The FOCUS always changes with distance to the target. However, if the observer sets the diopter adjustment when RELAXED (having learned to stare) that setting should remain the same throughout the observing session. The diopter setting is to compensate for the DIFFERENCE in the dioptric strength of your eyes and need not be fiddled with as that difference should remain the same whether your target is 50 feet or 5,000 yards away. :cat:
Of course I agree fully with you.
The diopter settings are indeed needed to compensate for the differences between right and left eyes , and once properly set SHOULD remain constant for that particular person for any particular viewing session.
But eyes get tired and sometimes one eye will tire more than the other depending on any particular viewing condition , I know that mine do.
But I agree , once set up properly the diopter settings should not change for any particular person.
But I still think that marking a binocular is not necessary.
I have indeed expressed myself very badly on this one.