SIST EN ISO 12312-2:2015
(Main)Eye and face protection - Sunglasses and related eyewear - Part 2: Filters for direct observation of the sun (ISO 12312-2:2015)
Eye and face protection - Sunglasses and related eyewear - Part 2: Filters for direct observation of the sun (ISO 12312-2:2015)
The standard applies to all afocal (plano power) products intended for direct observation of the Sun, such as solar eclipse viewing. This standard does not apply to:
-afocal (plano power) sunglasses and clip-ons for general use intended for protection against solar radiation
- eyewear for protection against radiation from artificial light sources, such as those used in solaria
- eye protectors specifically intended for sports, for which separate standards are available (e.g. ski goggles or other types)
- sunglasses that have been medically prescript for attenuating solar radiation
Augen- und Gesichtsschutz - Sonnenbrillen und ähnlicher Augenschutz - Teil 2: Filter für die direkte Beobachtung der Sonne (ISO 12312-2:2015)
Dieser Teil der ISO 12312 gilt für alle Produkte ohne Korrekturwirkung (mit Nullgläsern), die für die direkte Beobachtung der Sonne vorgesehen sind, zum Beispiel bei der Betrachtung einer Sonnenfinsternis.
Informationen zur Verwendung von Filtern für die direkte Beobachtung der Sonne werden in Anhang A und Anhang B gegeben.
Dieser Teil der ISO 12312 gilt nicht für:
a) Sonnenbrillen ohne Korrekturwirkung (mit Nullgläsern) sowie Aufsteckscheiben für den allgemeinen Gebrauch bestimmt zum Schutz gegen Sonnenstrahlung;
b) Augenschutz gegen die Strahlung künstlicher Lichtquellen, z. B. von Solarien;
c) Augenschutzgeräte speziell für den Sport (z. B. Skibrillen oder andere Arten);
d) Sonnenbrillen, die aus medizinischen Gründen zur Dämpfung von Sonnenstrahlung verschrieben wurden;
e) Sonnenfilter mit Korrekturwirkung.
Protection des yeux et du visage - Lunettes de soleil et articles de lunetterie associés - Partie 2: Filtres pour l'observation directe du soleil (ISO 12312-2:2015)
L'ISO 12312-2:2015 s'applique à tous les produits afocaux (non correcteurs) destinés à l'observation directe du soleil, par exemple à l'observation d'une éclipse solaire.
L'ISO 12312-2:2015 ne s'applique pas à:
a) aux lunettes de soleil afocales (non correctrices) et aux contre-verres pour usage général, destinés à la protection contre le rayonnement solaire;
b) aux équipements de protection de l'?il contre le rayonnement des sources de lumière artificielle, telles que celles utilisées dans les solariums;
c) aux protecteurs d'yeux spécialement destinés aux activités sportives (par exemple, les masques de ski ou autres types);
d) aux lunettes de soleil ayant fait l'objet d'une prescription médicale et permettant d'atténuer le rayonnement solaire;
e) aux verres solaires correcteurs.
Varovanje oči in obraza - Sončna očala in sorodna oprema za varovanje oči - 2. del: Filtri za neposredno opazovanje sonca (ISO 12312-2:2015)
Ta standard velja za afokalne (brez korekcije) izdelke za neposredno opazovanje sonca, kot je npr. sončev mrk. Ta standard se ne uporablja za: – afokalna (brez korekcije) sončna očala in nastavke za sončna očala za splošno uporabo, ki so namenjeni zaščiti pred sončnim sevanjem; – oprema za varovanje oči pred sevanjem umetnih virov svetlobe, kot so viri, uporabljeni v solarijih; – zaščito za oči pri športih, za katero so na voljo drugi standardi (npr. smučarska očala ali druge vrste); – sončna očala, ki so bila zdravniško predpisana za slabitev vpliva sončnega sevanja.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 12312-2:2015
01-september-2015
9DURYDQMHRþLLQREUD]D6RQþQDRþDODLQVRURGQDRSUHPD]DYDURYDQMHRþL
GHO )LOWUL]DQHSRVUHGQRRSD]RYDQMHVRQFD ,62
Eye and face protection - Sunglasses and related eyewear - Part 2: Filters for direct
observation of the sun (ISO 12312-2:2015)
Augen- und Gesichtsschutz - Sonnenbrillen und ähnlicher Augenschutz - Teil 2: Filter für
die direkte Beobachtung der Sonne (ISO 12312-2:2015)
Protection des yeux et du visage - Lunettes de soleil et articles de lunetterie associés -
Partie 2: Filtres pour l'observation directe du soleil (ISO 12312-2:2015)
Ta slovenski standard je istoveten z: EN ISO 12312-2:2015
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
13.340.20 Varovalna oprema za glavo Head protective equipment
SIST EN ISO 12312-2:2015 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 12312-2:2015
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SIST EN ISO 12312-2:2015
EUROPEAN STANDARD
EN ISO 12312-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2015
ICS 13.340.20
English Version
Eye and face protection - Sunglasses and related eyewear - Part
2: Filters for direct observation of the sun (ISO 12312-2:2015)
Protection des yeux et du visage - Lunettes de soleil et Augen- und Gesichtsschutz - Sonnenbrillen und ähnlicher
articles de lunetterie associés - Partie 2: Filtres pour Augenschutz - Teil 2: Filter für die direkte Beobachtung der
l'observation directe du soleil (ISO 12312-2:2015) Sonne (ISO 12312-2:2015)
This European Standard was approved by CEN on 16 April 2015.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12312-2:2015 E
worldwide for CEN national Members.
