Setting Up a Shot with a Tilt Shift Lens
A tilt shift lens is designed to give photographers greater control over their images, by being able to move their lens to suit the laws of optics, while keeping the camera body in a fixed position. This allows the ability to either correct perspective problems or accentuate them for artistic purposes.
Step 1: Placing the Camera and Deciding on the Frame
The first step in setting up any shot is determining where the camera will be placed and what the frame will be. You must look at the subject and determine what angle you want your photograph to be viewed from. Once you are happy, you will determine the frame by choosing a lens. The size of the lens will determine the size of the frame.
Please note that tilt shift lenses come in fixed sizes. The only way to go from a wide shot to a close up with an 85mm lens is to physically move the camera closer to the subject.
Step 2: Adjusting the Shift
According to the laws of optics, the subject plane needs to be parallel with the image plane of the camera in order for parallel lines on the subject to remain parallel in the photograph. For example, if you're shooting a tall building, then the odds are pretty good that the subject plane and image plane will not be parallel. This will then create the perspective that the lines in the building are going to converge when in reality they are parallel. Adjusting the shift of the lens can correct this perspective problem. You can move the lens without moving the camera in order to make the subject and image planes parallel to each other.
You can also adjust the tilt to accentuate your perspective problems for artistic reasons. You can distort the subject to make it look like it is about to fall over, when in reality that's not the case.
Step 3: Adjusting the Tilt
Adjusting the lens' tilt will have a direct impact on the images depth of field. In an ordinary lens, the image plane, lens plane and subject plane are all parallel to each other, which results with all the objects in sharp focus being the same distance from the lens on an imaginary straight line parallel to the lens. When you alter the tilt, you are moving the imaginary focus line so that it is no longer parallel to the image plane. As a result, an object that is ten feet away from the lens and an object that is twenty five feet away can both be in sharp focus, as long as they rest on an imaginary line parallel to tilted angle.