To continue with my adventure into large format photography I will be stepping into the camera movements. I plan to keep this post in practical language, not technical mathematical proofs as those are plentiful on the web. I do want to dig a little into the Scheimpflug Principle and how I use it to guess-and-adjust my focus, but again, I'm not getting nerdy with it. Various large format cameras have various movements. Usually, the studio ones tend to have em all while the others have a selection. It's something to consider if you're in the market for a body. For my Chamonix 45n-2, I selected it based on all the movements on the front standard and the tilt and swing of the rear standard (no rear shift). For the style I shoot, this was meeting my demands. Some cameras will have more or less, depending. What you choose is ultimately dictated by what you're really trying to accomplish.
If you're brand new to these terms, I think a good starting place is a look at the various planes and what kinds of movements are available. If you're here just for a look into the Scheimpflug Principle, scroll down a bit.
Da Plane, Boss, Da Plane!
OK, let's dig into the three planes that are necessary to understand before jumping into the Scheimpflug Principle. The focal, film and sharp focus planes.
The front standard is where the focal (or lens) plane sits. It's comprised of a board which holds the lens and shutter and may or may not allow the movements of rise, fall, swing, tilt and shift. This is where you focus the subject through the lens onto the film, plate or ground glass.
The film plane is located at the rear standard - where the ground glass, and ultimately your film or plate resides. Like the front standard, some, none or all of these movements are available: rise, fall, swing, tilt and shift. Light is carried from the focal plane, through the bellows and focused onto the film plane.
Plane of Sharp Focus
Simply put, this is the area of your photo that you want to keep in sharp focus. If you are using a camera with no movements (think: almost any 35mm or medium format camera) the plane of sharp focus will always be parallel to your focal and film planes, as they are fixed (assuming no tilt-shift lens). Picture having a lens at f/1.4 on a close subject and that razor thin area that is in-focus, as seen to the right.
The dog's eyes, chest and front paws are in sharp focus. This "plane" rises above and below, the dog, but in front and behind this plane fades to blur. The plane of sharp focus is perfectly parallel to the angle of the camera that was taking this image.
If I wanted a non-parallel-to-my-camera plane in sharp focus (for example, the plane travels across the dog at an angle instead if up and down) then movements need to come into play. And this is the power of view cameras.
Once again, my friend Craig gave a great visualization to help "see" this plane. He sees each one as a giant sheet of glass. Everything on this sheet is in the plane of sharp focus. Anything falling in front of or behind this sheet of glass, simply is not. To make the glass "thicker" just close the aperture. To make it thin (like on the dog's eyes) just open it up!
Rise & Fall
Pictured left is "rise" on the front standard of a camera. I do not have rise/fall on the rear standard, though some cameras do. I only have rise and fall on the front standard. Rise and fall are used to keep the lens axis and film plane perpendicular. Rise is the upward while fall is downward movement of the lens on the focal or film plane. This is used to get objects in frame (tall trees, buildings, etc) without giving the appearance of them falling over. If you've taken images of tall buildings while in the city, you know exactly what I am refering to here.
For example, to the right I have an example of what happens with a fixed-plane camera framing a building from a low vantage point. Notice how the building perspective is wide at the base and narrow at the top, due to the angle of the film plane. This gets more extreme the more the angle changes between the film plane and the subject plane.
With the use of rise on a large format camera, we'd be able to take this same frame, but the lines of the building would remain parallel to each other because the subject, focal plane and film plane would all remain parallel. (image to the left).
Note: Maximum rise & fall, swing, tilt and shift are limited by the image circle of your lens.
Shift (left and right) is just like rise and fall, but works on the horizontal rather than the vertical. There are situations where you may need to use this, like when the tripod is against a building or tree and you don't have the option of nudging it over. Shift can give you that extra distance in your frame. Again, this is used to keep the film and focal planes parallel to each other and your subject.
These movements are available at both the front and rear standards on my camera. Swing can be used to correct the distortion of horizontal lines and is done by "pivoting" the lens or rear element to the left or right as seen from above. With this movement, the film plane is no longer parallel to the focal plane nor subject, allowing you to correct the horizontal lines of your subject.
For example, let's say where taking a photo of a car that's at a slight angle to the camera. If taken straight on, the left fender would have a different focal distance compared to the right. Swinging the lens brings the focal points into balance and the entire nose of the car can be in exact focus. (Alternatively, you can use it the opposite way to extremely exaggerate these perspectives).
Note: There are volumes out there on the use of swing and tilt and its effect on distortion and depth of field. I suggest Googling Merklinger and Luong for more on this.
Tilt can occur at the front or rear element in most view cameras and is basically the same thing as swing, but rather than correcting for horizontal lines, it corrects for vertical lines. The image to the left is showing tilt up (opposed to tilt down) to correct the vertical lines of the building (no fat base).
If you've used or heard of tilt-shift lenses on 35mm and medium format cameras, this is the movement they are more or less doing, though there is a ton more movement on a large format setup.
As long as your lens has the appropriate image circle*, these above movements can be used in conjunction with each other to do some pretty cool things with depth, perspective and focus planes.
*One little trick to know if you're within the limits of your image circle is to look through the four cut-out corners of your ground glass while the lens is wide open. If you can see the light in the back of the lens, then the image will be hitting your film in that corner when you expose it.
OK, so all that business above was so I could talk about this: the Sheimpflug Principle. This is where many like to talk about the crazy calculations to determine the necessary tilt to work with the desired plane of focus. I'm going to keep this simple.
When thinking about a typical fixed camera with the film plane parallel to the focus plane, your plane of sharp focus must also be parallel. The example often given is photographing a wall. If you're facing it straight on, all four corners of this wall can easily be in sharp focus, even with a thin depth of field. But if you walk to one edge of the wall and are now shooting it at an angle, only a small section (perhaps the two near corners or the two far corners) can now be in the plane of sharp focus.
To correct for this, the focus plane needs to tilt (for vertical) or swing (for horizontal) to get the 4 points on the plane of sharp focus. Without any calculations, the angle of this tilt is just shy of half the angle between the film plane and plane of sharp focus.
See the illustration to the right where the plane of sharp focus is running from my dog to a building in the distance. Imagine that line continuing until it intersects with the imaginary line of the film plane. Where those two lines cross is where a third line begins (this is called the Scheimpflug Intersection) and continues through your focal plane - and that's the angle your lens needs to be to have the dog and building in sharp focus. Again, roughly half the angle in this example.
With my few experiments, I quickly eyeball this angle, then adjust while looking at the ground glass with the mantra:
Focus on the near, tilt to the far, focus on the near, tilt to the far...
Within three adjustments, everything I want sharp is sharp.
Obviously, this is a very crude overview of the principal and something you can dive into if you're really interested. To me, it was a cool fundamental to have a base understanding of but not something I wanted to dig into more than I did. (I worked out some of the math on paper, then realized I'd never do this in the field.)
Depth of Field with Swing and Tilt
Finally, a bit on this before I cut you loose. Depth of Field (DoF) is parallel to the plane of sharp focus when using a non-movement-having camera. The distance to either side is a function of aperture, distance and lens length. Easy enough.
But when swing and tilt are thrown into the mix, the DoF is no longer parallel to the plane of sharp focus, rather, it clam shells. For this again, a picture will explain it nicely.
To the left you can see with the camera lens tilted up, the DoF along the plane of sharp focus gets more wide. When you tilt down, the opposite happens (just flip the clam shell). It's something to keep in mind, as there are many great things you can do with depth and off-center subjects.
I promise to start posting photos that go along with these movements as I get to do more with them.