How does the depth of field with 50mm f/1.4 compare to 85mm f/1.8 with the same framing? [duplicate]
Possible Duplicate: Is there a formula to calculate DOF? Is there an easy way to establish, on paper, which of these two lenses, shot wide open and with the same subject size in frame, ...
I am pretty clear about that DOF depends on: Focal length Aperture Distance from subject Sensor size and more (as pointed in the comment). But what is the question here is: Is there any formula ...