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I imagine the post below has been previously discussed.

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No I would imagine that post to which you linked has not been discussed, although there are members of this board that took part in that discussion.

BTW, are you quoting your own posts from that thread? If not you need to credit her.

Also I'll point out that while numerous other factor were mentioned in that thread, it evolved it seems to be mostly about coating transmissions ["the number of lens surfaces and the quality and completeness of the multicoatings are the dominant factors."]. Worth mention, the individual you quoted, several times posts errors in miscalculations of total transmission based on the transmission of a single coated surface. It seems she neglects the compounding factor for number of surfaces and instead simply adds.

"On the other hand this seems to account for statements in places like CloudyNights.com where they claim that a multicoated 2 surface lens (cemented or not) will transmit 99+% of the light coming to it, so even with 10 surfaces there may only be 1% light loss total for the binocular system."
That statement is incorrect. there are others just like it.

What's also interesting is immediately following this mis-statement, she points to one of my articles here on CN; an article in which I know the information is not miscalculated. So not only is the coatings information miscaclutated but it is mis-referenced.

Anyway, back to my point, they are discussing coatings. This post is discussing vignette and what happens when you don't compare the entire exit pupil or what happens when you compare a portion of a larger exit pupil to a whole smaller exit pupil. I think the only person in that thread to recognize the significance of that concept may have been Henry Link where he said, "In tests using only the center 2.5mm of the binocular objective "real world" factors like optical aberrations, internal reflections and vignetting would play no significant roll in the measurements, but of course these things do effect contrast and apparent brightness for an actual observer."

So what's more important here is, while coatings and all other build aspects and aberrations are important to the brightness seen, that is not what is singled out for explaination in this thread. There are numerous other threads on each of those other topics that can be found by links through the Best Of thread. Vignette of light across the exit pupil is the basis of this explanation. Not only did no one mention that in the BF thread, but none of the manufactuter technical test data they referred to mentioned it either. Just a thought, but seems lot's of people may really be missing some pieces of the puzzle.

edz

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