I agree Jim
DOF and focal length is a common misconception.
The point came home to me the other week when I was doing some calculations for a 300mm and 400mm lens. Basically I wanted to increase the DOF by using a 300mm. By the time you reduced the subject to lens distance to get the same image size as the 400mm you find you end up with the same DOF at the same apeture.
Part of the exercise was also to look at the effect a TC or an extention tube would have on DOF and again maintain the same image size.
Rob
Last edited by robski; 22-12-05 at 14:27.
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