Kowa BD III XD 10x42 vs Kowa BD III XD 8x42
Quick take: The Kowa BD III XD 10x42 reaches farther (10x vs 8x); the Kowa BD III XD 8x42 has a wider field of view (429 vs 378 ft @ 1000 yds).
Field of view, to scale
Top-down view · drawn to true scale — no exaggeration
Which one to buy
At the same $499 and nearly the same weight, 21.5 oz and 21.3, Kowa's two BD III XD models differ only in magnification, and the 8x42 lands on the better side of almost every trade. It shows 429 ft at 1000 yards against 378, has a 5.25mm exit pupil against 4.2mm, and 17.2mm of eye relief against 16.5mm. Both share fluorite-rich XD glass, a magnesium body and a 5.9 ft close focus, so neither gives anything up on butterflies.
The Kowa BD III XD 8x42 is the one for woodland, mixed habitat and dusk, and the one a first-time buyer should start with. The Kowa BD III XD 10x42 earns its place when the birds are far away: shorebirds across a mudflat, waterfowl on open water, raptors on a distant ridge. Its 378 ft field is the narrower of the two, so expect to work a little harder to get onto moving birds.
Kowa BD III XD 10x42
For open water, shorebirds and distant raptors, where the extra reach is the whole point.
Kowa BD III XD 8x42
The safer default at the same price: wider, brighter at dusk and slightly kinder to glasses wearers.
| Spec | Kowa BD III XD 10x42 | Kowa BD III XD 8x42 |
|---|---|---|
| Approx. price | ~$499 | ~$499 |
| Use case | Birding | Birding |
| Magnification | 10x | 8x |
| Objective | 42mm | 42mm |
| Exit pupil | 4.2mm | 5.25mm |
| Field of view | 378 ft @ 1000 yds | 429 ft @ 1000 yds |
| Eye relief | 16.5mm | 17.2mm |
| Close focus | 5.9 ft | 5.9 ft |
| Prism | Roof | Roof |
| Glass | ED | ED |
| Coating | Fully Multi-Coated | Fully Multi-Coated |
| Weight | 21.5 oz | 21.3 oz |
| Dimensions | 5.3 x 5.0 in | 5.3 x 5.0 in |
| Warranty | Limited Lifetime | Limited Lifetime |
Feature comparison
Kowa BD III XD 10x42
- ✓ED Glass
- ✗Phase-Corrected
- ✗Dielectric Coating
- ✓Waterproof
- ✓Fogproof
- ✗Image Stabilized
- ✗Tripod Adaptable
- ✓Magnesium Body
- ✗Locking Diopter
Kowa BD III XD 8x42
- ✓ED Glass
- ✗Phase-Corrected
- ✗Dielectric Coating
- ✓Waterproof
- ✓Fogproof
- ✗Image Stabilized
- ✗Tripod Adaptable
- ✓Magnesium Body
- ✗Locking Diopter
Kowa BD III XD 10x42 vs Kowa BD III XD 8x42: common questions
Is the Kowa BD III XD 10x42 or 8x42 better as a first birding binocular?▾
The 8x42. At the same $499 it gives a wider 429 ft field and a larger 5.25mm exit pupil, which make birds easier to find and the view brighter in shade or at dusk. The 10x42 suits buyers who already know they mostly watch distant birds.
Do the Kowa BD III XD 10x42 and 8x42 share the same glass and body?▾
Yes. Both use fluorite-rich XD glass in a magnesium-alloy body, both focus to 5.9 ft and both carry Kowa's limited lifetime warranty. Their weights are nearly identical, so the decision comes down to magnification alone.