ISO 14490-3:2016

Optics and photonics — Test methods for telescopic systems — Part 3: Test methods for telescopic sights

ISO 14490-3:2016 specifies test equipment and test procedures for determination of the following optical characteristics of telescopic sights: - axial parallax; - parallax; - eye relief range; - reticle tracking; - line of sight shift due to zooming; - line of sight shift due to focusing.

Optique et photonique — Méthodes d'essai pour systèmes télescopiques — Partie 3: Méthodes d'essai pour viseurs de tir

General Information

• Status: Withdrawn
• Publication Date: 17-Feb-2016
• Withdrawal Date: 17-Feb-2016
• ICS: 37.020 - Optical equipment
• Technical Committee: ISO/TC 172/SC 4 - Telescopic systems
• Drafting Committee: ISO/TC 172/SC 4 - Telescopic systems
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 23-Mar-2021

Relations

• Revised: ISO 14490-3:2021 - Optics and photonics — Test methods for telescopic systems — Part 3: Test methods for telescopic sights
• Effective Date: 23-Apr-2020
• Revises: ISO 14490-3:2004 - Optics and optical instruments — Test methods for telescopic systems — Part 3: Test methods for telescopic sights
• Effective Date: 06-Jul-2012

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14490-3
Second edition
2016-02-15
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: Méthodes d’essai pour viseurs de tir
Reference number
ISO 14490-3:2016(E)
©
ISO 2016

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ISO 14490-3:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, 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 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2016 – All rights reserved

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ISO 14490-3:2016(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Method of measurement of axial parallax . 1
4.1 Principle . 1
4.2 Test arrangement . 2
4.2.1 General. 2
4.2.2 Collimator . 2
4.2.3 Telescopic sight . 2
4.2.4 Dioptric tester . 2
4.3 Measurement procedure . 3
4.4 Test report . 3
5 Method of measurement of parallax . 3
5.1 Principle . 3
5.2 Test arrangement . 3
5.2.1 General. 3
5.2.2 Collimator . 4
5.2.3 Telescopic sight . 4
5.2.4 Light stop . 4
5.2.5 Auxiliary telescope . 4
5.3 Measurement procedure . 5
5.4 Test report . 6
6 Method of measurement of eye relief range . 6
6.1 Principle . 6
6.2 Test arrangement . 6
6.2.1 General. 6
6.2.2 Collimator . 6
6.2.3 Telescopic sight . 6
6.2.4 Measuring magnifier . 6
6.3 Measurement procedure . 7
6.4 Test report . 8
7 Method of measurement of reticle tracking . 8
7.1 Principle . 8
7.2 Test arrangement . 8
7.2.1 General. 8
7.2.2 Collimator . 8
7.3 Test procedure . 9
7.4 Test report . 9
8 Method of measurement of line of sight shift due to zooming . 9
8.1 Principle . 9
8.2 Test arrangement . 9
8.2.1 General. 9
8.2.2 Test specimen mounting .11
8.2.3 Auxiliary telescope .11
8.3 Test procedure .11
8.3.1 Preparation of the test assembly .11
8.3.2 Determination of the measurement values .11
8.4 Precision of the measurement .12
8.5 Test report .12
9 Method of measurement of line of sight shift due to focusing .12
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ISO 14490-3:2016(E)

9.1 Principle .12
9.2 Test arrangement .12
9.2.1 General.12
9.2.2 Collimator .13
9.2.3 Telescopic sight .14
9.2.4 Auxiliary telescope .14
9.3 Test procedure .14
9.3.1 Preparation of the test assembly .14
9.3.2 Determination of the measurement values .14
9.4 Precision of the measurement .14
9.5 Test report .15
10 General test report .15
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ISO 14490-3:2016(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 1. 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 2 (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 identified 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 specific 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 and photonics, Subcommittee SC 4,
Telescopic systems.
This second edition cancels and replaces the first edition (ISO 14490-3:2004), which has been
technically revised with the following changes:
a) Clause 9 “Method of measurement of line of sight shift due to focusing” was added;
b) the term “magnification” was replaced by “magnifying power” in various instances.
ISO 14490 consists of the following parts, under the general title Optics and photonics — Test methods
for telescopic systems:
— Part 1: Test methods for basic characteristics
— Part 2: Test methods for binocular systems
— Part 3: Test methods for telescopic sights
— Part 4: Test methods for astronomical telescopes
— Part 5: Test methods for transmittance
— Part 6: Test methods for veiling glare index
— Part 7: Test methods for limit of resolution
— Part 8: Test methods for night-vision devices
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INTERNATIONAL STANDARD ISO 14490-3:2016(E)
Optics and photonics — Test methods for telescopic
systems —
Part 3:
Test methods for telescopic sights
1 Scope
This part of ISO 14490 specifies test equipment and test procedures for determination of the following
optical characteristics of telescopic sights:
— axial parallax;
— parallax;
— eye relief range;
— reticle tracking;
— line of sight shift due to zooming;
— line of sight shift due to focusing.
2 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.
ISO 14132–1, Optics and photonics — Vocabulary for telescopic systems — Part 1: General terms and
alphabetical indexes of terms in ISO 14132
ISO 14132–3, Optics and photonics — Vocabulary for telescopic systems — Part 3: Terms for telescopic sights
ISO 14135–1:2014, Optics and photonics — Specifications for telescopic sights — Part 1: General-
purpose instruments
ISO 14135–2:2014, 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 definitions given in ISO 14132-1 and ISO 14132-3 apply.
4 Method of measurement of axial parallax
4.1 Principle
This test method describes the measurement of the axial distance between the reticle of a telescopic
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
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ISO 14490-3:2016(E)

