Binoculars review

Olympus 10x42 EXPS I

Olympus 10x42 EXPS I
11 March 2010
The EXPS I series consists of three porro-prismatic models with the following parameters: 8x42, 10x42 and 12x50. The binoculars are put into a solid, rubber-coated housing, with BaK-4 glass prisms and fully multi-coated lenses. Additionally UV coatings were used, limiting the transmission of harmful rays from that part of the spectrum.

In the case of the 10x42 model, according to the producer, an optical system made of 8 elements in 6 groups, was applied.

  • Lornetka Olympus 10x42 EXPS I
  • Lornetka Olympus 10x42 EXPS I
  • Lornetka Olympus 10x42 EXPS I
  • Lornetka Olympus 10x42 EXPS I
Manufacturer data


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Magnification Lens diameter Angular field of view Prisms Eye relief Weight Price
10 42 96.1/1000(5.5o) BaK-4/Porro 18.4 mm 785 g 579 PLN
Results of the review
Real front lens diameter Left:   42+/- 0.05 mm
Right:  41.98+/- 0.05 mm
8 / 8.0 pkt
Real magnification 10.07+/- 0.15x 3/3.0
Transmission 86+/- 3% 13.5/25.0
Chromatic aberration Low in the centre and at the edge. 7.4/10.0
Astigmatism Visible. 4.8/10.0
Distortion The distance of the first curved line from the field centre compared to the field of view radius: 53% +\- 6% 6/10.0
Coma Medium. 6.3/10.0
Blurring at the edge of the FOV The blur occurs in the distance of 87% +\- 6% from the field of view centre. 7/10.0
Darkening at the edge the FOV Slight. 4.2/5.0
Whiteness of the image Light yellow. 4.3/5.0
Collimation Exemplary. 5/5.0
Internal reflections
Left: Right:
Olympus 10x42 EXPS I - Internal reflections - Left Olympus 10x42 EXPS I - Internal reflections - Right
Very distinct.
Housing Solid, good quality padding, comfortable to hold and to look through. Regulated eyecups but they move heavily. 7.5/8.0
Focusing Big comfortable central screw (280 degrees) but it moves with light squelch. Stable bridge, the pressure doesn’t cause defocusing. Metal screw on the right eyepiece moderately convenient; it moves the lens. 4.2/5.0
Tripod There is a comfortable exit. 3/3.0
Interpupilary distance from 58.3 to 72.5mm 3/6.0
Closest focusing distance 2.8 m. 1/2.0
Eyepieces FOV Apparent field of view of 56.4 deg (according to simple formula) and 52.4 deg (according to tangent formula). 8/20.0
Field of view Measured by us amounted to 5.60 +\- 0.03 degrees and it was by 0.10 degree wider than stated in the specifications. 5/8.0
Quality of the interior of the barrels Black but slightly shiny inner tubes. Gray and a bit scratched bottom. Black glue. Clean. 3.4/5.0
Left: Right:
Olympus 10x42 EXPS I - Vignetting - Left Olympus 10x42 EXPS I - Vignetting - Right
OL: 0.9% OR: 0.3%.
Prisms quality Good quality BaK-4. 8/8.0
Antireflection coatings Purple-green on the objectives and eyepieces. Green on the prisms. Medium intensity. 4.5/5.0
Warranty [years] 25 5/6.0
Final result
25th place in the overall ranking of the 10x42 binoculars test.
130.7 / 190 pkt
Econo result 2 place in the econo ranking of the 10x42 binoculars test. 17.6pkt.


  • solid housing,
  • quite good image sharpness at the edge of the field,
  • good transmission,
  • good whiteness rendition,
  • good quality of prisms and coatings,
  • low brightness loss at the edge of the field,
  • slight chromatic aberration,
  • long guarantee.

  • very distinct flares,
  • the maximum eyepieces’ gauge a bit too narrow,
  • the field of view could have been wider,
  • noticeable astigmatism.

Once again we have here an interesting duel between four very good and very similar sets of binoculars. In alphabetical order these are as follows: the Bynolyt Seal 10x42 BCF, the Olympus EXPS-I 10x42, the Opticron Imagic TGA WP 10x42 and the Swift Optics 962 Ultra Lite 10x42. All of them are classic Porro devices, with their dimensions very much alike. Their weight is in the 670-785 grams range, their fields of view amount to exactly 5.5 degrees and eye relief distances – from 18 to 21.5 mm. The most curious thing is that even their market prices in Poland don’t differ greatly – they range from 650 to a bit over 1000 PLN (arount 250-300 USD).

Looking at these binoculars and their parameters we see at once that their potential is great. First of all we deal here with an efficient and simple Porro construction which, for an amount of about 250-300 USD, can offer a lot. Apart from that, the limited field of view of 5.5 degrees allows us to expect no serious slip-ups at its edge.

None of these binoculars disappointed us and the Swift’s performance was just excellent with the sensational price/quality ratio. The Bynolyt and the Opticron can speak about bad luck here- if it wasn’t for the Swift we would write about them very warmly here. The Olympus’s main advantage is the lowest price, which might influence seriously the interest in this instrument. Undoubtedly all the binoculars have a lot of advantages but the Swift has them significantly more of them. As it costs almost the same or just a tad more than the rivals, the choice is really rather simple unless somebody doesn’t like its original housing and a bit heavier weight (although personally I doubt anybody would mind a difference of 20-40 grams) or will be persuaded by the attractive price of the Olympus.

If I started to get interested in a 10x42 class product only one thing about it would make me feel anxious – that field of view, amounting to only 5.5 degrees. There’s no doubt that good results of those four sets of binoculars are partially the effect of such a narrow field. Most of the 10x42 instruments have a field of view at the level of 6 degrees and we can even find models with the value of 6.5 degrees. Personally I wouldn’t accept a field of view of 5 degrees in a pair of binoculars with the magnification 10x and the 42 mm objective lens – I am not very keen on such instruments because their eyepieces’ field of view is so small that I have the impression of looking through a narrow pipe. Fortunately when we increase the field from 5 to 5.5 degrees that impression disappears and it seems that the angle of 5.5 degrees is the minimum I would be able to accept because I get a lot in return for this restriction.

The Allbinos.com/Optyczne.pl editorial team decided to award this set of binoculars the “A good buy according to the Allbinos.com/Optyczne.pl Editorial Team” distinction for winning the 2nd place in the 10x42 binoculars Econo ranking