I'm trying to understand the math/science elements that affect my ability to effectively use binoculars in low light. It's like trying to teach a horse to add. He can stamp his hoof and amaze people, but he really isn't adding anything. So here goes. I understand that as we get older, we lose some of our low light seeing ability. I've seen this expressed in the exit pupil. A young person will be able to open the pupil to 7mm, where an old guy like me can likely only reach 5mm. This makes sense. So, here is where it gets fuzzy. Does this mean that a pair of say 7x50 binoculars would have the same Limited magnitude for me that a 7x35 would? May my eyes theoretically not be able to utilize the extra exit pupil size afforded in the 7x50's, right? If this is correct, why is it that limited magnitude is listed for a scope based on objective size and not pupil size that is a function of the eyepiece relation to the focal ratio? Allow me to restate the question this way: Is there a limit to what my eyes will digest no matter what size scope or binoculars I use? Is it possible that my eyes could perceive no more detail in an 8" compared to a 10", any more than a dog trying to perceive the color red?