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SIST EN ISO 12312-2:2015
EN ISO 12312-2:2015 (E)
Contents Page
European foreword .3
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 89/686/EEC Personal protective equipment .4
2
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SIST EN ISO 12312-2:2015
EN ISO 12312-2:2015 (E)
European foreword
This document (EN ISO 12312-2:2015) has been prepared by Technical Committee ISO/TC 94 “Personal
safety - Protective clothing and equipment” in collaboration with Technical Committee CEN/TC 85 “Eye
protective equipment” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2015, and conflicting national standards shall be withdrawn
at the latest by December 2015.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive.
For relationship with EU Directive, see informative Annex ZA, which is an integral part of this document.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 12312-2:2015 has been approved by CEN as EN ISO 12312-2:2015 without any modification.
3
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SIST EN ISO 12312-2:2015
EN ISO 12312-2:2015 (E)
Annex ZA
(informative)
Relationship between this European Standard and the Essential
Requirements of EU Directive 89/686/EEC Personal protective equipment
This European Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association to provide a means of conforming to Essential Requirements of the
New Approach Directive 89/686/EEC – Personal Protective Equipment.
Once this standard is cited in the Official Journal of the European Union under that Directive and has been
implemented as a national standard in at least one Member State, compliance with the clauses of this
standard given in Table ZA.1 confers, within the limits of the scope of this standard, a presumption of
conformity with the corresponding Essential Requirements of that Directive and associated EFTA regulations.
Table ZA.1 — Correspondence between this European Standard and Directive 89/686/EEC
Clause(s)/sub-clause(s) of this Essential Requirements (ERs) of Qualifying remarks/Notes
European Standard Directive 89/686/EEC
4.3.2 1.1.2.1. Highest level of protection ER not relevant for this type of
possible PPE
4.1, 4.1.1 1.1.2.2. Classes of protection ER not relevant for this type of
appropriate to different levels of risk PPE. There is only one level of
risk.
4.2.1, 4.3.1 1.2.1. Absence of risks and other ER not relevant for this type of
PPE. ER 1.2.1 should only be
‘inherent' nuisance factors
cited if there are risks of this type
that are not covered by 1.2.1.1 to
1.2.1.3
4.3.3 1.2.1.1. Suitable constituent Agreed
materials
4.3.3 1.2.1.2. Satisfactory surface Agreed
condition of all PPE parts in contact
with the user
4.2.1 1.2.1.3. Maximum permissible user Agreed
impediment
4.3.1, 4.3.2 1.3.1. Adaptation of PPE to user Agreed
morphology
5 1.4. Information supplied by the Agreed, but to be checked in
manufacturer detail
4.3.2 2.3. PPE for the face, eyes and ER 2.3 is relevant in this case (in
nd
respiratory tracts particular the 2 paragraph), but
is not addressed in 4.3.2. In fact
there is no clause in ISO 12312-2
that addresses optical neutrality.
4
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SIST EN ISO 12312-2:2015
EN ISO 12312-2:2015 (E)
Clause(s)/sub-clause(s) of this Essential Requirements (ERs) of Qualifying remarks/Notes
European Standard Directive 89/686/EEC
5 2.12. PPE bearing one or more ER 2.12 relates to markings on
identification or recognition marks the PPE itself. When looking at
directly or indirectly relating to clause 5, this seems to be more
health and safety about information that
accompanies the PPE (which is
covered by ER 1.4).
4.1, 4.1.1, 5 3.9.1. Non-ionizing radiation ER 3.9.1 is the key requirement in
this case. It is addressed by
clause 4.1, not clause 5. ER 3.9.1
has also consequences for the
marking, which are not yet
addressed in this standard.
