© ISO 2016 Optics and photonics — Test methods for telescopic systems — Part 3 Test methods for telescopic sights Optique et photonique — Méthodes d’essai pour systèmes télescopiques — Partie 3 Méthod[.]
INTERNATIONAL STANDARD ISO 4490-3 Second edition 01 6-02 -1 Optics and photonics — Test methods for telescopic systems — Part : Test methods for telescopic sights Optique et photonique — Méthodes d’essai pour systèmes télescopiques — Partie 3: Méthodes d’essai pour viseurs de tir Reference number ISO 4490-3 : 01 6(E) © ISO 01 ISO 14490-3 :2 016(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2016, Published in Switzerland All rights reserved Unless otherwise speci fied, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country of the requester ISO copyright office Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2016 – All rights reserved ISO 14490-3 :2 016(E) Contents Foreword Page Scope Normative references Terms and definitions Method of measurement of axial parallax 1 Te s t arran ge m e n t G e n e ral C o l l i m ato r Te l e s co p i c s i gh t D i o p tri c te s te r M e as u re m e n t p ro ce d u re 4 Te s t re p o rt Method of measurement of parallax P ri n ci p l e Te s t arran ge m e n t G e n e ral 2 C o l l i m ato r Te l e s co p i c s i gh t Li gh t s to p Auxiliary telescope M e as u re m e n t p ro ce d u re 5 Te s t re p o rt Method of measurement of eye relief range 6.1 P ri n ci p l e 6.2 Te s t arran ge m e n t 6.2 G e n e ral 6.2 C o l l i m ato r 6.2 Te l e s co p i c s i gh t Measuring magni fier 6.3 M e as u re m e n t p ro ce d u re 6.4 Te s t re p o rt Method of measurement of reticle tracking 7.1 P ri n ci p l e 7.2 Te s t arran ge m e n t 7.2 G e n e ral 7.2 C o l l i m ato r 7.3 Te s t p ro ce d u re 7.4 Te s t re p o rt Method of measurement of line of sight shift due to zooming 8.1 P ri n ci p l e 8.2 Te s t arran ge m e n t 8.2 G e n e ral 8.2 Te s t s p e ci m e n m o u n ti n g 1 8.2.3 8.3 P ri n ci p l e 6.2.4 5.2.5 v Auxiliary telescope 11 Te s t p ro ce d u re 1 8.3.1 Preparation of the test assembly 8.3 D e te rm i n ati o n o f th e m e as u re m e n t val u e s 1 11 8.4 P re ci s i o n o f th e m e as u re m e n t 8.5 Te s t re p o rt Method of measurement of line of sight shift due to focusing © I S O – Al l ri gh ts re s e rve d 12 iii ISO 14490-3 :2 016(E) 9.1 P ri n ci p l e 9.2 Te s t arran ge m e n t 9.2 G e n e ral 9.2 C o l l i m ato r 9.2 Te l e s co p i c s i gh t 9.2.4 9.3 10 iv Auxiliary telescope 14 Te s t p ro ce d u re 9.3.1 Preparation of the test assembly 9.3 D e te rm i n ati o n o f th e m e as u re m e n t val u e s 14 9.4 P re ci s i o n o f th e m e as u re m e n t 9.5 Te s t re p o rt General test report 15 © I S O – Al l ri gh ts re s e rve d ISO 14490-3 :2 016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work of preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the different types of ISO documents should be noted This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso.org/directives) Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights ISO shall not be held responsible for identifying any or all such patent rights Details of any patent rights identi fied during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement For an explanation on the meaning of ISO speci fic terms and expressions related to conformity assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 172 , Optics an d ph otonics, Subcommittee SC 4, Telescopic system s This second edition cancels and replaces the first edition (ISO 14490-3:2004), which has been technically revised with the following changes: a) Clause “Method of measurement of line of sight shift due to focusing” was added; b) the term “magni fication” was replaced by “magnifying power” in various instances ISO 14490 consists of the following parts, under the general title Optics an d ph otonics — Test m eth ods for telescopic system s : — Part : Test m eth ods for basic ch aracteristics — Part 2: Test m eth ods for bin ocular system s — Part 3: Test m eth ods for telescopic sights — Part 4: Test m eth ods for astron omical telescopes — Part 5: Test m eth ods for tran smittan ce — Part 6: Test m eth ods for veilin g glare in dex — Part 7: Test m eth ods for lim it of resolution — Part 8: Test m eth ods for nigh t-vision devices © ISO 01 – All rights reserved v INTERNATIONAL STANDARD ISO 14490-3 :2 016(E) Optics and photonics — Test methods for telescopic systems — Part : Test methods for telescopic sights Scope This part of ISO 14490 speci fies test equipment and test procedures for determination of the following o p ti c a l ch a rac te r i s ti c s o f te le s co p ic s i gh ts : — a x i a l p a l l a x; — p a r a l l a x; — eye relief range; — re tic le tracki n g ; — l i ne o f s i ght s h i ft due to z o o m i n g ; — l i ne o f s i ght s h i ft due to fo c u s i n g Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies Optics and photonics — Vocabulary for telescopic systems — Part 1: General terms and alphabetical indexes of terms in ISO 141 32 ISO 141 –1 , I S O 141 –3 , ISO Optics and photonics — Vocabulary for telescopic systems — Part 3: Terms for telescopic sights 141 –1 : 14 , Optics and photonics — Specifications for telescopic sights — Part 1: General- purpose in struments ISO 141 –2 : 14 , Optics and photonics — Specifications for telescopic sights — Part 2: High- performance instruments 3 Terms and definitions For the purposes of this document, the terms and de finitions given in I S O 141 -1 a nd I S O 141 -3 apply Method of measurement of axial parallax 4.1 This Principle te s t me tho d de s c r ib e s the me a s u re me n t o f the a xial d i s t a nce b e t we e n the re tic le of a te l e s co p ic sight and an image, formed by the objective lens of this telescopic sight (where the reticle is in the first image plane) or by the objective lens and erecting system (where the reticle is in the second image © I S O – Al l ri gh ts re s e rve d ISO 14490-3 :2 016(E) plane) The distance between the reticle of the telescopic sight and image plane of the collimator reticle along the optical axis 4.2 p ′ax is expressed in dioptres (m−1 ) and meas ured with the au xil iar y telescop e Test arrangement 4.2 General Measurement of the axial parallax shall be carried out with the test arrangement shown in Figure It shal l b e p os s ible to adj us t the alignment of the col limator and the telescopic s ight relative to each other T his can b e achieved by adj us ting the col l imator and/or the telescopic s ight Key collimator filter telescopic sight reticle of collimator dioptric tester reticle of telescopic sight o bserver’ s eye image plane of collimator reticle illumination unit 10 reticle of dioptric tester Figure — Test arrangement for measuring axial parallax 4.2 Collimator T he col limator shal l have a useful diameter larger than the obj ec tive lens diameter of the telescopic sight under test and a focal length of at least ten times the diameter of the collimator lens The reticle of the collimator should have geometric features appropriate to assess the offset, e.g a cros s-hair T he a xial p os ition of this reticle shal l b e correc tly adj us ted to form an image at the s p eci fied parallax-free distance of the telescopic sight under test The illumination unit shall create a uniform brightness over the aperture of the collimator To avoid chromatic ab errations , a green 4.2 fi lter (approximately , 5 µm) shal l b e used Telescopic sight The telescopic sight and/or the collimator shal l be adj us ted relative to each other so that b oth optical a xes are p arallel and in such a p osition that the obj ec tive lens of the telescopic sight is completely illuminated The centre of the reticle of the telescopic sight shall be near the optical axis of the sight 4.2 Dioptric tester The dioptric tester shall have an aperture larger than the exit pupil of the telescopic sight and a magnifying p ower s ufficient to ens ure a precise meas urement (i e × to × 6) © ISO 01 – All rights reserved ISO 14490-3 :2 016(E) 4.3 Measurement procedure Set the dioptric tester to zero with its eyepiece adjusted to obtain a sharp image of its own reticle The eyepiece of the telescopic sight shall be focused on the reticle of the telescopic sight to obtain a sharp image while viewing