Outdoorville original editorial · updated November 14, 2026 · illustrative field photography
Start with the distance and stability
The first number is magnification and the second is objective diameter in millimeters. An 8×42 example magnifies eight times and has 42 mm objectives; these numbers do not establish optical quality.
Try field of view and eye relief
Compare field-of-view figures at the same reference distance. If you wear glasses, check usable eye relief and adjustable eyecups in person when possible.
Compare size with actual carry time
Larger objectives can add bulk and weight. For a long walk, compare listed weight, neck-strap comfort and close-focus requirements as well as magnification.
Worked choice
For scanning moving birds, a wider field and steady image may be more useful than extra magnification. For a fixed distant view, support and image detail may change the balance.