ISO 516:1999

Photography — Camera shutters — Timing

Defines the characteristics of all types of shutters which are mounted in still cameras and affect the control of exposure, motion-stopping ability and syncrhonization with a photoflash light source. It also specifies the exposure-time markings for the shutters and their tolerances.

Photographie — Obturateurs d'appareils photographiques — Durée d'exposition

Fotografija - Zaklopi na kamerah - Zaklopni časi

Opredeljuje značilnosti vseh vrst zaklopov, ki so nameščeni na kamerah za mirujoče slike in vplivajo na nadzor ekspozicije, zmogljivost ustavljanja gibanja in sinhronizacijo z virom svetlobe za bliskavico. Določa tudi oznake ekspozicijskih časov na zaklopih in njihove tolerance.

General Information

• Status: Withdrawn
• Publication Date: 25-Aug-1999
• Withdrawal Date: 25-Aug-1999
• ICS: 37.040.10 - Photographic equipment. Projectors
• Technical Committee: ISO/TC 42 - Photography
• Drafting Committee: ISO/TC 42/WG 18 - Electronic still picture imaging
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 01-Apr-2019
• Ref Project: SIST ISO 516:2011 - Photography - Camera shutters - Timing

Relations

• Revised: ISO 516:2019 - Camera shutters — Timing — General definition and mechanical shutter measurements
• Effective Date: 12-Mar-2016
• Revises: ISO 516:1986 - Photography — Camera shutters — Timing
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 516
Third edition
1999-08-15
Photography — Camera shutters — Timing
Photographie — Obturateurs d'appareils photographique — Durée
d'exposition
A
Reference number
ISO 516:1999(E)

---------------------- Page: 1 ----------------------
ISO 516:1999(E)
Contents
1 Scope .1
2 Normative reference .1
3 Terms and definitions .1
4 Symbols.4
5 Required characteristics and their tolerances.5
5.1 Exposure time .5
5.1.1 Exposure time marking .5
5.1.2 Tolerances.5
5.2 Delay time.6
5.2.1 Front shutters.6
5.2.2 Focal-plane shutters.7
6 Test methods.8
6.1 General.8
6.2 Apparatus .8
6.2.1 Light source .8
6.2.2 Detector .8
6.2.3 Time-interval meter.8
6.3 Front-shutter test.8
6.3.1 Test assembly .8
6.3.2 Procedure .8
6.4 Focal-plane-shutter test .9
6.4.1 Test assembly .9
©  ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
Printed in Switzerland
ii

---------------------- Page: 2 ----------------------
© ISO
ISO 516:1999(E)
6.4.2 Procedure . 10
7 Explanatory notes. 11
7.1 Tolerance. 11
7.2 Test method . 11
Annex A (normative) Graphic test methods. 13
iii

---------------------- Page: 3 ----------------------
© ISO
ISO 516:1999(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 3.
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.
International Standard ISO 516 was prepared by Technical Committee ISO/TC 42, Photography.
This third edition cancels and replaces the second edition (ISO 516:1986), of which it constitutes a technical
revision.
Annex A forms a normative part of this International Standard.
iv