through the dioptric tester For telescopic sights with fixed eyepiece, use the dioptric tester to focus on the reticle of the telescopic sight The dioptre setting of the dioptric tester shall be adjusted to obtain a sharp image of the collimator reticle The axial parallax in the image space, the dioptric tester p ′ax , shall be determined by the difference of the two readings on The uncertainty of measurement for p ′ax (expressed in m−1) shall not exceed Formula (1) : ,7 m 10 ⋅ D (1) ' where D ’ is the exit pupil diameter of the telescopic sight expressed in metres For exit pupil diameters larger than mm, the value in the formula shall be D ′ = mm The axial parallax in the object space, p ax, is calculated as given in Formula (2) : p ax Γ2 where Γ is the magnifying power of the telescopic sight under test p ax = NOTE ' (2) The image quality of the test setup (including the telescopic sight under test) in fluences the measurement error 4.4 Test report A test report shall be presented and shall include the general information speci fied in Clause 10 and the result of the test as speci fied in Method of measurement of parallax 5.1 Principle This method describes the determination of the angular deviation between the aiming lines for on-axis and off-axis observation NOTE For exit pupil diameters of approximately mm or less, only the test method for axial parallax is appropriate 5.2 5.2 Test arrangement General Measurement of the parallax shall be carried out with the test arrangement shown in Figure It shall be possible to adjust the alignment of the collimator and the telescopic sight relative to each other This can be achieved by adjusting the collimator and/or the telescopic sight © ISO 01 – All rights reserved ISO 14490-3 :2 016(E) d Key ilter collimator f telescopic sight reticle of collimator light stop, off-axis auxiliary telescope observer’s eye reticle of telescopic sight illumination unit 10 reticle of auxiliary telescope Figure — Test arrangement for measuring parallax 5.2 Collimator The collimator shall have a useful diameter larger than the objective lens diameter of the telescopic sight under test and a focal length of at least ten times the diameter of the collimator lens The reticle of the collimator should have geometric features appropriate to assess the offset, e.g a cross-hair The axial position of this reticle shall be correctly adjusted to form an image at the speci fied parallax-free distance of the telescopic sight under test The illumination unit shall create a uniform brightness over the aperture of the collimator To avoid chromatic aberrations, a green filter (approximately 0,55 µm) shall be used 5.2 Telescopic sight The telescopic sight and/or the collimator shall be adjusted relative to each other so that both optical axes are parallel and in such a position that the objective lens of the telescopic sight is completely illuminated The centre of the reticle of the telescopic sight shall be near the optical axis of the sight 5.2 Light stop d, in millimetres, (see Figure 2) magnifying power of the telescopic sight under test The light stop shall have a diameter, of d = (1,2 ± 0,1) Γ where Γ is the The light stop shall be adjustable in a horizontal direction over the whole diameter of the entrance pupil of the telescopic sight 5.2 Auxiliary telescope The auxiliary telescope shall have an aperture larger than the exit pupil of the telescopic sight and a magni fication sufficient to ensure a precise measurement The auxiliary telescope reticle shall have a scale in minutes of arc on its horizontal axis, with subdivisions of at most minutes of arc (MOA) The auxiliary telescope shall be focused to in finity © ISO 01 – All rights reserved ISO 14490-3 :2 016(E) 5.3 Measurement procedure The eyepiece of the telescopic sight shall be focused on the reticle of the telescopic sight to obtain a sharp image while viewing through the auxiliary telescope Adjust the light stop to two opposite positions, so that in each of them, its outer edge corresponds to the edge of the entrance pupil of the telescopic sight Use the auxiliary telescope to determine the change, α, in MOA, of the angular deviation between