I just tried it here at home, standing in front of the camera in the dark and triggering the exposure with the self-timer. The biggest problem was focus (sound familiar, fellow astro-imagers?). While I understand that it takes a long time to become fully dark adapted would it be safe to say that it only takes a few seconds for the pupil to expand to maximum size once exposed to dark? That's to say, once positioned in front of the camera is there any need to wait more than a few seconds after turning off the lights to take the picture? Carpe Noctem! patrick On 21 Jul 2010, at 01:49, Patrick Wiggins wrote:
Ah, good idea. Maybe we could have a "pupil measuring session" during a star party at SPOC where instead of using a mirror we could go in the SPOC garage and have someone take pictures of those wishing to be measured.
BTW, isn't 7.2mm a tad on the large size?
patrick
On 21 Jul 2010, at 01:37, Kim 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