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Message: <blockquote data-quote="Surveyor" data-source="post: 1354555" data-attributes="member: 50720">As far as I have been able to estimate, the maximum depth of field occurs with no aberrations and is constant among binoculars with the same magnification if we limit the boundaries to the instrument itself, i.e. stop the comparisons at the exit pupil.  As Henry, Edz, Ed and others have pointed out, any aberration that increases the blur/distortion will act to limit the DOF (the COC or blur ratio reaches it’s limits faster). As to the terms Depth of Field and Depth of Focus, my understanding of these terms is: Depth of Field is the distance between the limits of the defined blur in object space (the actual field measurements). The Depth of Focus may be regarded as the depth of field in image space. It gives the margin around the focal plane (i.e. exit pupil or the plane of exact focus, where the eye/film/detector is supposed to be) where the image blur is smaller than the prescribed blur diameter. Precisely half of the depth of focus is in front of the focal plane, and half of it in rear. See the attached calculated cross section of a focal point. Best,Ron</blockquote>