Exit pupil accuracy....
Posted 06 February 2013 - 09:03 PM
Posted 06 February 2013 - 09:50 PM
Older models and some lower end binos may use BK-7 glass instead and they will show darker chords around the exit pupil that make it look diamond shaped. Many older 7x35s from the '50s and '60s use BK-7 glass.
Longer focal ratio optics like giant astro binoculars and spotting scopes can do just fine with BK-7 prisms.
Posted 06 February 2013 - 10:06 PM
Posted 06 February 2013 - 11:36 PM
And the shape of the exit pupil varies over the range of angles it can be seen from behind the eyepiece.
In practice, slight non-circularity of the exit pupil is of no real consequence as long as other aspects of performance are not suffering.
Posted 07 February 2013 - 12:16 AM
Posted 07 February 2013 - 09:37 AM
Posted 07 February 2013 - 09:48 AM