the images of the collimator reticle and the telescopic sight reticle in the two light stop positions (see Figure 3) α 23 Key telescopic sight reticle of telescopic sight image plane of collimator reticle α change, in MOA, of the angular deviation between the images of the collimator reticle and the telescopic sight reticle in the two light stop positions Figure — Explanation of measurement of quantity α The parallax p ′ in the image space is calculated as given in Formula (3): α p = ' (3) The maximum parallax in the object space p is calculated as given in Formula (4) : p= p Γ ' (4) Γ is the magnifying power of the telescopic sight under test where The uncertainty of measurement for p ′ shall not exceed 1,0 MOA NOTE For practical purposes, the relations between parallax and axial parallax are given by the fol lowing formu lae: p =p ' p =p ' where ' ax ' ax D ' D ' , expressed in milliradians × , 438 , expressed in minutes of arc D ′ is the exit pupil diameter, expressed in millimetres © ISO 01 – All rights reserved ISO 14490-3 :2 016(E) 5.4 Test report A test report shall be presented and shall include the general information speci fied in result of the test as speci fied in C l au s e a nd the 5.3 Method of measurement of eye relief range 6.1 Principle This method describes the determination of that eye position range along the optical axis of a telescopic sight, which still allows observation of the full field of view For this method, a mean daylight eye pupil of mm in diameter is assumed For an illustration of eye relief range, see g i ve n a s “ 6.2 6.2 d to d F i g u re For documentation purposes, the eye relief range is ” ma x Test arrangement General Measurement of the eye relief range shall be carried out with the test arrangement shown in F i g u re It shall be possible to adjust the alignment of the collimator and the telescopic sight relative to each other This can be achieved by adjusting the collimator and/or the telescopic sight 6.2 Collimator The collimator shall have a useful diameter larger than that of the objective lens of the telescopic sight u n de r te s t a n d a fo c a l le n g th o f at le a s t te n ti me s the d i a me te r o f the c o l l i m ato r le n s T he c o l l i m ato r s h a l l h ave t wo p o i nt- s h ap e d l i ght s o u rce s p o s i tio ne d i n the fo c a l p l a ne o f the c o l l i m ato r In the case of a telescopic sight without parallax adjustment, the two point-shaped light sources shall be positioned in such way that their images appear in the parallax-free distance These light sources shall be adjustable symmetrically about the optical axis in correspondence to the field of view of the te le s c o p ic s i ght To avoid chromatic aberration, a green filter (approximately 0,55 µm) shall be used 6.2 Telescopic sight T he re ti cle o f the te le s c o p i c s i ght s h a l l b e ne a r the o p tic a l a x i s o f the s i gh t T he te le s co p ic s i gh t s h a l l b e adjustable relative to the collimator around two mutually orthogonal axes lying in a plane perpendicular to the o p tic a l a x i s 6.2.4 Measuring magnifier The measuring magni fier should have a magnifying power of approximately ten times and a reticle with a g radu atio n o f ,1 m m T he g radu ate d s i de o f the re ti cle i s p o s i tio ne d a s clo s e to the d i ffu s i n g s u r face o f the s c re e n a s p o s s ib le The optical axis of the measuring magni fier is positioned parallel to the optical axis of the telescopic sight and adjustable in the axial direction © I S O – Al l ri gh ts re s e rve d ISO 14490-3 :2 016(E) Dimensions in millimetres A B C A B C d d med d m ax 0,5 C-C ,5 B-B 0,5 ,5 A-A Key collimator telescopic sight diffusing screen glass with scale measuring magni fier NOTE Sectional views A-A, B-B and C-C show appearance of ray bundles at distances dmin , dmed and dmax , respectively Figure — Test arrangement for measuring eye relief range 6.3 Measurement procedure Adjust the distance between the two light sources of the collimator corresponding to the field of view of the telescopic sight under test Align the telescopic sight so that the edge line of the field of