Stan: the 30 feet refers to depth perception. Binocular summation is not distance related.
Thanks, Doc. I understand it a bit better, but not completely, even after reading some more on the two. But, not being in the medical field, the difference is irrelevant for me.
I think I will continue using the term "depth perception" to refer to all distances, up to 30', and beyond (for the simple reason that this is how everyone in my "world" understands it), with one possible exception ...........one of my best shooting buddies says he has very poor vision in his left eye. Being right-handed he still shoots sporting clays extremely well. He complains often about not being able to determine if a target is a standard target way out there or a midi closer in (always beyond 30' however), and uses his "poor depth perception" as an excuse for missing. Next time he uses the term "depth perception", to describe what he lacks, I may just need to correct him, with a lengthy explanation. He may not be convinced, but if it distracts him sufficiently from the task at hand it might "buy me a bird or two". There's nothing quite so fun as getting in your buddy's head.
