/di=1/f defines where in the space behind the lens every point of the object or scene is imaged in space. There is no pie shaped anything there since we are not photographing walls or other 2-dimensional objects most of the time. Only in copy work do we have all three planes that intersect and make pie shaped things. In the real world, we are finding a slice through the space behind our lenses that comes the closest to the image points of our scene to gain an advantage in depth of field. That slice we choose corresponds with a slice out in the real world, but that slice is never a plane. It is always curved. The geometry is complicated and probably not worth discussing much more. The view camera theory is a simplification of the complex film plane geometry I try to explain. If you point your camera at a ramp that angles up the same direction as the lens, on your ground glass it will look curved up. The lens distort space in the direction of distance according to the distance formula.

Most view camera photographer are liking keeping the backs level, as you say and raising the lens to view upwardly without the so-called perspective distortion thing, so are working off axis. Then why tilt the lens forward a bit to try to improve field of view. This will cause the same type of 2-dimensional distortion we are discussing, although it may be small enough to not be a problem. It's that simple. That tilt can easily take you off the coverage of the lens if not done carefully. If you want this perfect form of perspective free photograph, your depth of field improvement will be greatly limited by that choice.

I make no effort level my back. I point in any direction I want. No boxes, no buildings, no mankind and his aversion to correcting perspective distortion that he created through his architecture.

Regards

[rdenney]

There are all sorts of tricks, and all of them work for those who understand the concepts. For those who are limited by the method they learned and don’t get the concepts, their choices will be more limited.

I recall from many years ago a battle on this forum over whether a tilt-shift lens on a fixed-body camera could replicate both front and rear movements at least within its narrow working envelope. Those who understood the concepts realized they could, at the expense of convenience and with acknowledged range-of-motion limitations. Meaning: rear movements could be mimicked up to a point. Some in that debate held that without explicit rear movements, whole categories of effects were unavailable. They couldn’t translate their experience to such different equipment.

Rick “whatever gets the job done” Denney

[rdenney]

Alan, if one needs to tilt the back of a camera with no rear movements, one simply aims the camera to put the film plane where it is needed and then shifts and tilts the front lens as necessary. All motion can be described by a single translation and rotation, though the machinery will differ radically.

The limitations of image circle is a separate constraint requiring a separate compromise.

If the rear film planes in your two images are not coplanar, the perspective projection will be different. If the tilt is slight enough, you may not notice it or it may be negligible. But some subjects will be more demanding than others. I chose a demanding example for a reason. I spent considerable time aligning the rear standard to exactly align the subject lines I wanted to align. Subsequently tilting the back to adjust the focus plane would have upset that. But then I brought along a Super Angulon—had I been using a 90mm Optar, the image wouldn’t have been possible from that position and projection. You’ll note that both tilt/swing AND a tiny aperture were required.

Rick “everything has perspective but how it’s projected isn’t always part of the visualization” Denney

[rdenney]

By the way, the pie shape is the envelope, not the subject. But you knew that.

Be careful about joining a forum and a week later instructing its long-standing residents that only you know things.

Rick “word to the wise” Denney

[darr]

Why would they set asymmetrical tilt up on the rear?
https://www.chamonixviewcamera.com/cameras/45h1

Let's say you want to minimize the foreground and enlarge the background in your photo.
Here you would use the rear standard to change the lens geometry by exaggerating the background but minimizing the foreground.
You would tilt the top of the ground glass in, causing the bottom (top of your image) to enlarge, and the bottom of your image will be minimized.
Depending upon how much you what to reshape your image top and bottom depends on how much you tilt.
In a situation like that, I would forget about A-tilts, design the image via the rear tilt I want and use the front tilt to tidy up focus.

To answer your question, since rear tilt can be a powerful tool for changing compositional elements, it makes good sense to be able to focus on the front when needed.

Using rear tilt changes the lens geometry and is a powerful tool large format cameras offer to change the relationship between the foreground and background.
That means it can be useful when designing an image, not just photographing what is there, but having a tool to emphasize and minimize.
The image Mark Sawyer posted earlier of how the geometry of the lens changes with rear tilt speaks volumes about what changes with rear tilting.

I had an Ebony 45SU years ago, and it had A-tilts. It is a nice feature, but not one I use in the landscape.
But you might like having that feature, and nothing wrong with that. I did not use them often enough to justify my camera model's extra cost and weight.

Talking about this online can be too abstract for some readers, so I searched for a YouTube video and found one that I think does a great job explaining and showing:
Main Topic Starts at 1:37 if it does not start there automatically.

[Alan Townsend]

Rick,



Steve Sherman does a drastic depth of field correction in this video using only back swings and tilts, of course along with a teeny aperture. I am not the only one that does this. In his architectual photography, he works differently.

I am a very ignorant person who always seeks to learn more. I have a pretty good idea of what I know versus what I don't know. I believe I have a unique perspective on large format photography from my experience (as do all), so was trying to share some knowledge, not ruffle any feathers. Many differences between photographers using large format are due to the perspectives each of us has that others don't. This is perspective distortion that needs correction.

[Ulophot]

Welcome again, Alan. Let us join in our various ways in pursuing, discovering, and engaging in fruitful dialogue. We all love photography.

[Alan Klein]

I have not used a camera with asymmetric rear tilt, so I may have this wrong (please correct me if I am). My understanding is the rear tilts around an area 1/3 of the way up the back. This allows you to focus on that line and tilt the back until the areas above and below are in focus. This is an improvement over the base tilt where you need to refocus after each tilt change to see if you got it right. That hassle is why I use front tilt on my Chamonix N1.

How do you like the H1?

I got the H1 because I don't hike and don't need a foldable camera like the F2. So, often I can keep the same lens on the camera ready to be shot on the next outing with no assembly time.

The rear asymmetrical tilt works fine if the focus point is on the asymmetrical line. If it's not, you have to do a rise or fall on the front standard to move the line to the focus point. Then return the standard. So it may be easier in those cases to just use the traditional front tilt procedure with a few iterations of focusing.