view corresponds with the images of the two light sources Move the measuring magni fier, starting from a position close to the telescopic sight, along the optical axis until the inner edges of the two ray bundles are at a distance of mm (see Figure 4, section A-A) In this position, 0,5 mm of the meridional extension of each of the two ray bundles are covered by a mean daylight eye pupil of mm in diameter This position represents the lower limit of the eye relief range Continue moving the measuring magni fier along the optical axis until the inner edges of the two ray bundles again are at a distance of mm (see Figure 4, section C- C ) This position represents the upper limit of the eye relief range © ISO 01 – All rights reserved ISO 14490-3 :2 016(E) The values for the upper and lower limits of the eye relief range are given by the distances in millimetres fro m the ve r te x of the las t o p tic a l s u r fac e of the te l e s c o p ic measuring magni fier in both of the above de fined positions s i gh t to the g radu ate d s u r fac e of the The uncertainty of measurement shall be less than 0,4 mm for each distance and less than 0,8 mm for the eye relief range 6.4 Test report A test report shall be presented and shall include the general information speci fied in result of the test as speci fied in C l au s e a nd the 6.3 Method of measurement of reticle tracking 7.1 Principle This method describes how to check the movement of the aiming mark over the total adjustment range i n re l atio n to the re tic l e a xe s 7.2 7.2 Test arrangement General The test equipment consists of a collimator and a fixture for the telescopic sight under test in front of the collimator The telescopic sight shall be adjustable relative to the collimator around two mutually orthogonal axes lying in a plane perpendicular to the optical axis In o rde r to avo id m i s a l i g n me n t b e t we e n the c o l l i m ato r a nd the te l e s c o p ic s i gh t whe n c o n tro l s on the latter are actuated, it may be advisable to keep the telescopic sight rigidly mounted in a sturdy stationary fixture while making the adjustments necessary to accomplish correct alignment by moving the c o l l i m ato r 7.2 Collimator The collimator shall have a useful diameter larger than that of the objective lens of the telescopic sight u n de r te s t a n d a fo c a l l e n g th o f at l e a s t te n ti m e s the d i a m e te r o f the c o l l i m ato r l e n s The axial position of this reticle shall be correctly adjusted to form a virtual image at the speci fied parallax-free distance of the telescopic sight under test T he re ticle o f the col l i m ato r s h a l l b e a s s ho wn i n Fi gu re The field of view of the collimator shall be greater than or equal to the total reticle adjustment range of the te l e s c o p ic s i gh t u n de r te s t © I S O – Al l ri gh ts re s e rve d ISO 14490-3 :2 016(E) 2α 2α Key α an gu l ar to l e ran ce , i n d e gre e s Figure — Reticle of collimator 7.3 Test procedure Adjust the position of the telescopic sight so that the axes of the two reticles are parallel and the aiming m a rk co r re s p o n d s to the c e n tre o f the co l l i m ato r re ti cle When adjusting the line of sight of the test specimen throughout its speci fied range in vertical direction only, the aiming mark shall not fall outside the speci fied angular tolerance Repeat the above procedure for the horizontal adjustment range The uncertainty of measurement of α 7.4 s h a l l no t e xce e d , ° Test report A test report shall be presented and shall include the general information speci fied in result of the test as speci fied in C l au s e a nd the Method of measurement of line of sight shift due to zooming 8.1 Principle This method is only applicable for test specimens with a reticle in the second image plane Due to the tolerances of the mechanical parts of the test specimen, the line of sight may vary while z o o m i n g To de te r m i ne the de vi atio n i n p o i n ti n g o f the l i ne o f s i gh t due to z o om i ng , the fo l lo w i n g te s t me tho d s ho u ld b e ap p l ie d 8.2 8.2 Test arrangement General M e a s u re me n t o f