Birdwatching.com has an article about how your pupil shrinks with age, so that (in daylight) a 20-year old's pupil will be 4.7mm, while a 60-year old's will be 3.1mm. What implications does this have for my choice of binoculars? I'm rapidly approaching 60, and have artificial lenses in my eyes (does this have any effect on anything?). I've been looking at binoculars in the 8x30/8x32 range to use in the daytime - hardly ever in the twilight. If my pupils are around 3.1mm, then I should theoretically only need an 8x25 for daytime use, but I'm still tending towards the 8x30ish for the sake of a bit more leeway in eye placement. Is this reasonable, or have I got the wrong end of the stick - or the wrong stick entirely?
Michael.
In using our eyes, more available light for the pupil won't hurt anything in normal daily use, and in fact might be advantageous. I'm older than you and I have 2 artificial lens implants. I routinely use either a Nikon 8 x 30 EII or a Leica 7 x 42 BN Trinovid as my binocular of choice. In twilight, overcast or rainy conditions the Leica is my choice and the difference in brightness over the Nikon is quite apparent. I would never use a binocular with an exit pupil of under 3.5 as my 1st choice under any condition. I don't know how wide my pupils open under dark conditions but I can see the difference in brightness between the 2 binoculars and I have no problem placing my pupils in the right alignment with their exit pupils. The same thing goes when I use the 7 x42's under very bright conditions. No problems at all there either. BTW, I was nearsighted before my cataract surgerys and as far as I'm concerned the results of the surgerys were miraculous!
Bob
I am 57 and use a Nikon SE 8x32 for bird watching. It provides plenty of light into twilight.