ISO 14490-1:2005

Optics and optical instruments — Test methods for telescopic systems — Part 1: Test methods for basic characteristics

ISO 14490-1:2005 specifies the test methods for the determination of the following basic characteristics of telescopic systems and observational telescopic instruments: angular magnification; entrance pupil diameter; exit pupil diameter and eye relief; angular field of view in the object space; angular field of view in the image space; angular field of view in the object space for spectacle wearers; collimation of the bundle of rays emergent from the eyepiece; image rotation; closest distance of observation.

Optique et instruments d'optique — Méthodes d'essai pour systèmes télescopiques — Partie 1: Méthodes d'essai des caractéristiques fondamentales

General Information

• Status: Published
• Publication Date: 24-Oct-2005
• 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: 9093 - International Standard confirmed
• Completion Date: 20-Oct-2021

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14490-1
First edition
2005-10-15

Optics and optical instruments — Test
methods for telescopic systems —
Part 1:
Test methods for basic characteristics
Optique et instruments d'optique — Méthodes d'essai pour systèmes
télescopiques —
Partie 1: Méthodes d'essai des caractéristiques fondamentales




Reference number
ISO 14490-1:2005(E)
©
ISO 2005

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ISO 14490-1:2005(E)
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ii © ISO 2005 – All rights reserved

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ISO 14490-1:2005(E)
Contents Page
Foreword. v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Method of measurement of the angular magnification.2
4.1 General.2
4.2 Test arrangement.2
4.3 Procedure .3
4.4 Determination of results .3
4.5 Test report .3
5 Method of measurement of the entrance pupil diameter.3
5.1 General.3
5.2 Test arrangement.3
5.3 Procedure .4
5.4 Determination of results .4
5.5 Test report .4
6 Method of measurement of the exit pupil diameter and eye relief .4
6.1 General.4
6.2 Test arrangement.5
6.3 Procedure .5
6.4 Determination of results .5
6.5 Test report .6
7 Method of measurement of the angular field of view in the object space.6
7.1 General.6
7.2 Test arrangement.6
7.3 Procedure .6
7.4 Determination of results .7
7.5 Test report .7
8 Method of measurement of the angular field of view in the image space .7
8.1 General.7
8.2 Test arrangement.7
8.3 Procedure .8
8.4 Determination of results .9
8.5 Test report .9
9 Method of measurement of the angular field of view in the object space for spectacle
wearers .9
9.1 General.9
9.2 Test arrangement.9
9.3 Procedure .9
9.4 Determination of results .11
9.5 Test report .11
10 Method of measurement of the collimation of rays emergent from the eyepiece .11
10.1 General.11
10.2 Test arrangement.11
10.3 Procedure .12
10.4 Determination of results .12
10.5 Test report .12
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ISO 14490-1:2005(E)
11 Method of measurement of the image rotation. 12
11.1 General . 12
11.2 Test arrangement . 12
11.3 Procedure. 13
11.4 Determination of results. 13
11.5 Test report. 13
12 Method of determination of the closest distance of observation . 14
12.1 General . 14
12.2 Test arrangement . 14
12.3 Procedure. 14
12.4 Determination of results. 14
12.5 Test report. 14
13 General test report . 14

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ISO 14490-1:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 14490-1 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 4,
Telescopic systems.
ISO 14490 consists of the following parts, under the general title Optics and optical instruments — 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
The following part is under preparation:
⎯ Part 8: Test methods for night-vision devices

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INTERNATIONAL STANDARD ISO 14490-1:2005(E)

