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Old Jul 18, 2005, 5:19 PM   #8
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geriatric wrote:
Actually the DOF has nothing to do with the sensor. It is all taken care of in the lens.For example ( HD = FL^2/(A*CofC)/1000) This is before the image gets to the sensor.All the sensor does is too crop the shot. If anyone has MS EXCEL on their PC I can send them a full DOF chart for meters and feet. Just send me your email address.
Not true.

COC is closely bound up with format and is not determined "in the lens". Assuming a constant print size the crop DOES change the DOF.

Consider for example:
APS-C format COC = 0.019 mm
35mm format COC = 0.03 mm
645 format COC = 0.045 mm

There is no difference between a piece of film and a sensor of the same size however.

For a more complete set of DOF equations see:

For a COC calculator:

And as a simple test try the DOF calculator:

e.g. 50mm lens, f2.8, 10m from subject, 5x7 print, 35mm film => DOF = 7.62 m
e.g. 50mm lens, f2.8, 10m from subject, 5x7 print, APS-C sensor => DOF = 4.48 m

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