For finding things in the field, you need fairly bright binoculars. The navies of the world generally use 7x50 binoculars on their ships. These offer a 7.1mm exit pupil and gather all the light young eyes can use. They also offer a good field of view and as much magnification as is practical from a moving vessel. However, they are comparatively heavy and bulky. This is not a problem for a fisherman operating from a boat and 7x50 marine binoculars are the first choice for the salt water fisherman. However, the hunter needs something more compact.
For field applications a 4mm to 5mm exit pupil is usually satisfactory and 6x30, 7x35, 8x30, or 9x35 binoculars are probably the most useful compromise for hunting. They are bright enough to allow the observer to see into shadowed areas, or in dim light, and compact enough to not be an excessive burden to carry. Higher power binoculars are hard to hold steady without external support and objective lenses of 40mm or larger tend to make for heavy and bulky binoculars that are a burden to carry.
The woods hunter will be well served by a glass with a generous field of view, like a 6x30. The mountain hunter will probably favor higher power, since he will use them to spot game at greater distances. 8x30 or 9x35 binoculars will do well. A pair of the common 7x35 size binoculars is probably about as good for all-around field use as any. Whatever magnification best fits your needs, be sure to buy top quality binoculars and you will not be disappointed.
