Rear Tilt - What am I Doing Wrong?

[Maris Rusis]

With base tilts the "rule" is focus for the FAR (the bottom of the ground glass) then tilt for the NEAR (the top of the ground glass). After the first try the FAR will probably need a bit of re-focus. Then the NEAR will probably need a small tilt adjustment. Just repeat the sequence with smaller and smaller adjustments until NEAR and FAR are both sharp.

With centre tilts I focus on the FAR and NEAR and note the change in extension and then set the focussing standard half way. Then tilt until the FAR comes sharp and the NEAR should be sharp too. Some minor tweaks to focus and tilt may be needed.

[David Lobato]

When I was new with 4x5 I read something that Fred Picker wrote about foreground objects appearing larger with back tilt. So I set up a scene and made Polaroid shots with rear tilt, then with front tilt. I used a monorail 4x5 camera with a 210mm lens. It took the side by side comparison to see for myself, and it does happen. If I could ever find those Polaroids lost in old boxes I'd post scans of them.

Then with the camera tilts zeroed, I made shots of round objects at the edges of the image circle, and the edges of the frame, using large amounts of shift. Round objects took on egg shapes in the Polaroids. I had read about that as well. These exercises have helped me a lot for shooting LF photos. I think the OP was wanting a similar lesson on using back tilt.

[Doremus Scudder]

Don,

Despite what a couple of people here have said, the effect of tilting the back is easy to see on the ground glass. It may not be as much as you are expecting, but, basically, the ground glass is WYSIWYG.

The effects of tilting are familiar to anyone who uses a projector for presentations. The farther the screen is from the projector, the larger the image will be. And, if the screen is not perpendicular to the line of projection, there will be keystoning, because one part of the screen is farther from the projector than another. Modern digital projectors have keystoning correction built in, but the old-fashioned way of fixing this was to tilt the screen so it was perpendicular to the line of projection.

Think of it this way: With a camera, the subject and lens together constitute the projector; the ground glass is the screen. The lens is projecting an image of the subject onto the screen, which is the ground glass. The projection comes from the lens in the shape of a cone; i.e., the closer the ground glass is to the lens, the smaller the image circle and vice-versa. So, the farther the ground glass is from the lens (i.e., the farther the screen is from the projector), the larger the image will be. This is intuitive if you've used projectors and screens much.

Now, mentally take your screen (i.e., the ground glass) and tilt it. You can easily see that when you do, the top gets closer or farther from the lens relative to the bottom. The projected image will be relatively larger for the part of the screen that is more distant from the lens and vice-versa.

Back to practicality. You set up your camera for a scene with some both foreground and distant elements in the same plane. Leave everything in zero position and frame and focus your shot. Now, ignoring focus make some rather aggressive tilts, forward and backward with the back, and observe the image on the ground glass. Sure, the top and bottom of the image will go in and out of focus, but note that the size will change. This is pretty evident. In practice, one can often do this to choose a size relationship (to a certain extent) between near and far elements of a scene and then correct the focus by tilting the lens stage in the opposite direction. Play with your camera a bit with a shortish lens and some scenes with near/far elements on the same plane (e.g., the flat ground) and you'll see right away what I'm talking about.

Best,

Doremus

[Noah A]

I guess my question now is, if the same effect can be accomplished with the front standard why is it always suggested to do it with the back? Is it because you might run out of image circle doing it with the front?

An important thing to understand is that front swings and tilts only affect the plane of focus, while rear tilts and swings affect both the plane of focus as well as the shape of the image.

So using front tilt won't really exaggerate (or minimize) the size of the the foreground subject, but what front tilt can do is allow you to get that foreground object in sharp focus while keeping focus on the background as well. You're correct that rear tilts are what you want if you wish to change the shape of the objects or their apparent spacial relationships within the frame.

You can certainly see the results of tilting on the groundglass, though perhaps it's not as dramatic as you had hoped. In the initial scenario you described, you may not have noticed the foreground object getting larger, but perhaps the background got a bit smaller? That is visible but it can be harder to notice on the groundglass.

The difference between base and axis tilts has been mentioned earlier, one easy thing to remember is that objects near the tilt axis don't change much. So for example, if your camera has axis tilts and the object in the foreground aligns closely with your tilt axis, it won't change much. But objects in front of it and in back of it will change.

You'll generally notice more dramatic effects with wider lenses, which even with no movements tend to exaggerate the size of foreground objects.

