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Micro 4/3rds vs. Full Frame

Started 10 months ago | Questions thread
AeroPhotographer Regular Member • Posts: 462
Re: Micro 4/3rds vs. Full Frame

It's common to say that small sensors have greater DOF.  That's usually so, but to be precise, the sensor size is not the reason.  The greater DOF comes from the shorter focal length lens.

For macro work, you can convert focal length and distance (from camera to subject) into magnification.

DOF = k * f# (1 + M) / M^2       M=Magnification

f# is the number you set on the lens.  The (1+M) term corrects for the effective f number.  So for example at 1x, the effective f number doubles and (1+1) = 2, which corrects for this.

k depends on how much blur you tolerate, but k=.02 is pretty reasonable when DOF = millimeters.

This formula is correct regardless of sensor size or lens focal length.  But small sensors allow lower magnification because the pixel spacing is smaller.  And lower magnification  results in greater DOF.

Alan

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