It should also be considered if the
dimensions required in 4.3.2 are
sufficient to cover this risk.
WARNING: Other requirements and other EU Directives may be applicable to the product(s) falling within the
scope of this standard.
5
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SIST EN ISO 12312-2:2015
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SIST EN ISO 12312-2:2015
INTERNATIONAL ISO
STANDARD 12312-2
First edition
2015-06-15
Eye and face protection — Sunglasses
and related eyewear —
Part 2:
Filters for direct observation of the sun
Protection des yeux et du visage — Lunettes de soleil et articles de
lunetterie associés —
Partie 2: Filtres pour l’observation directe du soleil
Reference number
ISO 12312-2:2015(E)
©
ISO 2015
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SIST EN ISO 12312-2:2015
ISO 12312-2:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, 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
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Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
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SIST EN ISO 12312-2:2015
ISO 12312-2:2015(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements and associated test methods . 1
4.1 Transmittance . 1
4.1.1 General. 1
4.1.2 Uniformity of luminous transmittance . 2
4.2 Material and surface quality . 2
4.2.1 Requirements . 2
4.2.2 Test method . 2
4.3 Mounting . 2
4.3.1 General. 2
4.3.2 Dimensions . 2
4.3.3 Material quality . 3
5 Labelling . 3
Annex A (informative) Use of filters for direct observation of the sun . 4
[23]
Annex B (informative) Solar eclipse eye safety: User’s guide . 6
Bibliography .10
© ISO 2015 – All rights reserved iii
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SIST EN ISO 12312-2:2015
ISO 12312-2:2015(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 94, Personal safety — Protective clothing and
equipment, Subcommittee SC 6, Eye and face protection.
ISO 12312 consists of the following parts, under the general title Eye and face protection — Sunglasses
and related eyewear:
— Part 1: Sunglasses for general use
— Part 2: Filters for direct observation of the sun
iv © ISO 2015 – All rights reserved
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SIST EN ISO 12312-2:2015
INTERNATIONAL STANDARD ISO 12312-2:2015(E)
Eye and face protection — Sunglasses and related eyewear —
Part 2:
Filters for direct observation of the sun
1 Scope
This part of ISO 12312 applies to all afocal (plano power) products intended for direct observation of the
sun, such as solar eclipse viewing.
Information on the use of filters for direct observation of the sun is given in Annex A and Annex B.
This part of ISO 12312 does not apply to the following:
a) afocal (plano power) sunglasses and clip-ons for general use intended for protection against
solar radiation;
b) eyewear for protection against radiation from artificial light sources, such as those used in solaria;
c) eye protectors specifically intended for sports (e.g. ski goggles or other types);
d) sunglasses that have been medically prescribed for attenuating solar radiation;
e) prescription sunglass lenses.
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 12311:2013, Personal protective equipment — Test methods for sunglasses and related eyewear
ISO 4007, Personal protective equipment — Eye and face protection — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and the definitions given in ISO 4007 apply.
4 Requirements and associated test methods
4.1 Transmittance
4.1.1 General
The transmittance requirements of filters for the direct observation of the sun are given in Table 1.
Transmittance values shall be measured or calculated at the boxed centre of the filter for normal
incidence, as described in ISO 12311:2013, 7.1.1, 7.1.2, 7.3.2, 7.3.3, and 7.5.
© ISO 2015 – All rights reserved 1
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SIST EN ISO 12312-2:2015
ISO 12312-2:2015(E)
Table 1 — Transmittance requirements for filters for the direct observation of the sun
Maximum luminous transmittance (τ ) 0,003 2 %
v
Minimum luminous transmittance (τ ) 0,000 061 %
v
Maximum solar UVB transmittance (τ ) τ
SUVB v
Maximum solar UVA transmittance (τ ) τ
SUVA v
Maximum solar infrared transmittance (τ ) 3 %
SIR
Uncertainty of measurements of transmittance shall not be greater than 25 % of the measured value.
The measurement of spectral transmittance of filters with high optical density can be best accomplished
with the use of a dual-beam spectrophotometer and comparison beam attenuators. The comparison
beam attenuator should be a physical barrier, such as a perforated mesh, equivalent to a known uniform
level of absorption across the entire waveband of measurement.
4.1.2 Uniformity of luminous transmittance
The relative difference in the luminous transmittance value between any two points of the filter shall
not be greater than 10 % (relative to the higher value). This requirement shall apply within a circle
40 mm in diameter around the boxed centre or to the edge of the filter less the marginal zone 5 mm
wide, whichever is greater.