the l i ne o f s i ght s h i ft due to zo oming shal l be c a rrie d o u t w i th the te s t a r n ge me nt s ho w n i n F i g u re The measuring set-up consists of a light source, an adjustable object-side collimator with a test target, a rigid test specimen mounting, and an auxiliary telescope © I S O – Al l ri gh ts re s e rve d ISO 14490-3 :2 016(E) It shall be possible to adjust the alignment of the collimator and the telescopic sight relative to each other This can be achieved by adjusting the collimator and/or the telescopic sight In order to avoid misalignment between the collimator and the telescopic sight when controls on the latter are actuated, it may be advisable to keep the telescopic sight rigidly mounted in a sturdy stationary fixture while making the adjustments necessary to accomplish correct alignment by moving the collimator 34 Key illumination unit condenser scattering plate f test target adjustable collimator lens telescopic sight auxiliary telescope ilter NOTE The object-side collimator is described by the keys to Figure — Test arrangement for line of sight shift due to zooming The light source consists of an incandescent lamp, a condenser, a light scattering plate and a filter The light scattering plate should be a diffusing plate To avoid chromatic aberration, a green filter (approximately 0,55 µm) shall be used The adjustable object-side collimator consists of a test target and a collimator lens When used at its in finity setting, the test target shall be in the focal plane of the collimator lens To simulate different object distances, the distance between the collimator lens and the test target should be adjustable The collimator shall have a useful diameter larger than that of the objective lens of the telescopic sight under test and a focal length of at least ten times the diameter of the collimator lens The test target should consist of a circle, a vertical and a horizontal line with tick marks according to Figure The diameter of the circle should be chosen according to the speci fications given in I SO 141 -1 and I SO 141 -2 E XAMPLE The diameter of the circle should subtend an angle of 0,4 mrad (1 ,4’ ) , which corresponds to a diameter of cm at 10 m The tick marks should correspond to a distance of 10 cm at 10 m EXAMPLE Alternatively, the diameter of the circle should subtend an angle of 2’ for test specimens with a click s top dis tance in units of minutes of arc (MOA) The tick marks should then correspond to an angle of 5’ The tick marks are not important for this measurement method, but can be convenient for related measurements like click s top distances or the like 10 © ISO 01 – All rights reserved ISO 14490-3 :2 016(E) Figure — Test target 8.2 Test specimen mounting The mounting shall be very rigid to ensure a stable pointing during the measurement procedure, especially when turning the zooming facility of the test specimen The pointing stability of the test specimen’s reticle while touching the test specimen shall be sufficient to ful fil the requirements according to ISO 14135-1:2014, Table and ISO 14135-2:2014, Table 2, respectively 8.2 Auxiliary telescope The auxiliary telescope shall have an aperture larger than the exit pupil of the telescopic sight and a magnifying power sufficient to ensure a precise measurement It shall be focused to in finity 8.3 Test procedure 8.3 Preparation of the test assembly The adjustable collimator shall be set to a position equivalent to the parallax-free distance of the test specimen, i.e at 100 m This setting gives a virtual image of the test target in the speci fied distance The test specimen shall be set initially to its lowest magnifying power setting The adjustment range of the reticle position shall be set about its centre position The eyepiece of the test specimen shall be fo c u s e d o n the re ti cle o f the te le s c o p ic s i gh t to o b ta i n a s h a r p i m a ge the re o f wh i le vi e w i n g th ro u gh the auxiliary telescope The test specimen shall be adjusted very carefully to align the centre of its reticle w i th the i m a ge o f the ce n tre o f the te s t t a r ge t’s c i rc le 8.3 Determination of the measurement