"Assuming the same aperture, there are two ways to increase depth of field: 1. You can move farther back. This expands the field of view and changes the perspective (relative size of items) in the picture. You crop the resulting image to the original composition. 2. You can keep the camera in the same position and use a shorter focal length. This expands the field of view, but the perspective (relative size of items) remains unchanged. You crop the resulting image to the original composition."
This article takes these two concepts and demonstrates the results on the Nikon D2x and the Canon 1Ds Mark II.
Depth of Field - Nikon D2x vs Canon 1Ds Mark II
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