There have been lots of discussions about the pros and cons of various optics, these last months. And every now and then, I encountered remarks along the line of "more than 60x brings nothing in a 60mm objective scope as it appoaches the theoretical limit of resolution". Often, this info was kind of a side-note only. For my next binoculars, I still have to decide not only which brand might fit my needs best, but I also have to make up my mind whether it should (again) be a 8x32 or rather 8x42, or even 10x42. Because of weight considerations, I strongly tend to get another 8x32. I therefore wonder what I might gain by going to the heavier types. It's clear, theoretically I should gain brightness with the 8x42, and with the 10x42 it would be higher magnification but back to the brightness I would also have in the 8x32. This is all meant without regard to differences between different brands or types.
My questions, then, revolve around the following:
1) How much brighter would the 8x42 be, or rather how much benefit would I get in low light (inside of a dense forest or at dawn/dusk)? I should add here that I had very frustrating times some years ago in the Peruvian rain forest with my 8x32 Leica BAs. I simply could not discern colours sufficiently.
2) How much better would resolution be (again the question is about potential, i.e. theoretically possible gain) by switching from 32 to 42mm lenses?
3) 10x is supposed to be better than 8x under low light conditions. I am not sure why, but would this mean that I should prefer 10x42 over 8x42 in spite of a smaller exit pupil? I should add here that I often use my wife's Zeiss Victory I 10x40s. And it takes me considerably longer to "catch" the picture than with my 8x Leicas, but that extra magnification is often most welcome for raptors and shorebirds. On the other hand, I tend to lug around a scope whenever possible. But, as I said at the beginning, this thread is about the theoretically possible gains, and not about what is preferred by an individual. We have read that before in other threads, and the examples given above are therefore not meant to compare Zeiss and Leica. Thus, maybe Henry or some other knowledgable "theoretician" can provide a summary to the benefit of many of us? In the end, we'll still have to weigh for ourselves, but it might make decisions a bit easier.
Thanks, Robert
[QUOTE=Swissboy]
3) 10x is supposed to be better than 8x under low light conditions. I am not sure why, but would this mean that I should prefer 10x42 over 8x42 in spite of a smaller exit pupil? I should add here that I often use my wife's Zeiss Victory I 10x40s. And it takes me considerably longer to "catch" the picture than with my 8x Leicas, but that extra magnification is often most welcome for raptors and shorebirds. On the other hand, I tend to lug around a scope whenever possible. But, as I said at the beginning, this thread is about the theoretically possible gains, and not about what is preferred by an individual. We have read that before in other threads, and the examples given above are therefore not meant to compare Zeiss and Leica. Thus, maybe Henry or some other knowledgable "theoretician" can provide a summary to the benefit of many of us? In the end, we'll still have to weigh for ourselves, but it might make decisions a bit easier.
Thanks, Robert[/QUOTE]
Well, I'll try to say something. 10x is supposed to better than 8x in low light conditions? I didn't know that. It always seemed like the other way around to me, at least with the binos I've had.
marcus
Greetings!
Low light performance in binoculars seems to be driven by 3 main factors. These are:
#1 - Size of the objective lens
#2 - Magnification of the binocular
#3 - Lens coatings
All three of these play a part in how well you will be able to see under low light conditions.
The size of the objective lens determines how much light is being "gathered" by the front end of the binoculars. The larger the objective lens, the bigger the "window" the light is going through on it's way to your eye, so obviously with more light to start with, all other things being equal, you will have more light at the other end. However, all things are RARELY equal between the objective and eyepiece.
The lens coatings are very important. They help to minimize the amount of light that is reflected by the optics, as opposed to being transmitted through the optical system. It is quite common for a pair of uncoated or cheaply coated binoculars with large objective lenses to be outperformed by a pair of smaller objective lens binoculars with excellent coatings.
Finally, the magnification of the binocular. Contrary to what you have been told, higher magnification binoculars are typically NOT brighter, it is the other way around. The more magnification, the dimmer the binoculars - all other things being equal. I think the reason the "higher power=brighter" myth has been going on is that typically higher power binoculars start out with larger objective lenses, in order to have a decent size exit pupil at the eyepiece (the diameter of the circle of light that leaves the eyepiece on it's way to your eye). Because higher power binoculars often have very large objective lenses, they can, under many circumstances seem brigher than lower power binoculars that are using smaller objective lenses. However, if the objective lens is the same size, a 8X42 will in most dim conditions be brigher than an equivalent 10X42.
I hope this information helps...
Best wishes,
Bawko