plane). The distance between the reticle of the telescopic sight and image plane of the collimator reticle
−1
along the optical axis p′ is expressed in dioptres (m ) and measured with the auxiliary telescope.
ax
4.2 Test arrangement
4.2.1 General
Measurement of the axial parallax shall be carried out with the test arrangement shown in Figure 1.
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.
1 23 4
Key
1 collimator 6 filter
2 telescopic sight 7 reticle of collimator
3 dioptric tester 8 reticle of telescopic sight
4 observer’s eye 9 image plane of collimator reticle
5 illumination unit 10 reticle of dioptric tester
Figure 1 — Test arrangement for measuring axial parallax
4.2.2 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 specified
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.
4.2.3 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.
4.2.4 Dioptric tester
The dioptric tester shall have an aperture larger than the exit pupil of the telescopic sight and a
magnifying power sufficient to ensure a precise measurement (i.e. ×3 to ×6).
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ISO 14490-3:2016(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, p′ , shall be determined by the difference of the two readings on
ax
the dioptric tester.
−1
The uncertainty of measurement for p′ (expressed in m ) shall not exceed Formula (1):
ax
27, m
(1)
62
10 ⋅ D '
where D’ is the exit pupil diameter of the telescopic sight expressed in metres.
For exit pupil diameters larger than 7 mm, the value in the formula shall be D′ = 7 mm.
The axial parallax in the object space, p , is calculated as given in Formula (2):
ax
p '
ax
p = (2)
ax
2
Γ
where Γ is the magnifying power of the telescopic sight under test.
NOTE The image quality of the test setup (including the telescopic sight under test) influences the
measurement error.
4.4 Test report
A test report shall be presented and shall include the general information specified in Clause 10 and the
result of the test as specified in 4.3.
5 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 2 mm or less, only the test method for axial parallax is
appropriate.
5.2 Test arrangement
5.2.1 General
Measurement of the parallax shall be carried out with the test arrangement shown in Figure 2.
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.
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ISO 14490-3:2016(E)

1 23 4
Key
1 collimator 6 filter
2 telescopic sight 7 reticle of collimator
3 auxiliary telescope 8 light stop, off-axis
4 observer’s eye 9 reticle of telescopic sight
5 illumination unit 10 reticle of auxiliary telescope
Figure 2 — Test arrangement for measuring parallax
5.2.2 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 specified
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.
5.2.3 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.
5.2.4 Light stop
The light stop shall have a diameter, d, in millimetres, (see Figure 2) of d = (1,2 ± 0,1) Γ where Γ is the
magnifying power of the telescopic sight under test.
The light stop shall be adjustable in a horizontal direction over the whole diameter of the entrance
pupil of the telescopic sight.
5.2.5 Auxiliary telescope
The auxiliary telescope shall have an aperture larger than the exit pupil of the telescopic sight and a
magnification 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 2 minutes of arc (MOA).
The auxiliary telescope shall be focused to infinity.
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ISO 14490-3:2016(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).
1
α
23
Key
1 telescopic sight
2 reticle of telescopic sight
3 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 3 — Explanation of measurement of quantity α
The parallax p′ in the image space is calculated as given in Formula (3):
α
p ' = (3)
2
The maximum parallax in the object space p is calculated as given in Formula (4):
p '
p = (4)
Γ
where Γ is the magnifying power of the telescopic sight under test.
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
following formulae:
D '
pp''= , expressed in milliradians
ax
2
D '
pp''=×3,438 , expressed in minutes of arc
ax
2
where D′ is the exit pupil diameter, expressed in millimetres.
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ISO 14490-3:2016(E)

5.4 Test report
A test report shall be presented and shall include the general information specified in Clause 10 and the
result of the test as specified in 5.3.
6 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 3 mm in diameter is assumed.
For an illustration of eye relief range, see Figure 4. For documentation purposes, the eye relief range is
given as “d to d ”.
min max
6.2 Test arrangement
6.2.1 General
Measurement of the eye relief range shall be carried out with the test arrangement shown in Figure 4.
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.
6.2.2 Collimator
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 collimator shall have two point-shaped light sources positioned in the focal plane of the collimator.
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
telescopic sight.
To avoid chromatic aberration, a green filter (approximately 0,55 µm) shall be used.
6.2.3 Telescopic sight
The reticle of the telescopic sight shall be near the optical axis of the sight. The telescopic sight shall be
adjustable relative to the collimator around two mutually orthogonal axes lying in a plane perpendicular
to the optical axis.
6.2.4 Measuring magnifier
The measuring magnifier should have a magnifying power of approximately ten times and a reticle with
a graduation of 0,1 mm. The graduated side of the reticle is positioned as close to the diffusing surface
of the screen as possible.
The optical axis of the measuring magnifier is positioned parallel to the optical axis of the telescopic
sight and adjustable in the axial direction.
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ISO 14490-3:2016(E)

Dimensions in millimetres
12
A B C
45
3
A BC

d
min

d
med

d
max
A-A B-B C-C
Key
1 collimator
2 telescopic sight
3 diffusing screen
4 glass with scale
5 measuring magnifier
NOTE Sectional views A-A, B-B and C-C show appearance of ray bundles at distances d , d and d ,
min med max
respectively.
Figure 4 — 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 magnifier, 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 2 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 3 mm in diameter.
This position represents the lower limit of the eye relief range.
Continue moving the measuring magnifier along the optical axis until the inner edges of the two ray
bundles again are at a distance of 2 mm (see Figure 4, section C-C).
This position represents the up
...