Patrick et all, Here is from Sky&Telescope last page of the article in the link: http://www.skyandtelescope.com/howto/basics/3304201.html It's easy to find your pupil diameter and observe how it changes in varying light. For a quick test, hold a pencil vertically just in front of your eye, resting it against your cheek and eyebrow. Close the other eye. A standard pencil is about 7 mm in diameter. Against bright light you'll see a fuzzy fringe surrounding an opaque core. Block most of the light from view by cupping your hands, and watch the core narrow. If the core thins away completely in dim light, so that you can see a little light right through its center, your pupil has enlarged beyond 7 mm. A better method is to use a pair of small slits in an opaque sheet with their inner edges separated by a measured distance. Look through the pair of slits while holding the paper against your eyebrow and cheek. (The holes should be about 14 mm in front of your eye, but this is not critical unless you are strongly nearsighted or farsighted and aren't wearing contact lenses.) You'll see two dim disks of light. If their edges barely touch, your pupil diameter equals the separation of the holes. The pupil does most of its dilating in the first second or two after you enter the dark, but it takes a few minutes to reach its absolute maximum size. Pupil dilation should not be confused with true dark adaptation, a chemical process that happens more slowly in the retina. Of course if you get an eye exam, just ask the doctor or assistant to measure them . . . I did last spring so I got the info. On Wed, Jul 21, 2010 at 1:37 AM, Kim <kimharch@cut.net> wrote:
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size.
Last time I did this I measured my pupil to be about 7.2 mm in diameter.
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, July 21, 2010 12:26 AM To: utah astronomy utah astronomy listserve Subject: [Utah-astronomy] Measuring pupil size
During last evening's SLAS meeting Prez. Dave covered basic telescope math including several mentions of various optical systems' exit pupils (basically diameter/power).
During Advanced Training that followed I asked around about how to go about measuring the size of the eye's pupil.
Dave and I both remembered the pupil measurement device Edmund used to sell but Dave noted it didn't do much good since it had to be used with the lights on.
Anyone here have any ideas on how to measure pupil diameter under low-light conditions?
Thanks,
patrick
p.s. As was noted in the meeting, Dave's talk was a historic first in that it was the first time he had ever given a presentation with a computer and *NO* slide projector. Could this possibly mean SLAS's aged and long suffering slide projector is now going to join the Mickey Mouse telescope in well deserved retirement?!? _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
-- Jay Eads