While I understand it, that linked article isn't that clear and it could be adding to your confusion. I get the feeling it was intended to appeal to DSLR users with T/S lenses. The photos at the end are misleading, since it looks like a different lens was used for the 'tilted' example and also the camera position has changed. You still need to get close to your subject to get the 'looming' effect you're looking for.

Also, the camera movement examples are confusing. The first camera photo with the tilted back will get you the look you want.

The second photo is just a different way to accomplish the same thing. If your camera doesn't have rear tilt, such as a DSLR with a T/S lens, you can tilt the entire camera rearwards. That action alone gets you the shape change you're looking for. The lens drop is just used to get the framing you want and the tilt is used to get the focal plane you want.

And of course, rise, fall and shifts control the framing or composition of the photo.

The position of the camera's rail or bed really is irrelevant. When the camera back is perfectly vertical (plumb), the perspective will appear natural. Tilting it will change the shape, it doesn't matter which camera movements you use to accomplish that tilt. They're all ways to accomplish the same thing. Again, front tilt controls only focus, rear tilt controls focus as well as shape.

The third camera photo in the article is misleading. If you set up the camera that way, you'll change the plane of focus but not the shape of the image since the back is vertical.

[MAubrey]

I guess my question now is, if the same effect can be accomplished with the front standard why is it always suggested to do it with the back? Is it because you might run out of image circle doing it with the front?

Well, the image circle can play a part, depending on the lens and the image format. But much of it is efficiency of movement. To replicate it with front movements, they had to use both tilt and raising...AND hand to adjust the angle of the entire camera sitting on the tripod in order to get a comparable camera position. Its much easier to have a level tripod from the beginning and just tilt the back.

Going back and reading Ansel Adam's The Camera might be worthwhile. His discussion of movements is very practical.

[mdarnton]

I think that people get in the habit of thinking of front movements for focus adjustment, and back ones for image proportions. I don't mean they do this invariably, but as a starting point, it's a convenient model because projection distance from the lens affects image size, and tilting the back is the most direct way to change the proportions of the image across the length or width of the film. You can do the same moves in many different ways, of course, and it's interesting to map out a relationship between front and back, and subject, and think of all the possible ways to get there and the ramifications of that.

I've been personally fascinated by the order that movements were developed. For instance, the earliest cameras, and simple portrait cameras also, didn't have front swings and tilts, only back. On portraits, that means to bring both eyes into focus when one is farther, moving the back for that exaggerates foreshortening, making the near cheek, too large already, larger. You'd think they'd have figured that out and immediately gone for front movements, but nope.

[MAubrey]

I've been personally fascinated by the order that movements were developed. For instance, the earliest cameras, and simple portrait cameras also, didn't have front swings and tilts, only back. On portraits, that means to bring both eyes into focus when one is farther, moving the back for that exaggerates foreshortening, making the near cheek, too large already, larger. You'd think they'd have figured that out and immediately gone for front movements, but nope.

Perhaps image circle was the limiting factor? If you're working with a normal FL tessar, for example, your image circle is already going to constrain how much you can do with front movements, whereas back swings and tilts all stay within the image circle.

[David Lobato]

Here's a real situation with back tilt. Sometime ago I read that Ansel Adams' Mount Williamson, Sierra Nevada from Manzanar, California c. 1944 used back tilt to emphasize the foreground rocks. But reading articles on it now say that he tilted the camera forward, then tilted the back to get the right focus plane for his composition. It may be possible Adams did want the near rocks to loom larger. This may also explain why some photographers trying to re-create the scene (presumably some with, and some without, back tilt) have differing opinions on the exact location, including the camera height above the ground, of his photo.

This effect may have been unavoidable due to the lack of front tilt on wooden 8x10 cameras of that time.

[Robert Tilden]

Regarding the images you linked to, you're right in that "get-low-and-close-with-a-wide-lens" was used. You can see that the perspective has changed by looking at the relative position of the grasses in the midground and the water line.

[Kodachrome25]

An important thing to understand is that front swings and tilts only affect the plane of focus, while rear tilts and swings affect both the plane of focus as well as the shape of the image.

Yes and no...

With using front tilts and swings only you are moving the lens projection angle in relation to the film plane and if the movements are significant enough, you can hit the edge of the image circle on the film area. With just rear tilts and swings you are moving the film plane around in the image circle so while you may be changing the size of objects relative to the end of the film that has moved the most, you are for the most part, in the center of the image circle if no front movements have been made.

I found this to be important to consider when I was just using front movements and sometimes it affected image sharpness. So now I use a combination of rear and front tilts and swings to both standards to arrive at optimal image quality.

It's made a big difference in overall image sharpness if more than average movements are required.