Optics and optical instruments — Test methods for telescopic
systems —
Part 1:
Test methods for basic characteristics
1 Scope
This part of ISO 14490 specifies the test methods for the determination of the following basic characteristics of
telescopic systems and observational telescopic instruments:
⎯ angular magnification (see Clause 4);
⎯ entrance pupil diameter (see Clause 5);
⎯ exit pupil diameter and eye relief (see Clause 6);
⎯ angular field of view in the object space (see Clause 7);
⎯ angular field of view in the image space (see Clause 8);
⎯ angular field of view in the object space for spectacle wearers (see Clause 9);
⎯ collimation of the bundle of rays emergent from the eyepiece (see Clause 10);
⎯ image rotation (see Clause 11);
⎯ closest distance of observation (see Clause 12).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 14132-1:2002, Optics and optical instruments — Vocabulary for telescopic systems — Part 1: General
terms and alphabetical indexes of terms in ISO 14132
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14132-1 apply.
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ISO 14490-1:2005(E)
4 Method of measurement of the angular magnification
4.1 General
In accordance with ISO 14132-1, the angular magnification Γ of a telescopic system is defined by the following
equation:
tan ww′ ′
Γ=≈ (1)
tan ww
where w and w′ are angles that the axes of conjugate beams make with the optical axis in the object space
and image space, respectively.
The method of measurement of the angular magnification is based on the measurement of the angular size of
an object placed in the field of view of a test specimen and that of its image.
4.2 Test arrangement
Measurement of the magnification shall be carried out with the angular test arrangement shown in Figure 1.
For systems for which the magnification is to be measured under a focus setting other than infinity, the
collimator scale shall be adjusted in order to form the image of the scale at the specified distance from the test
specimen.
The test arrangement shall be provided with a green optical filter to avoid any chromatism of the image. The
maximum transmittance of the filter shall be at a wavelength of about 0,55 µm.
As an optical angular measuring device, one of the following shall be used:
⎯ a telescope with a scale having divisions of known angular size;
⎯ a telescope with a micrometer eyepiece;
⎯ any other angle-measuring device which assures the required measurement precision.
The same method should be used for Galilean telescopes.

Key
1 light source 5 scale
2 condenser 6 collimator lens
3 filter 7 test specimen
4 diffusing plate 8 optical angle measuring telescope
Figure 1 — Test arrangement for measurement of the angular magnification
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ISO 14490-1:2005(E)
4.3 Procedure
–1
Before starting the measurements, adjust the eyepiece of the test specimen to 0 m and focus the test
specimen onto an infinitely remote object.
Determine the number of telescope (8 in Figure 1) scale divisions covered by an integral number of collimator
scale (5 in Figure 1) image divisions produced by the test specimen.
If a telescope with a micrometer eyepiece is used, measure the angular size of the image of a part of the
collimator scale (5 in Figure 1) produced by the test specimen.
4.4 Determination of results
The magnification Γ that is to be found is defined as the ratio of the size of the image of the collimator scale
(5 in Figure 1) produced by the telescope to the size of the corresponding part of the collimator scale.
For the case in which a telescope with a micrometer eyepiece is used
na⋅
1
Γ = (2)
ma⋅
2
where
n is the number of divisions of the telescope (8 in Figure 1) scale that corresponds to the number of
divisions m of the collimator scale (5 in Figure 1) image;
a is the scale division value of the measuring telescope scale;
1
a is the scale division value of the collimator scale.
2
The uncertainty of magnification shall be less than one third of the maximum deviation from the nominal value
specified in the relevant specification standard. For calculation of the magnification difference between the
telescopes of a binocular having a magnification of 6× or more, this tolerance shall be reduced by half.
4.5 Test report
A test report shall be presented and shall include the general information specified in Clause 13 and the result
of the test as specified in 4.4.
5 Method of measurement of the entrance pupil diameter
5.1 General
The method of measurement of the entrance pupil diameter D is based on viewing a reticle which is placed
near the entrance pupil through the test specimen and reading off the linear size of the entrance pupil
diameter.
5.2 Test arrangement
For a schematic representation of the test arrangement see Figure 2.
The test arrangement shall be provided with a green optical filter to avoid any chromatism of the image. The
maximum transmittance of the filter should be at a wavelength of about 0,55 µm.
The same method shall be used for Galilean telescopes.
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ISO 14490-1:2005(E)

Key
1 light source 5 collimator lens 9 exit pupil; reticle optional
2 condenser 6 reticle 10 magnifier or microscope
3 filter 7 test specimen 11 scale
4 pinhole 8 intermediate image
Figure 2 — Test arrangement for the measurement of the entrance pupil diameter
5.3 Procedure
To measure the entrance pupil diameter, set a reticle with a fixed scale (or two adjustable knife edges)
immediately in front of the test specimen's objective lens.
Illuminate the reticle marks (or knife edges) with a collimator. Position a field stop, whose apparent size may
not exceed three arc minutes, in the focal plane of the collimator.
Use a microscope or a magnifier behind the eyepiece of the test specimen. Determine which two reticle marks
are coincident with the edges of the entrance pupil (or adjust the knife edges to
...