> You all have me wondering what my dark adapted exit pupil
> size is. Is there a simple way to figure this out ... ?
Yes, especially if you are nearsighted
First, though, you should understand the physiology of your eye and
its image forming capabiliies. Eyes are pretty poor imagers: recall they
are made mostly out of jello. I ran some experiments in college, with
my eyes dialated to over ten mm. The aberrations, especially chromatic,
were pretty severe near the edges. So even if your eyes do open to
7 or 8mm, that last mm may be not worth it.
Second, to measure your pupil.
Suppose you take an occluding object, say a piece of paper. If you
look at a distant point source and slowly move it from above your eye
to below your eye, then it will cover all of your pupil, and hence block
your view of the source, if and only if it is as wide as your pupil.
If not, you will be able to "see under it" and then "see over it".
So, you cut a long piece of paper into a wedge, say 3mm wide at one
end and 12mm wide at the other. Do the above experiment, after you
are adapted, and find the spot along the wedge that just blocks the object.
Measure the wedge at that point and you have your pupil diameter.
The above is much easier to do if you are nearsighted (or mucho farsighted)
because then without glasses you see a round blob that matches your pupil,
and you can watch the wedge occluding the blob and it is simple to
identify the "just blocks all" point.
Bob Ayers
---
Aug 25, 2008: TAC Web Page Updated http://observers.org/TAC.cgi/Announcements/
CalStar - Sept 25-27, BYO Party! http://www.sjaa.net/calstar/
TAC mailing list - join or leave here: http://seds.org/mailman/listinfo/sf-bay-tac
Received on Wed Aug 27 16:29:39 2008
|
|
|
|
|
|
|
|
|
Observing Sites |