4.2 Material and surface quality
4.2.1 Requirements
Except in a marginal area 5 mm wide, filters shall be free from defects likely to impair vision in use, such
as bubbles, scratches, inclusions, dull spots, pitting, scouring, pocking, scaling, and undulations. Metal
coated filter materials shall not exhibit more than one pinhole defect not greater than 200 μm in average
diameter within any 5 mm diameter circular zone.
4.2.2 Test method
A filter shall be illuminated from one side by an intense white light source (e.g. projector beam or light
table) and the opposite side viewed through a low power magnifying lens. Metal coated filters showing
visible pinhole defects shall be examined in a light microscope at 25× to 40× magnification.
NOTE A magnifying lens of 4× to 10× magnification can be used.
4.3 Mounting
4.3.1 General
Filters may be made with or without a mounting. If mounted, a filter shall be held securely so that it cannot
be dislodged by normal handling or by gusts of wind. Mountings may be handheld or shaped in the form of
spectacles to be worn on the face in front of any corrective (spectacle or contact) lenses worn by the user.
4.3.2 Dimensions
The filter or filters and mounting assembly shall be of a size sufficient to cover both eyes of the user
simultaneously and in no case shall have overall dimensions less than 115 mm in width and 35 mm in
depth in the plane parallel to the facial plane. Spectacle shaped mountings may have a triangular cut-away
area to accommodate the crest of the nose, not to exceed 15 mm in apical height and 35 mm width at the
base and may have separate filters, one for each eye, provided that the overall dimensions are satisfied.
2 © ISO 2015 – All rights reserved
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SIST EN ISO 12312-2:2015
ISO 12312-2:2015(E)
4.3.3 Material quality
The filter and mounting shall be free from roughness, sharp edges, projections, or other defects which
could cause discomfort or injury during use. No part of the filter or mounting which is in contact with
the wearer shall be made of materials which are known to cause any skin irritation.
5 Labelling
The filter and/or its packaging shall show the following information in the language(s) of the country
where the product is to be offered for sale:
a) name and address of manufacturer of the product;
b) instructions for use in looking at the sun or a solar eclipse;
c) warnings that viewing the sun without an appropriate filter can result in permanent eye injury;
EXAMPLE “Direct viewing of the sun is dangerous if the proper precautions are not taken. Adequate eye
protection specifically designed for viewing the sun is essential and shall be worn so that no direct radiation
from the sun can reach the eye other than that passing through the filter.”
d) warnings that filters that are damaged or separated from their mountings should be discarded;
e) advice on storage, cleaning, and maintenance, as appropriate;
f) obsolescence deadline or period of obsolescence, as appropriate.
© ISO 2015 – All rights reserved 3
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SIST EN ISO 12312-2:2015
ISO 12312-2:2015(E)
Annex A
(informative)
Use of filters for direct observation of the sun
For the direct observation of the sun, only specially designed protective filters should be used. Welding
filters are designed to protect the eyes against ultraviolet, visible, and infrared light whereas the filters
for direct observation of the sun need only to provide protection against visible light. Welding filters
as specified in ISO 16321 with scale numbers 12 to 15 are equally suitable for use with the unaided
eye, however, they should not be used in conjunction with telescopes (in front of the objective) for the
observation of the sun. The selection of the welding filter scale number is a matter of personal preference
in comfort (according to atmospheric conditions and personal glare sensitivity). Filters with category
W12 should be adequate to protect the eyes, but the solar image can be uncomfortably bright. Some
observers might find that the solar image viewed through a W14 filter is too dim. Table A.1 compares the
transmittance properties of welding (W) and solar filters. In the visible spectral range, the transmittance
values are for luminous transmittance as specified in ISO 12311:2013, 7.1.2 and denoted as τ .
v
Table A.1 — Comparison of transmittance properties (%) of solar and welding filters
Filter Category Ultraviolet spectral range Visible spectral range Infrared spectral range
280 nm to 315 nm to Maximum Minimum Maximum 780 nm to
315 nm 380 nm 1 400 nm
Solar for direct τ τ 0,003 2 0,000 061 3
v v
observation
Welding W12 0,000 3 0,001 2 0,003 2 0,001 2 12
Welding W13 0,000 3 0,000 44 0,001 2 0,000 44 8
Welding W14 0,000 16 0,000 16 0,000 44 0,000 16 6
Welding W15 0,000 061 0,000 061 0,000 16 0,000 061 4
NOTE Ultraviolet welding filter transmittances are maximum levels of spectral transmittance measured at
313 nm and 365 nm. Infrared transmittance is mean transmittance in the specified waveband.
