Binoculars review

Vortex Sidewinder 10x42

Vortex Sidewinder 10x42
13 December 2010
It was a kind of a ghost series –before it managed settle in for good on our market the producer decided to swap it for a series called Diamondback. Diamondbacks are not available yet but their parameters are the same as those of the Sidewinders. Judging by photos, their appearance hasn’t changed either.

The Sidewinder series consisted of two roof prism 8x42 and 10x42 models. The prisms were made of BaK-4 glass and were phase correction coated. The binoculars were produced in China.

  • Lornetka Vortex Sidewinder 10x42
  • Lornetka Vortex Sidewinder 10x42
  • Lornetka Vortex Sidewinder 10x42
  • Lornetka Vortex Sidewinder 10x42
Manufacturer data


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Magnification Lens diameter Angular field of view Prisms Eye relief Weight Price
10 42 116/1000(6.6o) BaK-4/roof 16 mm 692 g 669 PLN
Results of the review
Real front lens diameter Left:   41.97+/- 0.05 mm
Right:  41.95+/- 0.05 mm
8 / 8.0 pkt
Real magnification 9.87+/- 0.15x 3/3.0
Transmission 76+/- 3% 8/25.0
Chromatic aberration Low in the centre, higher on the edge. 5.7/10.0
Astigmatism Slight. 6.5/10.0
Distortion The distance of the first curved line from the field centre compared to the field of view radius: 25% +\- 3% 2/10.0
Coma Slight. 6/10.0
Blurring at the edge of the FOV The blur occurs in the distance of 82% +\- 4% from the field of vision centre. 6/10.0
Darkening at the edge the FOV Noticeable. 3.2/5.0
Whiteness of the image Distinct yellow cream. 2.7/5.0
Collimation Exemplary. 5/5.0
Internal reflections
Left: Right:
Vortex Sidewinder 10x42 - Internal reflections - Left Vortex Sidewinder 10x42 - Internal reflections - Right
Slight but noticeable. False pupils.
Housing Handy, quite compact and solid. Comfortable to hold and to look through. Eyecups without detented stops but they don’t collapse in indirect positions. 7.1/8.0
Focusing Very comfortable central wheel (540 degrees). Comfortable individual focusing which moves the lens and works very tightly. 4.5/5.0
Tripod There is a convenient exit. 3/3.0
Interpupilary distance from 55.7 to 73.3mm 4/6.0
Closest focusing distance 1.5 m. 2/2.0
Eyepieces FOV Apparent field of view of 60.9 deg (according to simple formula) and 56.0 deg (according to tangent formula). 11.5/20.0
Field of view Measured by us amounted to 6.17 +\- 0.03 degrees and it was by 0.43 of a degree narrower than the value given in specifications. 2/8.0
Quality of the interior of the barrels Black but slightly shiny. Grey bottom. Specks of dust on the left prism. 3.7/5.0
Left: Right:
Vortex Sidewinder 10x42 - Vignetting - Left Vortex Sidewinder 10x42 - Vignetting - Right
OL: 2.2%, OR: 3.9%.
Egg-shaped pupils.
Prisms quality Good BaK-4. 8/8.0
Antireflection coatings Green on the objective lenses. Green-purple on the eyepieces. Green on the prisms but one air-to-glass surface seems to be not covered. Medium intensity. 3.7/5.0
Warranty [years] Lifetime warranty 6/6.0
Final result
47th place in the overall ranking of our 10x42 binoculars’ test.
119.6 / 190 pkt
Econo result 21st place in the econo ranking of our 10x42 binoculars’ test. 4.1pkt.


  • solid casing,
  • high class of prisms,
  • minimum focus already from 1.5 metres,
  • lifetime warranty,
  • coma and astigmatism corrected quite well.

  • field of view significantly smaller than provided in the specifications,
  • hefty distortion,
  • egg-shaped exit pupils,
  • average whiteness rendition.

This pair of binoculars features a quite good price/quality ratio but I am not sure whether it is really worth our interest when for 60 USD less we can buy a Vortex Crossfire which scored just 1.4 points less in our test. Perhaps exactly that small difference between the Sidewinder and the Crossfire was a reason why the former was superseded by the Diamondback.