BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="Atomic Chicken" data-source="post: 412061" data-attributes="member: 9786">Greetings!Thanks to everyone for your kind replies to my original thread.  I have a few replies to the responses so far, hopefully this will clear up a few things.First off, this series of tests was done under VERY carefully controlled viewing and lighting conditions, with a pair of 75 watt light bulbs placed to the two sides of the test chart and complete shielded in the direction of the binoculars in order to avoid flaring conditions.  Also, the area the test tripod was located was kept fairly dark, in order to increase pupil diameter and avoid artificial "field stop" eye conditions.Second... and this is very important... something I forgot to mention in the original post.  When determining the smallest square of parallel lines that could be resolved, the binoculars were re-aimed so that the square in question, then the next smaller square, etc. were placed in the exact center of the field of view.  This was repeated until it was impossible to distinguish individual lines, at which point the next higher square was taken as the resolution limit.  This was done in order to avoid "edge effects" from skewing the results... the resulting figures all reflect the central resolution capabilities of the binoculars in question.Finally, as to the several postings related to the H vs. V results and the contention that it is somehow my visual accuity at that particular moment that was skewing the results toward an unbalanced H vs. V resolution, I have this to say.  The H and V resolutions were determined VERY carefully, sometimes taking over 1 minute on each of the two measurements to make ABSOLUTELY CERTAIN that the two readings were accurate.  Some binoculars have equal resolutions in both directions, while others are DEFINITELY asymetrical in horizontal vs. vertical resolution.  I attribute this to one of two possible causes:  (1) imperfect optical alignment between the two axis, or (2) prism imperfections during image correction.  The one thing I am absolutely CERTAIN of with regard to these measurements is that they are NOT a result of my eyesight (which is as close to perfect as I believe is possible for a human, I have never required glasses and have always been able to see distant objects better than anyone I was with at the time).  I do not have astigmatism of any sort, and probably spend about 1/4 of my waking hours looking through optics of some kind - being a birdwatcher, astronomer, and scoped precision rifle shooter.  I believe that the results given are accurate reflections of the optics being evaluated, at least for the particular specimens that I examined.Finally, I would like to say that Elkcub is correct in stating that my intention with regards to these tests is to determine the "aided acuity" or in my own terms "real-world assisted performance" of the binoculars in question - I have no interest in using boosters, doublers, or other optical assistance that will NOT be used in the field when actually watching birds with the binoculars in question.  I am doing this series of experiements with the SOLE purpose of comparing binoculars performance under actual  viewing conditions - I am not interested in the ultimate optical performance of the test specimens but rather how well the instruments perform when used normally (with nothing between the eyepiece and the eye).Thanks to everyone for the great feedback... I look forward to further input and future tests!Best wishes,Bawko</blockquote>

Verification