Some details on choosing a binocular. The 10x70mm Harbor Frieght binos aren't a bad binocular, especially at the $40 price- but you need to know a bit about yourself before you spend your money. Specifically, how wide will your pupils open at night? If your pupils only open to 5mm, then about half the light-gathering power of the 10x70mm binos is going to waste. Your eye won't open enough to accommodate the entire Airy disk of the bino. If your pupils open to 6mm, then you can use about 75% of what the 10x70mm offers. Binocular model exit pupil dia (approx.) 10x50mm 5mm 10x70mm 7mm 11x70mm 6.4mm 15x70mm 4.7mm 20x80mm 4mm 25x100mm 4mm Knowing your dark-adapted pupil diameter will help you choose the best binocular for your own eyes. S&T used to sell a pupil gauge, and I think it was printed in a monthly issue some years ago. I was unable to find it on Sky Publishing's on-line catalog today, however. If someone can search for the issue it was published in and post it, I'd sure appreciate it. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Chuck Hards wrote:
S&T used to sell a pupil gauge, and I think it was printed in a monthly issue some years ago. I was unable to find it on Sky Publishing's on-line catalog today, however. If someone can search for the issue it was published in and post it, I'd sure appreciate it.
No luck with searching S&T's on line archive either. There were mentions of the gauge but no articles on the gauge itself. Unless someone has made off with it my S&T pupil gauge is still over at SPOC in the Harmons control room bookshelf. Star party this coming Saturday so maybe we can use it then. pw
Thanks, Patrick. It should be straightforward to make one, either by laying it out by hand, or printing one using the computer. In either case, one must take care to punch the pinholes at precisely the correct spacing. The more precise the gauge, the more accurately one can judge their pupil diameter. If you find yours at SPOC, perhaps you can scan it? --- Patrick Wiggins <paw@wirelessbeehive.com> wrote:
Chuck Hards wrote:
S&T used to sell a pupil gauge, and I think it was printed in a monthly issue some years ago. I was unable to find it on Sky Publishing's on-line catalog today, however. If someone can search for the issue it was published in and post it, I'd sure appreciate it.
No luck with searching S&T's on line archive either. There were mentions of the gauge but no articles on the gauge itself.
Unless someone has made off with it my S&T pupil gauge is still over at SPOC in the Harmons control room bookshelf. Star party this coming Saturday so maybe we can use it then.
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I used to work with a young woman who had large, rather attractive eyes, who told me she had to wait to get lasik surgery because her pupils fully dialated were over 9mm (early lasers apparently could not cover that much area). Talk about jealous! Last time I measured mine a few years ago (Mark Dakins had a cardboard gauge) I was about 5.5mm. Isn't it true that as you age it tends to get smaller over time? --- Chuck Hards <chuckhards@yahoo.com> wrote:
Thanks, Patrick.
It should be straightforward to make one, either by laying it out by hand, or printing one using the computer. In either case, one must take care to punch the pinholes at precisely the correct spacing. The more precise the gauge, the more accurately one can judge their pupil diameter.
If you find yours at SPOC, perhaps you can scan it?
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A diminishing pupil diameter with age is the trend, although by no means does it happen to absolutely everyone- thus the need for the gauge. There is no substitute for good genes! I'm glad you brought up lasik. Astronomers should consider the procedure carefully, since there have been cases where night-vision has been affected on idividuals with pupils opening to just over 5mm. I imagine much of this is due to individual variations in eye dimensions, perhaps also related to the skill of the opthamologist. Isn't the latest variation computer-controlled? If it helps, Rich, think of it this way: The older you get, the more efficient your eyes get, so the fewer photons you need to achieve the same level of sensitivity... ;o) --- Richard Tenney <retenney@yahoo.com> wrote:
I used to work with a young woman who had large, rather attractive eyes, who told me she had to wait to get lasik surgery because her pupils fully dialated were over 9mm (early lasers apparently could not cover that much area). Talk about jealous! Last time I measured mine a few years ago (Mark Dakins had a cardboard gauge) I was about 5.5mm. Isn't it true that as you age it tends to get smaller over time?
--- Chuck Hards <chuckhards@yahoo.com> wrote:
Thanks, Patrick.
It should be straightforward to make one, either by laying it out by hand, or printing one using the computer. In either case, one must take care to punch the pinholes at precisely the correct spacing. The more precise the gauge, the more accurately one can judge their pupil diameter.
If you find yours at SPOC, perhaps you can scan it?
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participants (3)
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Chuck Hards -
Patrick Wiggins -
Richard Tenney