Originally Posted by typo
It is absolutely scientifically impossible for a binocular to deliver any more light to the retina of your eye than you would see directly. As well as the magnification and field of view influencing our perception, binocular designers play psycological games with the, colour spectrum and contrast so you might think you do, but invariably the total light level will be less than seeing directly.
I bright conditions when the pupil of your eye is just 2mm a 8x16 would deliver the same target luminance as an 8x56 providing other physical parameters like the transmission spectrum were the same.
Hope that's clear.
That is not true. I have used 7x50 binoculars out on the ocean at night to find harbor entrances and could see objects with them that were impossible to see without them. Part of it was the 7x magnification but the 50mm objective lenses were also concentrating the light on the exit pupil of 7mm size which is where the "twilight" factor comes into play.
Nikon states that their Monarch 7 8x42 binos will transmit twice as much light as their Monarch 7 8x30 binos. So apples to apples the larger objectives provide more light to the viewer. Better optical coatings are not going to provide a doubling of the light transmission.
Going to a Ultravid 8x32 over Bushnell 8x42 or 7x50 is not going to provide as much light to the viewer. The Ultravid's may provide better color fidelity and greater perceived contrast but that is a different matter.
What has changed over the years is the availability of high quality compact and pocket size binoculars. In many cases users of these will still have other binoculars that are medium or large size ones with 42mm or larger objectives.
For me having a good spotting scope also means that I can get away with a lesser binocular than if I had to rely on the binoculars alone.