Good binoculars are a lifetime purchase. Bad ones are an expensive mistake you carry every trip. Here is how to choose.
Binocular specs get thrown around without much explanation — "8x42," "exit pupil," "ED glass" — and the numbers matter a lot more than the brand name on the box. Here's what they actually mean for hunting and birdwatching in Australian conditions.
Reading the Numbers: Magnification x Objective Lens
Binoculars are specified as two numbers, like 8x42 or 10x50. The first is magnification — how many times closer the subject appears. The second is the objective lens diameter in millimetres — the front lenses that gather light.
Magnification trade-offs: Higher magnification (10x, 12x) brings distant subjects closer but narrows your field of view, amplifies hand-shake, and makes it harder to relocate a subject you've spotted with the naked eye. Lower magnification (7x, 8x) gives a wider field of view and a more stable, forgiving image, which matters more than raw magnification for most field use — especially picking up movement or relocating game or birds quickly.
Objective lens trade-offs: A larger objective lens gathers more light, which helps in low light (dawn, dusk, dense forest) but adds weight and bulk. A 42mm objective is a common, sensible middle ground for general hunting and birdwatching use. Larger 50mm+ objectives suit dedicated low-light glassing but are noticeably heavier to carry and hold steady for extended periods.
Exit Pupil: The Spec Most People Skip
Exit pupil is the objective lens diameter divided by magnification (so 8x42 gives an exit pupil of 5.25mm). It roughly indicates how bright the image will appear, particularly in low light — a larger exit pupil generally means a brighter view at dawn or dusk. This is one reason 8x42 configurations are popular for hunting: they deliver a genuinely bright image without the weight of a 50mm+ objective.
Field of View
Wider field of view makes it easier to track moving animals or birds and to relocate a subject after glancing away. It's typically listed as either an angle (in degrees) or a linear measurement (metres at 1,000m). Lower magnification generally comes with a wider field of view — another reason 8x is often favoured over 10x for hunting, where quickly acquiring and tracking a moving animal matters more than maximum reach.
Glass and Coatings: Where the Real Price Difference Comes From
Two binoculars with identical magnification and objective size can perform very differently based on glass quality and lens coatings — this is genuinely where most of the price difference in the mid-to-high end of the market comes from, rather than from magnification or size.
- ED (extra-low dispersion) or HD glass reduces chromatic aberration — the colour fringing you sometimes see around high-contrast edges (a bird against bright sky, an animal against a light background). More noticeable at higher magnification and larger objectives.
- Fully multi-coated lenses (coatings applied to all air-to-glass surfaces, not just some) transmit more light and reduce internal reflections, meaningfully improving brightness and contrast over partially coated or uncoated optics.
- Prism type — roof prism designs are more compact and rugged, and dominate the mid-to-high end of the market; porro prism designs can offer excellent optical performance at lower cost but are bulkier.
Waterproofing and Fogproofing
For genuine field use in Australian conditions — creek crossings, humidity, temperature swings between dawn and midday — look specifically for nitrogen- or argon-purged, O-ring sealed construction. This is what actually prevents internal fogging when moving between temperature extremes, not just external water resistance on the housing.
Weight and How You'll Actually Use Them
The best binoculars on paper are the wrong choice if they're too heavy to comfortably carry and hold steady for the way you actually hunt or watch. If you're doing extended glassing sessions from a fixed position, a larger, heavier pair on a harness is manageable. If you're covering ground on foot for hours, weight becomes a real factor in whether you'll actually use them consistently rather than leaving them in the pack.
What to Prioritise
For most Australian hunting and birdwatching use, 8x42 is a genuinely sensible default — a good balance of brightness, field of view, and portability. Beyond magnification and objective size, prioritise fully multi-coated optics and confirmed waterproof/fogproof construction over marginal spec differences in magnification. Where possible, look through a pair before buying rather than choosing on spec sheet alone — image brightness, sharpness at the edges, and how comfortable the eyecups feel are hard to judge from numbers.
