Binoculars reviews

Endurance test of 8x42 binoculars

30 April 2013
Arkadiusz Olech

10. Kowa BD42-8 8x42

Endurance test of 8x42 binoculars - Kowa BD42-8 8x42

The Kowa BD series of binoculars consists of some reliable instruments, present on the market for several years. They get good results in our tests and it seems they are an example of solid Japanese workmanship. The 8x42 model managed to gather 121.5 points in our optical test – let’s check how it fared in the endurance one.

Low temperature

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After a longer time in low temperature the binoculars’ central wheel is rather hard to move but it concerns only the first turn. The next ones are much easier to perform and the resistance isn’t noticeably higher than in room temperature. The change of the gauge of the tubes is also difficult. We didn’t have any reservations concerning the performance of the individual focus ring, the tripod mounting and the eyecups.

High temperature

In the case of the high temperature test the individual focus ring, the eyecups and the tripod mounting performed once again as they should. The central wheel moved far too loosely, though, and the rubber next to objectives became a bit too soft. We didn’t notice any grease leakages outside or inside the tubes.

Waterproof qualities

No reservations in this category. The binoculars survived one hour submersion without any problems.


Two falls from different heights didn’t cause any serious problems. There are no traces of them on the cases and the binoculars remained perfectly collimated. The only fault appeared when the binoculars hit the floor with the eyecups – as a result they got skewed and derailed. Still we managed to set them right again without any problems and after a while they were functioning as they should.

Optics cleaning

Water residue, which got stuck after the exposure to high temperature, is very difficult to remove; the fingerprints are an easier task – one or two swipes of a dry cloth are enough. The water leaves a lot of droplets when dribbling down. A big grease stain can be smeared on the element and it is very difficult to remove using only the cloth.


No other flaws.


The chart below shows the results the tested pair of binoculars got in particular categories:

Low temperature:
High temperature:
Waterproof quality:
Optics cleaning:

The Kowa didn’t disappoint us – there were no serious slip-ups in the test although in several categories the device lost some points due to minor problems. The result of 41 points should be considered very good – the binoculars emerged from all our tests unscathed. Its appearance also confirms it – after a year and a half of intensive wear and tear the instrument still looks as good as new.