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Message: <blockquote data-quote="typo" data-source="post: 3316321" data-attributes="member: 83808">In the strictest sense, depth of field only depends on the magnification and the objective diameter. Higher magnification, shorter DOF. However, as the pupil of the eye dilates and contracts, the effective objective diameter changes. We see a better depth of field in brighter conditions than in dim conditions.With a flat field designs, the depth of field should be pretty uniform across the didth of the view, but because the eye has higher acuity in the centre of the view than the edges it might not always seem that way. Simpler optical configurations can have field curvature. That means the focal point at the edges is closer than the centre. So if you were standing perpendiculr to a distant hedge for instance, the horizontal edges would be out of focus but the foreground between the hedge and your self might be in sharp focus. This can give a perception of greater depth of field.The width of the field of view doesn't really come in to it, but I guess altering the FOV could alter the degree of curvature but it changes other characteristics as well. So a blured edge to a view can be due to field curvature, (which I consider a positive characteristic in some situation), or to optical aberrations such as astigmatism, when the view cannot be brought to sharp focus. I am happy to  use both flat and curved field binoculars as both have their strengths, but I'm not keen on soft edges as that's redundant FOV and reduced perceived DOF.David</blockquote>

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