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Using Binoculars to see at distances

Kowa Prominar BD42 Binoculars

kowa prominar bd42 Birders have long been familiar with the name of Kowa, since their excellent spotting scopes are commonly seen in the field. By comparison, although they have been on the market for some years now, Kowa binoculars are still only infrequently encountered. After having a chance to play with the 8x42 DCF and 10x42 DCF BD42 binoculars, we are somewhat at a loss to explain why. These are excellent binoculars, well designed, stylish, lightweight, comfortable to use, and moderately priced. There should be more of these out there!

The first thing that grabs the attention is the look. At just 5.75 inches tall by 5 inches wide, the Kowa Prominar roof prisms have a sleek and slender look. This appearance is confirmed by picking them up: at just 25.8 oz. for the 8x42, and 26.3 oz. for the 10x42, both models are comfortably light in the hands. Encased in no-slip, textured, rubber armor with shallow, wide thumb grooves on the barrels, the Kowas fit naturally and comfortably in the hands. The color scheme is distinctive too: available in pale gray with slate gray trim or a kind of purplish blue with a silver plastic accent across the body, these binoculars won’t be readily mistaken for any others.

Optically, the Prominar binoculars deliver what you’d expect. They are fully phase-coated to minimize distortion, and multi-coated to maximize light transmission. They are very bright, and the color fidelity is excellent, even in the fading light of evening. The image is tack sharp right to the edge of the field, with virtually no edge effect. We did note some color aberration on high contrast objects under really bright light conditions and this effect is not restricted to the edges of the field. The 8x42 model boasts a field of 361 feet at 1000 yards, while the 10x42 are only slightly more restricted at 341. These are both good or even above average for binoculars of the respective types. Both models close focus to 6.5 feet, which is excellent. Focus adjustment is with a central knob that is large, and made of grooved rubber for good purchase. The knob turned quite easily on the 8x42 model we reviewed, but was somewhat stiffer on the 10x42, perhaps reflecting its newness. Going from minimum close focus to infinity required 1 and a 1/3 turns of the knob, which is pretty good. Even on the stiffer of the two models, sharp focus was easy to achieve.

Eye relief on the 8x42 model is 18.3 mm, while the 10x42 comes in at 14.2 mm; both somewhat low for this characteristic. This won’t bother a user who wears glasses, but it might be too close for comfort for users with uncorrected vision. The eyecups twist counter clockwise to reach their full extension, and there is a click-stop to stabilize them there. No intermediate positions available. The diopter adjustment is the most common type: a rubber-armored ring on the right ocular twists in either direction to adjust the focal length. The position for equal eyes is marked by a gap between the “+” and “-” arrows on the dial that lines up with a vertical hash mark on the barrel. This works fine for those whose eyes are equal. The shortcoming of this system is that nothing marks the adjustment for those whose eyes require unequal settings, so if something moves the ring, the readjustment has to be made from scratch. Fortunately, there is a fair amount of resistance against moving the ring so it won’t twist out of place easily.

Prominar binoculars are fully sealed, nitrogen-purged and waterproof under normal conditions, so they will stay fog-free in the field. In case the weather gets nasty, Kowa has provided their version of the optimal rain guard: two soft rubber cups joined by a flexible linker region. The cups fit easily over the oculars, and yet the fit is snug - the rain guard doesn’t dislodge even when the optic is inverted and shaken. The strap threads through a bracket on the left side. The right side bracket is gapped to allow it to be easily attached or detached from the strap on that side. The lens caps are hard plastic, and fit firmly in the barrels, relying on friction with the rubber armoring to hold them in place. Kowa has seen fit to equip the caps with a gapped bracket, so they too may be attached to the strap when not in use. This isn’t a system we’re fond of. The brackets on the lens caps serve as a handle to knock them off with, so, for example, unless the brackets are turned in towards each other, just pulling the binocular out of the case dislodges them.

The strap on the 10x40 Victory is a hybrid of cordura and a soft, cloth-covered neoprene center section that cushions the neck. The padded section is angled in a way that causes the binocular to settle more comfortably against the chest, an innovative design. The strap attaches to plastic clips that swing freely around a metal pole on the barrels. The clips can actually be unsnapped and removed from the poles altogether, which makes it easy to change between straps. The swinging clips minimize entanglement of the straps in the hands when the binoculars are lifted to the face, and this is a significant innovation for comfort and ease of use.

Overall, we were quite impressed with the Kowa Prominar BD42 series of binoculars. Priced at $590.00 for the 8x42 model and $615.00 for the 10x42 version, these binoculars are an excellent value. Maybe Kowa just hasn’t overcome the fact that, to many birders, they are still primarily a scope company. The fact is, these binoculars deliver high-end performance for a mid-to-low range price, and if more people pick them up and play with them at festivals and shows, more and more birders will be buying them.


Kowa Prominar BD-42 Binoculars - current price and availability