Binoculars review

Ecotone SR-4 10x42

Ecotone SR-4 10x42
22 August 2010
The Ecotone company from the Polish Tri-Cities area produces its binoculars in China and Japan and its offer is getting wider and wider. One of more interesting offers, launched on the market in 2005, was the Ecotone SR-4 10x42 binoculars.

As Ecotone aims its products mainly at ornithologists, small wonder the SR-4 model was produced with classic “birding” parameters of 10x42. We are also not surprised by the fact that the prisms are put in the roof system. Here the typicality of the Ecotone stops, though. First of all, in the case of this instrument we deal with a wide field of view. Te Schmidt- Pechan system prisms are phase correction coated and the reflecting surface was covered not by ordinary aluminum but by silver. The producer decided to use low-dispersion glass in the construction which is supposed to ensure excellent chromatic and spherical aberration correction. Additionally all the air-to-glass surfaces in the binoculars were covered by high quality antireflection coatings. The device is also waterproof and nitrogen-filled.

  • Lornetka Ecotone SR-4 10x42
  • Lornetka Ecotone SR-4 10x42
  • Lornetka Ecotone SR-4 10x42
  • Lornetka Ecotone SR-4 10x42
Manufacturer data


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Magnification Lens diameter Angular field of view Prisms Eye relief Weight Price
10 42 114/1000(6.5o) BaK-4/roof 16 mm 840 g 1497 PLN
Results of the review
Real front lens diameter Left:   42.1+/- 0.05 mm
Right:  42.13+/- 0.05 mm
8 / 8.0 pkt
Real magnification 10+/- 0.15x 3/3.0
Transmission 85+/- 3% 12.5/25.0
Chromatic aberration Low in the centre, average at the edge. 7.5/10.0
Astigmatism Medium. 5.7/10.0
Distortion The distance of the first curved line from the field centre compared to the field of view radius: 45% +\- 3% 5/10.0
Coma Low. 6.3/10.0
Blurring at the edge of the FOV The blur occurs in the distance of 82% +\- 5% from the field of view centre. 6/10.0
Darkening at the edge the FOV Low. 4/5.0
Whiteness of the image Light yellow cream. 3.8/5.0
Collimation Exemplary. 5/5.0
Internal reflections
Left: Right:
Ecotone SR-4 10x42 - Internal reflections - Left Ecotone SR-4 10x42 - Internal reflections - Right
Visible. False pupils.
Housing Very solid and compact. Great comfort of observation. Good quality padding. Regulated eyecups with too much grease. 7.6/8.0
Focusing In fact the binoculars can be focused using just one finger and two comfortable central screws. Nothing moves outside. Individual focusing lever is a bit too short and in extreme positions it is too near the inner tubes – sometimes it is difficult to pull it back. Central screw has a 450-degree turn. Both screws move smoothly and conveniently. 4.5/5.0
Tripod No. 0/3.0
Interpupilary distance from 57.1 to 72.6mm 3/6.0
Closest focusing distance 2.2 m. 1.5/2.0
Eyepieces FOV Apparent field of view of 65.5 deg (according to simple formula) and 59.6 deg (according to tangent formula). 14/20.0
Field of view Measured by us amounted to 6.55 +\- 0.03 degrees and was a bit wider than in the specifications. A wide field of view for this equipment class. 7/8.0
Quality of the interior of the barrels Inner tubes black-gray and matt. Slightly shiny bottom. Microscopic specks of dust. 3.9/5.0
Left: Right:
Ecotone SR-4 10x42 - Vignetting - Left Ecotone SR-4 10x42 - Vignetting - Right
OL: 1.8%, OR: 0.4%.
Prisms quality High quality BaK-4. 8/8.0
Antireflection coatings Green-pink-yellow everywhere. Low intensity. 5/5.0
Warranty [years] 5 3.5/6.0
Final result
26th place in the overall ranking of the 10x42 binoculars test.
133.7 / 190 pkt
Econo result 19th place in the econo ranking of the 10x42 binoculars test. 4.4pkt.


  • wide field of view and relatively sharp at the edge,
  • very solid housing,
  • low coma,
  • chromatic aberration well-corrected,
  • low light fall-off at the edge of the field,
  • quite good transmission,
  • high quality of coatings and prisms.

  • slightly truncated pupils,
  • lack of tripod exit,
  • distinct false pupils.

The Ecotone SR-4 reminds us of the Docter 10x42, the Bresser Montana and the Bushnell Discoverer very much. All of them have similar, quite significant weight, compact and solid housing, identical focusing system, wide field of view and minimal focus distance; the slip-ups are also the same - false pupils and the lack of a tripod exit.

It is difficult to tell unambiguously whether or not Ecotone followed the example of Docter. Even if it was the case, though, the student got better than the master in some categories and the copy was proven to be better than the original thing. The Ecotone corrects the chromatic aberration better and has a sharper field of view edge, most probably because of the usage of the low-dispersion glass. The final score is very similar to that of the Docter but the price - significantly lower. Also a clash with the Bushnell Discoverer must be won by the Ecotone because the score is practically the same but the price of the Ecotone – lower by more than 100 USD.