values With the two centres initially exactly coinciding, the zooming facility of the test specimen shall be turned towards its highest magnifying power During the zooming movement, a possible position deviation of the two centres shall be watched carefully The position of the reticle should remain stable T he p o s i tio n o f the i m a ge o f the te s t ta rge t m i gh t mo ve i n re l atio n to the re ti cle The largest distance between the centres of the test specimen’s reticle in any zoom position shall be re c o rde d Fo r i l lu s trati o n , b e t we e n the see F i g u re te s t s p e c i me n’s The small grey circles in re tic le a nd the i m a ge o f the F i g u re re p re s e n t te s t ta rge t a lo n g the the re l ati ve d a s he d l i ne mo ve me nt fo r va r io u s magnifying power settings The largest difference in this example is about cm (diameter of the surrounding dotted circle) For demonstration purposes, the movement is greatly exaggerated When watching the image during zooming, the test target’s image is being magni fied, while the diameter of the reticle (grey circle) remains stable because of its position in the second image plane of the te s t s p e c i me n © I S O – Al l ri gh ts re s e rve d 11 ISO 14490-3 :2 016(E) Instead of showing the magni fication and the movement of the test target’s image, opposite situation as a decreasing and a movement of the reticle (grey circles) to give a clearer drawing F i g u re i l lu s trate s the NO TE T h e nu m b e r s to s ho w the o r d e r o f m e a s u r e m e n t Figure — Example of a movement of the test specimen’s reticle relative to the centre of the test target as seen through the auxiliary telescope (normalized representation of the test target) 8.4 Precision of the measurement The uncertainty of the measurement shall ful fil the requirements according to ISO 14135-1 for general p u r p o s e i n s tr u me n ts a n d I S O 141 -2 fo r h i gh p e r fo r m a nce i n s tr u me n ts 8.5 Test report A test report shall be presented and shall include the general information speci fied in result of the test as speci fied in C l au s e a nd the 8.3 Method of measurement of line of sight shift due to focusing 9.1 Principle This method is only applicable for test specimen with the capability of focusing the object on the reticle The position of the reticle can be in any focal plane of the telescopic sight (first or/and second plane) NOTE If the reticle is in the second plane, then for different magnifying powers, the value of line of sight shift due to fo c u s i n g c a n b e d i ffe r e n t Due to the tolerances of the mechanical and optical parts of the test specimen, the line of sight may vary wh i le fo c u s i n g To de te r m i ne the de v i atio n i n p o i n ti n g o f the l i ne o f s i gh t due to fo c u s i n g , the fo l lo w i n g te s t me tho d s ho u ld b e ap p l i e d 9.2 9.2 Test arrangement General M e a s u re me n t o f the l i ne o f s i gh t s h i ft due to fo c u s i n g shal l be c a rrie d o u t w i th the te s t a r n ge me n t s ho w n i n F i g u re The measuring set-up consists of an adjustable object-side collimator with a test target, a rigid test specimen mounting, and an auxiliary telescope It shall be possible to adjust the alignment of the collimator and the telescopic sight relative to each other This can be achieved by adjusting the collimator and/or the telescopic sight 12 © I S O – Al l ri gh ts re s e rve d ISO 14490-3 :2 016(E) In o rde r to avo i d m i s a l i g n me n t b e t we e n the c o l l i m ato r a nd the te le s c o p i c s i ght whe n c o ntro l s on the latter are actuated, it may be advisable to keep the telescopic sight rigidly mounted in a sturdy stationary fixture while making the adjustments necessary to accomplish correct alignment by moving the c o l l i m ato r 10 Key adjustable collimator lens adjustable objective lens i l l u m i n ati o n u n i t co n d e n s e r s catte ri n g p l ate te l e s co p i c s i gh t re ti cl e o f te l e s co p i c s i gh t filter te s t targe t NOTE 10 auxiliary telescope The object-side collimator is described by the keys to Figure — Test