How to Choose Binoculars: Specs Explained
How to choose binoculars: magnification, objective size, exit pupil, field of view, eye relief and coatings explained in plain English, with picks for each use.
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The short answer
To choose binoculars, start with magnification and objective size: 8×42 suits most birders and hunters, 10×42 suits open country, and 8×32 suits travel. Then check field of view, eye relief (15mm+ for glasses), close focus, waterproofing and glass quality (ED or HD glass, phase coatings). Finally, set a budget tier and pick a brand with a strong warranty.
Our top picks
- Best first all-rounder: Vortex Diamondback HD 8×42 — wide view and a no-fault lifetime warranty. Check price on Amazon
- Best mid-range all-rounder: Nikon Monarch M7 8×42 — ED glass and a wide field of view. Check price on Amazon
- Best for open country: Vortex Viper HD 10×42 — more reach with strong contrast. Check price on Amazon
- Best compact: Nikon Monarch M7 8×30 — light enough to carry everywhere. Check price on Amazon
| Spec | What it means | What to look for |
|---|---|---|
| Magnification (8x, 10x) | How much closer things look | 8x for most uses; 10x for open country |
| Objective size (32, 42mm) | Front lens diameter; affects brightness and size | 42mm all-round; 30–32mm for travel |
| Exit pupil | Objective divided by magnification | 4mm+ for general use; 5mm+ for low light |
| Field of view | Width of the scene you see | Wider makes finding subjects easier |
| Eye relief | Distance your eye can sit back and see the full view | 15mm+ if you wear glasses |
| Close focus | Nearest distance that can be sharp | Under about 2 m for butterflies and insects |
| Glass and coatings | Affect sharpness, color and contrast | ED/HD glass, fully multi-coated, phase-corrected |
| Waterproofing | Sealed and gas-purged body | Clearly stated waterproof and fogproof |
How we built this guide
This guide is based on manufacturer specifications, published optical references, and long-term owner reports from birders, hunters and travelers. We did not perform hands-on tests for this article. The goal is to help you read a spec sheet and match it to how you actually use binoculars.
What do the numbers on binoculars mean?
The first number is magnification; the second is the front lens size in millimeters. So 8×42 means eight times closer with 42mm lenses.
More magnification brings subjects closer but makes the view darker, narrower and shakier. Bigger lenses gather more light but add weight. Most people find the best balance at 8×42 or 10×42, with 8×30 or 8×32 for portability.
To find the exit pupil, divide the second number by the first. An 8×42 has a 5.25mm exit pupil, which stays bright at dawn and dusk. An 8×25 has about 3mm, which is fine in daylight but dimmer in shade.
Should you get 8x or 10x?
Get 8x if you bird in woods, want a steadier view or are new to binoculars. Get 10x if you mostly watch distant subjects in open country.
8x is easier to hold still and finds subjects faster thanks to its wider view. 10x shows more detail at distance, which helps for hawks, waterfowl or game across a valley. Our 8×42 vs 10×42 guide covers the trade-offs in depth.
What size binocular is right for you?
Choose full-size (42mm) for all-round use and low light, mid-size (30–32mm) for hiking and travel, and pocket (20–25mm) for maximum portability.
- Full-size 42mm: brightest and most forgiving, but heavier.
- Mid-size 30–32mm: great balance; see our 8×32 vs 8×42 comparison.
- Pocket 20–25mm: very portable but dimmer and fussier about eye position.
Check the Nikon Monarch M7 8×30 on Amazon →
What actually matters when buying (and what is marketing noise)?
Glass quality, coatings, field of view, eye relief and build quality change your experience the most. Big magnification claims and vague “HD” labels do not.
Specs that matter
- ED or HD glass: reduces purple and green color fringing.
- Phase-corrected coatings (roof prisms): keep contrast and sharpness high.
- Fully multi-coated lenses: more light reaches your eye.
- BaK-4 prisms: brighter, more even views than BK-7.
- Waterproof and fogproof: nitrogen or argon purged.
Marketing noise
- “Night vision” on normal binoculars.
- Zoom binoculars and huge numbers like 20×50 on cheap models.
- “Military grade” with no specific details.
- Ruby or red-coated lenses on budget models, which can distort color.
Roof prism or porro prism?
Roof prisms are slim and easier to waterproof; porro prisms give more brightness per dollar but are bulkier. Most people buying a mid-range pair choose roof prisms.
If your budget is very tight, a good porro like the Nikon Action Extreme can beat a cheap roof. See our roof vs porro guide.
Who should spend more (and who should not)?
Spend more if you go out weekly, hunt at dawn and dusk, or are sensitive to edge softness and glare. Mid-range ED binoculars are a clear step up from budget models.
Do not overspend if you go out a few times a year in daylight. A well-made budget pair, like the Vortex Diamondback HD, delivers most of the experience. Our best budget binoculars guide lists good options.
Check the Vortex Diamondback HD 8×42 on Amazon →
Watch-outs
- Glasses wearers: check eye relief before anything else.
- Kids and small faces: check minimum eye spacing (IPD).
- Warranty: buy from authorized sellers so the warranty is honored.
- Strap: plan to add a harness for long days.
- Weight: compare weights, not just sizes. Two 8x42s can differ by several ounces.
Which should you choose?
- Choose an 8×42 if you want one binocular for birding, hunting and general use.
- Choose a 10×42 if you watch open country, coasts or mountains.
- Choose an 8×30 or 8×32 if you travel, hike or want a lighter pair.
- Choose a budget pair if you are new and want to learn what you like first.
- Choose mid-range ED if you go out often and want a noticeable upgrade.
Common questions
What is the best all-round binocular size?
8×42. It balances brightness, field of view, steadiness and weight better than any other size for most people.
Is higher magnification always better?
No. Higher magnification narrows the view, darkens the image and shows more hand shake. Most people see more with a good 8x than a cheap 12x.
How much should I spend on binoculars?
It depends on how often you go out. Budget brand-name pairs are fine for occasional use; mid-range ED models suit regular birders and hunters.
What does “fully multi-coated” mean?
All air-to-glass lens surfaces have multiple anti-reflection layers. It is the highest coating grade and gives the brightest, most contrasty view.