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Message: <blockquote data-quote="jcbouget" data-source="post: 1532429" data-attributes="member: 17837">I have finally tried to do some numerical applications of the formula, with several values I have found on the web, and my previous knowledge.I won’t detail the calculations, but changing the apparent field of view from 50° to 65° barely modifies the pupil diameter, even in low light situations. For a typical interior of an office, lit by a lamp, the pupil increases from 3.08 mm to 3.28 mm. This change is obviously too small to have a significant impact on DOF.However, I think this formula must be taken with caution, because a rapid check of my pupils in a similar situation shows that their diameter is about 4 or 5 mm. Furthermore the text says that the formula is valid for an area up to 25° only.These measurements are very interesting indeed.A typical overcast day is about 4000 lux. For this illumination and beyond, the pupil already reaches its smallest diameter, around 2.5 mm. The typical illumination over a desk in an office is 300 lux. At this illumination, the pupil is about 4 mm, which seems realistic.So a significant change in the pupil diameter requires a huge change in illumination. Here the consequence is the same : the differences in AFOV between binoculars are too small to create perceptible differences in DOF.This is not very surprising, but it’s nice to have a solid answer.Jean-Charles</blockquote>