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Quote Originally Posted by iND


but for the same DISTANCE FROM THE SUBJECT is the DOF not the same for FF and CROP

No it's not


In the chart John provided you can test these yoruself


The only correlation I see is that if you have a 100mm lens on the 7D and 5D II, and you are 100' away from the subject with the 5D II and 160' from the subject with the 7D, the DOF difference between the two is the 7D is 1.6.


This ratio doesn't really work very well for other scenarios, say a 7D at 100mm and the 5D II at 160mm, both have the same framing but the DOF doesn't match the 1.6 crop.


If your at the same distance, with the same lens your DOF is significantly diffrent from the 7D and the 5D II. The ratio isn't 1.6 on it either.