Eye protectors for direct observation of the sun should be worn so that no direct radiation from the sun
can reach the eye other than that passing through the filter.
During eclipses of the sun, eye protectors shall be worn whenever a part of the disk of the sun is not
covered by the moon (i.e. during partial eclipse). The only time it is safe to view the sun without an eye
protector is when the moon completely covers the sun in total eclipse.
Retinal safety calculation
Detailed calculations and analysis of retinal hazards from direct viewing of the sun demonstrate that
a thermal injury of the retina is normally not possible unless the pupil is well dilated or unless the
[1][2]
solar disc is viewed through a telescope . The temperature rise in the irradiated retinal image is
insufficient to produce a retinal burn for the unaided eye; even with a 3 mm diameter pupil (which
[1][2][3]
would be quite large for bright daylight) will normally be less than 4 °C .
The sun, instead, poses a photochemical hazard (“blue-light hazard”) not from momentary viewing but
from prolonged staring (as during a partial eclipse) for minutes. The terrestrial radiance of the sun when
7 −2 −1
overhead is approximately 1,3 × 10 W∙m ∙sr and spectral weighting of the solar spectrum with the blue-
5 −2 −1
light-hazard function B(λ) provides effective blue-light radiance values ranging from 4 × 10 W∙m ∙sr to
6 −2 −1
1,8 × 10 W∙m ∙sr , depending upon solar elevation angles greater than 10° above the horizon.
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SIST EN ISO 12312-2:2015
ISO 12312-2:2015(E)
[4]
The maximum staring durations that relate to these blue-light radiances from the ACGIH limits vary
[5]
from only 0,6 s for solar zenith to 2,5 s for the sun at 10° above the horizon (very clear sky conditions)
[6]
. Of course, actual injuries will only occur at greater durations since the exposure limits incorporate a
large safety factor and the limits assume a relatively large pupil size of 3 mm, whereas, the pupil will be
typically 1,5-2 mm under such viewing conditions.
Nevertheless, to provide an example for calculating a required attenuation factor, consider a staring
duration of 1 000 s (~17 min). One would need an attenuation factor of (1 000 s)/(0,6 s) = 1 670, which
would correspond to a neutral filter having a luminous transmittance of 0,06 %. However, practice shows
that one would find it very difficult to stare at the sun with a filter transmitting 0,06 %. Most observers
−2
would find a luminance of ~10 kcd∙m as an upper value of luminance that could be comfortably
[7] 9 −2
viewed. Since the luminance of the overhead sun is 1,6 × 10 cd∙m , a minimum attenuation factor of
160,000 would be required for comfortable viewing (i.e. visual transmittance <0,000 6 % at solar noon.
Hence, the filter transmittances in this part of ISO 12312 are far lower than required to prevent retinal
injury (solar maculopathy). Since the luminance of the solar disc decreases with solar zenith angle, the
comfortable luminous transmittance can be higher than 0,000 44 %. Finally, at sunset, the solar disc is
[2][6]
safe to view on the horizon without protection as the blue light has been scattered out of the image .
© ISO 2015 – All rights reserved 5
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SIST EN ISO 12312-2:2015
ISO 12312-2:2015(E)
Annex B
(informative)
[23]
Solar eclipse eye safety: User’s guide
A solar eclipse is probably the most spectacular astronomical event that many people will experience
in their lives. There is a great deal of interest in watching eclipses and thousands of astronomers
(both amateur and professional) and other eclipse enthusiasts travel around the world to observe and
photograph them.
A solar eclipse offers students a unique opportunity to see a natural phenomenon that illustrates the
basic principles of mathematics and science taught throughout elementary and secondary school. Indeed,
many scientists (including astronomers) have been inspired to study science as a result of seeing a total
solar eclipse. Teachers can use eclipses to show how the laws of motion and the mathematics of orbits can
predict the occurrence of eclipses. The use of pinhole cameras and telescopes or binoculars to observe an
eclipse leads to an understanding of the optics of these devices. The rise and fall of environmental light
levels during an eclipse illustrate the principles of radiometry and photometry while biology classes can
observe the associated behaviour of plants and animals. It is also an opportunity for children of school
age to contribute actively to scientific research — observations of contact timings at different locations
along the eclipse path are useful in refining our knowledge of the orbital motions of the moon and earth
while sketches and photographs of the solar corona can be used to build a three-dimensional picture of
the sun’s extended atmosphere during the eclipse.
Observing the sun, however, can be dangerous if the proper precautions are not taken. The solar
radiation that reaches the surface of earth ranges from ultraviolet (UV) radiation at wavelengths longer
than 290 nm to radio waves in the metre range. The ti
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