Comparative analysis of the characteristics of Russian- and Chinese-made binocularsM. A. Ostrovskaya and V. I. Belikov

State Optical Institute, St. Petersburg, Russia

I. K. Yarov

Optomechanical Plant, Salavat, Russia~Submitted April 22, 1999!Opticheski� Zhurnal67, 80–82~March 2000!

The requirements placed on binoculars to ensure the possibility of binocular vision, as well asthe safety requirements for visual observation instruments that are tested during thecertification of products, are examined. The results of comparative tests of the characteristics ofbinoculars manufactured by Russian and Chinese companies are presented. ©2000 TheOptical Society of America.@S1070-9762~00!01803-0#

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Numerous and sundry models of prism binocularsfixed and variable magnification and of low, medium, ahigh aperture ratio having moderate and wide fields of visand various designs and external shapes have appearedworld market during the last twenty to thirty years. In the nvery distant past the leading producers of binoculars wJapan and Germany, as well as several countries in WesEurope. Binoculars were also mass-produced in the SoUnion. Today, the number of countries producing binoculhas grown with the addition of countries in Southeast A~China, Taiwan, and Korea!.

We have repeatedly assessed the quality of importedoculars from the well-known European and Japanmanufacturers.1,2 Nevertheless, an investigation of the quaity of binoculars from Asian countries, for example, Chinwould be of unquestionable interest.

The main requirements placed on the binoculars mafactured in Russia were described in Ref. 3, where the tyof binoculars, their designation, and use, as well as the mmum permissible deviations from the nominal optical chacteristics, such as magnification, magnification differen

275 J. Opt. Technol. 67 (3), March 2000 1070-9762/2000/030

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field of view, exit pupil diameter and location, resolutiolimit, parallelism of the optical axes of the monoculars, etwere established. It should be noted that the most significcharacteristics of binoculars, which determine the possibiof using them for viewing by both eyes~the possibility ofbinocular vision! are the deviation of the bundles of rayemerging from the eyepieces from parallelism and the diffence between the magnifications of the two monoculars. Tis because human binocular vision is possible only ifvisual axes of both eyes converge at a single point in subspace, i.e., the fixation point. When the visual axes of beyes are coordinated, this condition is always automaticsatisfied for a binocularly fixed subject owing to the accomodative convergence of the human visual system.4 If thecoordination of the visual axes of the eyes is disturbed~forexample, in the case of latent strabismus or in working wa binocular instrument, in which the optical axes of the mnoculars are nonparallel!, this condition is not satisfied automatically, and its fulfillment requires additional eye movments called fusion movements.5 Double images areeliminated, and fusion convergence is achieved by th

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TABLE I. Results of measurements of the optical characteristics of 10325 binoculars.

Characteristicsof binoculars

Requirements ofRef. 3 and Tech. Spec.

Model name

BPTs 10325 ~SOMP! Panolux 10325 ~China!

Interpupillary distance, mm 56 65 74 56 65 74Parallelism tolerances, minin horizontal plane:

divergence 60 20 25 15convergence 20 84 85 120

in vertical plane 20 5 0 3 0 20 5

Monocular left right left right

Magnification,3 1060.5 10 10 10 10Exit pupil diameter, mm 2.560.13 2.5 2.6 2.4 2.4Exit pupil location, mm 9.760.97 10 10 10 10Field of view, deg 6.060.3 6 6 5.6 5.6Resolution limit, sec 7.2 6.5 6.5 6.9 7.7Image quality good good good gooTransmission coef., % 71 72 75 58 58

275275-03$18.00 © 2000 The Optical Society of America

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TABLE II. Results of measurements of the optical characteristics of 10350 binoculars.

Characteristicsof binoculars

Requirements ofRef. 3 and Tech. Spec.

Model name

BPTs 10350 ~SOMP! WT 10350 ~China!

Interpupillary distance, mm 56 65 74 56 65 74Parallelism tolerances, minin horizontal plane:

divergence 60 20 25 15convergence 20 84 85 120

in vertical plane 20 5 0 3 0 20 5

Monocular left right left right

Magnification,3 1060.5 10.1 10.1 10.3 9.9Exit pupil diameter, mm 560.25 5.0 5.0 4.535 4.535Exit pupil location, mm 15.331.5 15.3 15.4 11 11Field of view, deg 660.3 6.0 6.0 5.9 5.9Resolution limit, sec 4.5 2.8 2.8 2.8 3.8Image quality good good good goodTransmission coef., % 71 78 76 74 74

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movements. However, any fusion movement requires sostraining of the eye musculature. The greater is this strainthe less stable is the position to which the eyes are brouby fusion movements. Work with binocular instrumenwhich is associated with the performance of certain tasksrequires a long viewing time, naturally, cannot be carriedwith nonparallelism of the axes of the binocular instrumethat corresponds or is close to the limit of the fusion abilof the eyes, since the great muscular strain in the eyes incase would give rise to visual discomfort, i.e., suchthenopic phenomena as dizziness, pain in the temples, qfatigue, headache, and a sense of ‘‘heaviness’’ in the eThe use of such binoculars would adversely affect healthcan lead to complications and deterioration of a persovision. For this reason, when binoculars are manufacturigid requirements are placed on the permissible deviatiof the bundles of rays of binoculars emerging from the epieces from parallelism, which are specified by the followivalues:

divergence of the bundles of rays in the horizontal planot exceeding 608,

convergence of the bundles of rays in the horizonplane not exceeding 208,

divergence of the bundles of rays in the vertical planot exceeding 208.

