ISO 14490-4:2005

Optics and optical instruments — Test methods for telescopic systems — Part 4: Test methods for astronomical telescopes

ISO 14490-4:2005 is applicable to amateur astronomical telescopes. For general optical test methods of telescopic systems see ISO 14490-1.

Optique et instruments d'optique — Méthodes d'essai pour systèmes télescopiques — Partie 4: Méthodes d'essai pour télescopes astronomiques

General Information

• Status: Published
• Publication Date: 03-Nov-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 14490-4
First edition
2005-11-01

Optics and optical instruments — Test
methods for telescopic systems —
Part 4:
Test methods for astronomical
telescopes
Optique et instruments d'optique — Méthodes d'essai pour systèmes
télescopiques—
Partie 4: Méthodes d'essai pour télescopes astronomiques




Reference number
ISO 14490-4:2005(E)
©
ISO 2005

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ISO 14490-4:2005(E)
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ISO 14490-4:2005(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
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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 14490-4 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

© ISO 2005 – All rights reserved iii

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INTERNATIONAL STANDARD ISO 14490-4:2005(E)

Optics and optical instruments — Test methods for telescopic
systems —
Part 4:
Test methods for astronomical telescopes
1 Scope
This part of ISO 14490 is applicable to amateur astronomical telescopes.
For general optical test methods of telescopic systems see ISO 14490-1.
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 8596, Ophthalmic optics — Visual acuity testing — Standard optotype and its presentation
ISO 14132-1:2002, Optics and optical instruments — Vocabulary for telescopic systems — Part 1: General
terms and alphabetical indexes of terms in ISO 14132
ISO 14132-4:2002, Optics and optical instruments — Vocabulary for telescopic systems — Part 4: Terms for
astronomical telescopes
ISO 14490-1:2005, Optics and optical instruments — Test methods for telescopic systems — Part 1: Test
methods for basic characteristics
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14132-1 and ISO 14132-4 apply.
4 Optical test methods for astronomical telescopes
Typical test methods are shown here, and other similar methods are acceptable.
4.1 Clear aperture of objective
The clear aperture of the objective shall be measured by one of the following methods.
a) Measure the unobstructed diameter of the objective lens of refracting telescopes and finder telescopes or
that of the main mirror of reflecting telescopes by means of an appropriate linear measuring instrument.
b) Set the focus of the optical system of the telescope or finder telescope to infinity using a dioptric tester.
Set a bundle of parallel rays at zero incidence angle using a collimator on the eyepiece side, project the
exit bundle of rays from the objective onto a screen perpendicular to the optical axis and measure its
diameter.
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ISO 14490-4:2005(E)
c) Using a piece of ground glass let diffuse light be incident on the eyepiece side of the telescope or the
finder telescope, and measure the minimum value of the aperture of the objective by using a travelling
microscope parallel to the optical axis in object space, which can be moved across the diameter of the
objective.
4.2 Focal lengths of objective and eyepiece
The test methods for the focal lengths of objective and eyepiece shall be as given in 4.2.1 or 4.2.2.
4.2.1 Focal length of objective lens and eyepiece (nodal slide method)
Refer to Figure 1. Arrange the rotary table (item 8 in Figure 1) (nodal slide stand), so that the axis of rotation is
perpendicular to the optical axis of the collimator lens (item 3) on an optical bench (item 6). Place a reticle
(item 2) at the focal plane of the collimator. On the rotary table, a slide stand (item 7) i
...