Quote:
Originally Posted by OzEclipse
7 x 50mm binoculars have an exit pupil of 7.1mm. If you are 15 years old, that's great. But if you are older, your maximum pupil dilation will limit the performance. Multiply the magnification by your pupil dilation to get the maximum aperture.
40 yo, you'll only get the light from about 42mm of aperture [7x6mm]
50 yo, you'll only get the light from about 38mm of aperture [7x5.5mm]
60 yo, you'll only get the light from about 35mm of aperture [7x5mm]
In a dark sky under fully dark adapted conditions and depending upon your age, a pair of 10x50 should transmit much more light to you eyes than the 7 x 50's.
I recently went through this exercise, selling a pair of 9x63 Orion binoculars with excellent optics to someone 20 years younger than me because my eyes were only extracting
9 x 4.8mm = 43mm equivalent aperture worth of light. I confirmed this observationally the view being near identical to a pair of 10x42mm binoculars.
I then purchased a pair of 15 x70mm Celestron Skymaster Pro binos and the sky exploded with light.
Joe
|
Cheers Joe, very informative post.