This is an interesting thread. One of my other interests is astronomy and I use binoculars all the time - in my case a pair of Canon 10 x 30 IS image-stabilised binoculars. On the binocular forum I frequent the talk is that 7mm exit-pupil binoculars are a waste of time UNLESS you are in areas with very dark skies - which I guess would include many areas suitable for the practice of bushcraft. Although the average pupil only dilates to around 5mm, this can be extended with practice to around 6mm or more (I have an article from an old issue of Sky and Telescope where the author measured his own pupil diameter at 6.5mm and he is in his sixties).
If you are going for spotting wildlife in the dark or twilight conditions, it is best to have more aperture and a bigger exit pupil, for example 10 x 50, 7 x 50, 8 x 56, 9 x 63 etc. Many binoculars available today are aimed at birders where the median seems to be settled at 8 x 32 (ie a 4mm exit pupil) which is fine in most conditions. To many birders, it seems, even a 42mm binocular is pushing the boundaries of acceptable size.
You also have to consider other factors which I feel are beyond the scope of this thread. For example, are you likely to be using them in harsh weather? In which case some kind of water resistance would be in order. Do you wear glasses? If so, long eye-relief (the distance required between the eyeball and the eyepiece) is a must, with adjustable eyecups a distinct advantage. Are you bothered by optical defects (eg false colour, astigmatism)? Then try to afford the most expensive binoculars you can afford. This is one area where you generally get what you pay for, although the "bang per buck" drops off sharply after a certain limit and you can pay astronomical prices for top-quality optics. (pun intended
): )
Try this site:
www.betterviewdesired.com
It gives advice on optics in various price-ranges. However the best bit of advice I can give is to try as many pairs as you can to see what you like and more importantly, what you don't. Any binocular is going to be a compromise between power, compactness, suitability for different conditions, price etc. Choosing a pair of binoculars is not a simple process and I know many who agonise over this for weeks if not months. It is a decision best made not in haste, as you can easily regret it at your leisure.....
Best wishes,
Bruce