arrangement for line of sight shift due to focusing 9.2 Collimator The adjustable object-side collimator consists of a light source, a test target and a collimator lens When used at its in finity setting, the test target shall be in the focal plane of the collimator lens To simulate different object distances, the distance between the collimator lens and the test target should be adjustable, in a range at least equal to the focusing system adjustment range of the te l e s c o p i c s i g h t u n d e r te s t The collimator shall have line of sight stability while focusing well above the stability of the test specimen The collimator shall have a useful diameter larger than that of the objective lens of the te le s c o p i c s i ght u n de r te s t a n d i t s ho u ld h ave a fo c a l l e n g th s u i tab le fo r re tic le e n g ravi n g NO TE T h e r e c o m m e n d e d fo c a l l e n g th i s i n the o r d e r o f 0 m m The light source consists of an incandescent lamp, a condenser, a light scattering plate and a filter The light scattering plate should be a diffusing plate To avoid chromatic aberration, a green filter (approximately 0,55 µm) shall be used T he te s t t a r ge t s ho u ld s i s t of a nu mb e r of c i rc le s , a ve r tic a l a nd a ho r i z o nt a l l i ne acco rd i n g to F i g u re T he nu mb e r a nd the d i a me te r o f the c i rcle s s ho u ld b e cho s e n acc o rd i n g to the fo c u s i n g n ge a n d p e r fo r m a nce c l a s s o f the te le s co p ic s i ght © I S O – Al l ri gh ts re s e rve d 13 ISO 14490-3 :2 016(E) Figure 10 — Test target 9.2 Telescopic sight T he mounting shal l b e ver y rigid to ens ure a s table p ointing during the meas urement pro cedure, es p ecial ly when turning the focus ing faci lity of the tes t s p ecimen T he p ointing of the tes t s p ecimen’s re tic le wh i le to uch i n g the te s t s p e c i me n s h a l l b e s tab le 9.2 Auxiliary telescope T he au xi l iar y telescop e shal l have an ap er ture not les s than mm and a magni fying p ower s ufficient to ens ure a precise meas urement I t shal l b e fo cused to in finity 9.3 Test procedure 9.3 Preparation of the test assembly T he adj us table col l imator shal l always b e set to a p os ition equivalent to the p aral la x-free dis tance in the adj us tment range of the telescopic s ight under tes t T his setting gives a vir tual image of the tes t target in the s p eci fied dis tance T he fo c u s i ng faci l ity of the tes t s p ec imen shal l b e s et i n itial ly at the larges t di s tance to the obj ec t plane, us ual ly s et to in fi n ity T he re ticle shal l b e s et to the centre p o s ition of its adj u s tment range to avoid s ys tematic errors due to an off-a xi s meas u rement T he correc t p o s ition c an b e proved b y ro tating the s ight b y ° T he eyepie ce of the tes t s p eci men shal l b e fo c u s ed on the reticle of the teles copic s ight to ob tai n a shar p i mage thereof wh i le viewi ng through the au xi l iar y teles cop e T he tes t s p e ci men shal l b e adj us ted ver y carefu l ly to al ign the centre of its reticle with the i mage of the centre of the tes t t a r ge t ’s c i rc l e s 9.3 Determination of the measurement values T hen, the adj us table col l imator shal l b e set to a p os ition equivalent to the closes t p aral la x-free dis tance of the adj us tment range of the telescopic s ight With the two centres initial ly exac tly coinciding, the fo cus ing faci lity of the tes t s p ecimen shal l b e tu r ne d to wa rd s its clo s e s t p a l l a x- fre e re tic le s ho u ld re m a i n s t ab le d i s ta nce D uring the fo c u s i n g mo ve me n t, the p o s i tio n o f the T he p o s i tio n o f the i m a ge o f the te s t t a r ge t m i gh t mo ve i n re l atio n to the reticle T he rotation direc tion of the fo cus ing faci lity shou ld not b e reversed during the meas urement T he a n g u l a r d i ffe re nce b e t we e n the t wo ce n tre s s h a l l b e re c o rde d at the clo s e s t d i s ta nc e 9.4 Precision of the measurement T he uncer tainty of the meas urement shal l ful fil the s p eci fications 14 © I S O – Al l ri gh ts re s e rve d