BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="henry link" data-source="post: 3333132" data-attributes="member: 6806">I just noticed this thread. I believe Tobias is using the same technique to make his images that I have used in the past. If so, then he is right about exit pupil and aperture having no bearing on the brightness of the images. Just now I quickly made some photos to try to demonstrate this because I think it is easier to show than to explain. The two on the left were made by pointing the camera into the eyepiece of a 7x50 binocular at full aperture and stopped down to 18mm. Notice that the exit pupils are different sizes, but the light intensity inside each is more or less equal (and would be exactly equal if I had been more careful). If done properly the smaller exit pupil would completely disappear if it were cropped out and placed at the center of the larger one, since after all, it IS the center of the larger one.The two photos on the right are the same binocular photographed through the front. Now the "aperture" is determined by the field stop of the eyepiece and, for practical purposes, the exit pupil is the size of the binocular objective lens. Once again one of these was made at the full 50mm aperture and the other with the objective stopped down to 18mm. Any small differences you see have to do with haste and sloppiness rather exit pupil size. The card behind the binocular is not perfectly evenly illuminated and the camera was handheld, so not perfectly aligned with the binocular's optical axis. Henry</blockquote>

Verification