How is the circle of confusion (CoC or CoF) determined?
For depth of field calculations, the circle of confusion (CoC) is the smallest acceptable amount of blur in the image plane. To determine the CoC, you must do the following: • Decide on a print (or display) size • Determine a set of viewing conditions • Decide on the amount of blur in (1) that is tolerable for an “in focus” appearance when viewed in (2) • Divide by the enlargement needed to produce (1) It’s good to understand the depth of field is not well defined without a set of viewing conditions and assumptions about what appears to be in focus. Except for the exact depth at which the camera is focused, everything in the image plane is at some smoothly varying point between perfect focus and total blur. The amount of tolerable blur in the final image determines where you make the cutoff in this continuum between blur and sharpness in the image plane. Without a set of assumptions about how we view images, there would be no way to make this cutoff since everything (except for a 0 thi
