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msgtb Aug 30, 2002 9:57 AM

Depth Of Field Charts (DOF) for D7i
There are some DOF charts on the ALLDIMAGE web site. I remember using hyperfocus to catch action shots in focus on my old Canon AE-1. It works very well. The question that I have is there are two sets of charts one being identified as FL 1/1000 the other FL 1/2000 what are these references and which is the correct chart to use. Everyone who shoots fast action should download them from the ALLDIMAGE site and try the hyperfocus technique.


padeye Aug 30, 2002 4:08 PM

Land of confusion
I think the CC: 1/2000 FL means that the circle of confusion is 1/2000 of the focal length. As I said that's my guess, I could be wrong.

If you know what circle of confusion means that makes sense, if not read on.

Focus is defined as reproducing a point source of light as a point on the film plane. As you go out of focus the point grows into a circle. If the circle is small enough it's still considered to be in focus for practical pusposes. Once the point grows larger than defined COF you are outside the depth of field.

As you can see COF is somewhat arbitrary and effected by the size of the film plane and how far it will be magnified at final output. You might run into trouble defining the same COF for digital as you would for film. IMHO COF definitions for digital should take pixel pitch into account. I don't agree with defining it as a fraction of focal length as that would allow a bigger COF at telephoto. FWIW for 35mm film it's often defined as 0.03mm while Zeiss and Sinar use a 1/1730th of the film frame diagonal.

[Edited on 8-30-2002 by padeye]

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