It should be noted that a difference between the magfications of the monoculars of binoculars exceeding 1.5–has a similar negative influence on the visual system operson using binoculars.

Failure to satisfy the requirements enumerated abovbinoculars can be harmful to a person’s health. At the satime, a user of binoculars has no possibility to independemonitor the correspondence of the characteristics of binolars to the required tolerances. For this reason, a SStandard6 containing a series of safety requirements~includ-ing tolerances for the parallelism of the bundles of raemerging from the eyepieces and tolerances for the mag

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cation difference in binoculars!, to which the special attention of both manufacturers and consumers should berected, was developed. Decision No. 1013 of the governmof the Russian Federation of August 13, 1997, confirmedlist of goods subjected to obligatory certification with cosideration of safety requirements.7 This list also includes bin-oculars. According to this decision, binoculars producedRussia, as well as binoculars offered for sale, must undetesting and be certified. In this context there is unquestiable interest in assessing the quality of binoculars from cotries in Southeast Asia that have appeared on the maComparative testing of three models of binoculars manuftured in China, as well as the Russian 10350 and 10325models from the Salavat Optomechanical Plant~SOMP!, wascarried out. The optical characteristics of the binoculars wmeasured in a room at normal ambient temperature, andmatic thermal testing for compliance to the requirementsState Standard 7048-81, according to which binoculars mmaintain their operability at ambient temperatures inrange from230 to 145 °C, was also carried out.

The values of the measured characteristics of the binolars are presented in Tables I–IV.

An analysis of the results of the testing of the binoculaallows us to conclude that the values of the optical char

TABLE III. Results of measurements of the optical characteristics of MCoated 9227350 binoculars~China!.

Characteristicsof binoculars

Requirements of Ref. 3and Technical Specifications

Model name

Value

Magnification,3 9 27Parallelism tolerances, minin horizontal plane:divergence 60 1 47convergence 20in vertical plane 20 52 90

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TABLE IV. Characteristics of binoculars during thermal testing.

ModelAmbient

temperature, °CDeviation of emerging rays

from parallelism, min

Interpupillary distance, mm

56 65 74

ST 10350 normal in horiz. plane 84 con. 85 con. 120 coin vert. plane 0 20 5

210* in horiz. plane 78 con. 78 con. 120 conin vert. plane 8 3 10

145 in horiz. plane 97 con. 96 con. 150 coin vert. plane 2 1 10

Multi Coated 9227350 210** in horiz. plane 3 div. 24 con. 62 con.in vert. plane 2 14 17

145 in horiz. plane 61 con. 140 con.in vert. plane 33 30

*Eyepiece motion jams.** Central focusing mechanism and eyepiece motion jam.

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teristics of the Chinese binoculars tested are generally cparable to the characteristics of the analogous Russian mels and do not exceed the tolerance ranges in most casethe same time, it is noteworthy that the safety characterisof the binoculars, i.e., the deviation of the bundles of raemerging from the eyepieces from parallelism, exceedpermissible ranges by a factor of 4–6 in all the modelsChinese binoculars.

The climatic thermal tests attest to a lack of stabilitythe functioning of the movable mechanisms in the binolars. When the ambient temperature was lowered to210 °C, the mechanism for central focusing and focusingthe right-hand eyepiece jams. The binoculars to not confoto the requirements that ensure the possibility of using thunder the conditions in Russia.

Thus, the testing data showed that binoculars appea

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on the market must be carefully monitored to ensuresafety of their use by people. The testing results confirmappropriateness of the requirements for the obligatory cefication of binoculars according to their safety charactetics.

1M. A. Ostrovskaya, ‘‘Contemporary foreign binoculars,’’ Opt.-MekhProm-st’46~8!, 47 ~1979! @Sov. J. Opt. Technol.46, 489 ~1979!#.

2T. E. Balashova, M. A. Ostrovskayaet al., Opt. Prib. Tovary Narodn.Potrebleniya, No. 1, 15~1987!.

3State Standard 7048-81. Binoculars. Types and Basic Parameters.eral Technical Requirements@in Russian#, Gosstandart, Moscow~1981!.

4H. Schober, Das Sehen11, 321 ~1958!.5H. Schober, Das Sehen11, 339 ~1958!.6State Standard R5 0909-96. Visual Observation Instruments. Safetyquirements and Testing Methods@in Russian#, Gosstandart, Moscow~1996!.

7Rossi�skaya Gazeta~August 21, 1997!.

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