Astronomy binoculars
Two 10x50s — what is under the same three numbers?
Magnification, aperture and exit pupil are identical because all three follow from the name. Underneath, one of these publishes its prism glass, its coating grade, its weight and what is in the box; the other publishes the word "coated".
| Compared on | Wave 10x50 (1331050) | Falcon 10x50 (13-3450C) |
|---|---|---|
| Aperture | 50 mm | 50 mm |
| Magnification | 10x, fixed by the design | 10x, fixed by the design |
| Exit pupil | 5 mm — 50 divided by 10 | 5 mm — 50 divided by 10 |
| True field of view | Not published by the maker. | The listing does not carry it |
| Prism type and coatings | BaK-4 glass, full multi-coating plus the maker’s UR coating | Porro, from the product name; coated lenses, as the maker words it — the weakest of the four labels |
| Eye relief | Twist-up eyecups, dioptre compensation, metal centre focuser | Not published by the maker. |
| Weight | 758 g, as the maker publishes it | Not published by the maker. |
| Supplied accessories | Strap, case, protective caps | Not published by the maker. |
A tick means one listing published something the other did not, or published a better figure. It does not mean the product is better, and the column is not a score out of anything: a maker who says less loses lines here without losing a comparison. The two verdicts below are where the page is settled.
The one that describes itself. BaK-4 glass and full multi-coating are the two labels that separate binoculars whose headline figures are identical, and both are stated. Seven hundred and fifty-eight grams is published, which decides how long it can be held up.
A long-running model sold on its name. "Coated" is the weakest of the four conventional coating labels — it means at least one surface has at least one layer — and nothing else about the glass, the weight or the contents appears. Neither listing publishes a true field of view, which is the figure a binocular is most usefully compared on.
Coated, fully coated, multi-coated and fully multi-coated, in ascending order. They describe how many surfaces are treated and with how many layers, and they are a convention rather than a measurement.
In a porro prism, BaK-4 gives a round exit pupil where BK-7 can show a squared-off edge, which means less light lost at the edge of the field. It is a real difference and a small one.
Because it decides how long it can be held steady. Above roughly a kilogram most observers need a support, and hand tremor is what limits detail long before the optics do.
10x · 50 mm · 758 g · waterproof and gas-filled
A waterproof, gas-filled 10x50 with BaK-4 glass, UR coating, twist-up eyecups and a metal centre focuser, published with its weight and dimensions.
Best for: Dusk and astronomy use in weather that would worry an unsealed pair
≈ $166 / £145 / €136
10x magnification · 50 mm objectives · porro prisms
A long-running 10x50 porro binocular from Bushnell’s Falcon line, with coated lenses and no gas filling or weather sealing claimed.
Best for: A first pair kept in the car for whatever the sky or the day offers
≈ $47 / £53 / €52
Any figure written into the body of this page was true on the day it was written. The amount shown next to each instrument is requested from the retailer as the page loads, and it is that amount, not the text, that stands.
