henry link
Well-known member
Just read that long focal length telescopes have more depth of field! Guess stopping down to increase dof may also work for binoculars... Not sure how much effect the stopping down or increasing focal length by 25% has though, because in telescopes the increases in length are much larger....:smoke:
Just noticed this post. My answer above applies to telescopes as well. If the telescope's exit pupil is larger than the eye's pupil magnification is the one and only significant factor for DOF. However, if the telescope objective is stopped down so that the exit pupil is smaller than the eye's pupil the DOF will increase, not because the focal ratio of the telescope is higher, but because the focal ratio of the the eye is now higher.
Henry