Quick answer: In '8x42', 8 is the magnification and 42 is the front (objective) lens diameter in millimetres. For bird watching, 8x42 gives a wider, steadier view, while 10x42 shows more detail but magnifies hand shake. Compact pairs like 8x21 are lighter but dimmer.
Every pair of binoculars has two numbers on it, and those binocular numbers tell you most of what you need to know. Once you can read them, choosing a pair gets much easier.
Here's what they mean, how to choose for bird watching, travel and boating, and the honest picks from our Barska range.
In this guide
What the numbers mean
Take 10x42:
- 10 is the magnification. Things look 10 times closer.
- 42 is the diameter of each front (objective) lens in millimetres. Bigger lenses gather more light.
Divide the second number by the first and you get the exit pupil in mm (42 ÷ 10 = 4.2mm). A bigger exit pupil generally means a brighter image in low light, at dawn and dusk.
8x42 vs 10x42
- 8x gives a wider field of view and a steadier image, so it's easier to find and follow a moving bird.
- 10x shows more detail, but every wobble of your hands is magnified too.
We don't currently stock an 8x42. Our closest bird-watching options are 10x42 pairs like the Barska Lucid View 10x42 and the waterproof Barska Blackhawk 10x42, or the wider-view Barska Adventure 7x35.
Compact vs full-size
Compact binoculars like the Barska Trend 8x21 and Lucid View 10x25 fit a jacket pocket and are great for travel, concerts and sightseeing. Their small lenses mean a dimmer image in poor light.
Porro vs roof prism
Porro-prism binoculars have the classic offset, zig-zag shape. Roof-prism binoculars have straight barrels and are usually more compact. Going by our listings, the Barska Blackhawk 10x42 and Lucid View 10x25 are roof-prism designs, while the Barska Adventure 7x35 uses porro prisms.
For boating: 7x50
On a moving boat, low magnification and a big exit pupil help. The Barska Marine 7x50 is a marine pair with BAK-4 prisms and an internal rangefinder and compass, and Barska says it floats.
Key takeaway: read the numbers. Magnification sets detail, lens size sets brightness, and the balance depends on what you're watching.
"More magnification isn't better if you can't hold the view steady."
Our picks
Bird watching: Barska Lucid View 10x42 or Blackhawk 10x42. Travel: Barska Trend 8x21. Boating: Barska Marine 7x50. Browse all binoculars.
Our binocular picks by use
From our Barska range. The two 10x42s are the bird-watching pairs; the 7x35 gives a wider view, and the 8x21 is the pocket pair for travel.
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Shop Now →Frequently Asked Questions
What does 10x50 mean on binoculars?
10x magnification and 50mm front lenses.
Are 8x42 or 10x42 binoculars better for bird watching?
8x42 gives a wider, steadier view that's easier for moving birds; 10x42 shows more detail but magnifies hand shake.
Are compact binoculars good for travel?
Yes. They're light and pocketable, but dimmer in low light than full-size pairs.
What is exit pupil?
The objective lens size divided by the magnification, for example 42 ÷ 8 = 5.25mm. Bigger is generally brighter in low light.
Heading outdoors? Browse the outdoor range.