DSLR cameras are the most affordable digital capture device, which can meet high standards for image quality. In order to use them in a novel application like large format digital capture, the inherent design of the DSLR camera body imposes some constraints.

The figure above illustrates two key parameters that are affected by the design of the DSLR body. The focal plane where the digital sensor is located is recessed inside the mirror box cavity of the DSLR camera.

1. In order for a large format lens to focus on the sensor, it needs to satisfy these two constraints. The rear element of the lens needs to be far enough from the focal plane, such that it does not interfere with the DSLR body.

2. In order for the image to be captured by the sensor, the angle of the light from the exit pupil of the large format lens should not exceed the angle A ( identified as a half angle (A/2) ) in the figure.

In addition to these two constraints the large format camera imposes some constraints as well.

The minimum bellows draw of the large format camera, combined with a recessed lens board sets a limit on how close the lens can be brought to the focal plane. This amount is specific to each large format camera. Most often it is possible to focus a 150mm lens without a recessed lens board, and a 135mm lens with a recessed lens board.

With a very compact View Camera body, it is possible to focus a compact 90mm lens, without having the rear element of the lens interfere with the SB-01 adapter. The adapter supports an angle of view of 68 degrees, which allows good coverage from the 90mm lens in this extreme configuration.