---------------------- Page: 4 ----------------------
© ISO
ISO 516:1999(E)
Introduction
This International Standard is intended to provide a uniform basis for determining the timing and marking of
exposure times of all types of shutters used in still cameras, and to give suitable definitions of the terms used.
v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD  © ISO ISO 516:1999(E)
Photography — Camera shutters — Timing
1 Scope
This International Standard defines the characteristics of all types of shutters which are mounted in still cameras
and affect the control of exposure, motion-stopping ability and synchronization with a photoflash light source.
It also specifies the exposure-time markings for the shutters and their tolerances.
The tolerances specified are the target values for the shutter performance that can be expected to give good
results. They are not intended for application as a general inspection standard in controlling the performance of
shutters, since tolerances may vary with the feature and price class of camera tested.
Test methods are described for routine manufacturing testing and quality control.
2 Normative reference
The following normative document contains provisions, which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, such publications do
not apply. However, parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent edition of the normative document indicated below. For undated references,
the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of
currently valid International Standards.
ISO 10330:1992, Photography — Synchronizers, ignition circuits and connectors for cameras and photoflash
units — Electrical characteristics and test methods.
3 Terms and definitions
For the purposes of this International Standard the following terms and definitions apply:
NOTE The meanings of symbols used in this clause are given in clause 4.
3.1
front shutter
any shutter in the vicinity of the lens
NOTE 1 The front shutter may be in front of, behind or between the lens elements and may consist of rotating discs, rotating
slats, sliding blades, oscillating blades, etc. Programmed shutters are also included.
NOTE 2 The common characteristic for the front shutter is that the entire picture area is exposed almost simultaneously.
NOTE 3 When the shutter and diaphragm are located too far apart, both exposure and shutter speed may vary at different
points in the picture area.
3.2
focal-plane shutter
any shutter in the vicinity of the focal plane
NOTE 1 The focal-plane shutter may consist of fixed or variable slit curtains, rotating discs, sliding blades, etc.
1

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© ISO
ISO 516:1999(E)
NOTE 2 The essential feature of the focal-plane shutter is that the picture area is exposed incrementally, in such a way that
the time required to expose the entire picture area is greater than the exposure time of any one point.
3.3
effective time
t
e
the best measure of the amount of light falling on the picture area as defined by the following equation
H
t = (1)
e
E
o
NOTE At any point on the picture area, t is generally the same for the entire picture area for front shutters when vignetting
e
is not severe. For focal-plane shutters, t will vary with w and V . Equation (1) may be approximated with the equation (2) for
e c
convenience in measurement:
w
t = (focal-plane shutter) (2)
e
V
c
Equation (2) may only be applied under the condition of w > d /A.
s
3.4
exposure time
t
eo
effective time measured at the centre of the picture area
3.5
total time
t
o
the time for which any given point in the picture area is exposed to light
See Figure 1.
NOTE 1 At any point on the picture area, t is generally the same, or almost, on the entire picture area for front shutters.
o
NOTE 2 For a focal-plane shutter, however, t is dependent on w, A, d and V . The curtain displacement to completely

o s c
expose one point becomes w + d /A, which can be converted to t , if the velocity is known, using the following equation:
s o
d
s
w +
A
t = (3)
o
V
c
NOTE 3 This equation may be inexact in the presence of vignetting.
Figure 1 — Total time for a focal-plane shutter
2

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© ISO
ISO 516:1999(E)
3.6
shutter efficiency
h
ratio of effective time to total time
t
e
h = (4)
t
o
3.7
fluctuation of exposure time
p
the value of p is determined by the following equation
x + s
p
2 = (5)
x-s
Where x and s are the mean and standard deviation of the values of five successive measurements.
3.8
ratio of two adjacent exposure times
q
ratio of the mean values of two adjacent shutter speed settings obtained from values of five successive
measurements, expressed by the following equation:
tn()
q
eo
2 = (6)
tn()+ 1
eo
(n) (n + 1)
NOTE t and t are the exposure times of two adjacent shutter speed settings represented by (n) and (n + 1).
eo eo
3.9
non-uniformity of exposure
r
characteristic which may be found during any single exposure due to lack of coincidence with the principal plane
(front shutter) or to variations in curtain velocity or slit width (focal-plane shutters)
NOTE Such non-uniformity is expressed as the ratio of the maximum and minimum effective time found by exploring the
picture area, and is derived from the following equation:
t max
r
e
2 = (7)
t min
e
3.10
overall time
T
elapsed time for exposure of all points in the entire picture area
NOTE For front shutters, T = t
.
o
3.11
photoflash synchronization delay time
t
d
time interval from the initial closing of the shutter synchronization contacts to the moment at which the shutter
element moves to the specified position (see 5.2)
NOTE For details of ignition circuits of synchronizers, refer to ISO 10330.
3

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© ISO
ISO 516:1999(E)
3.12
X contact
synchronization contact for an electronic flash unit
NOTE The contact closes while the shutter is fully opened to enable reception of the reflected light from the object through
the aperture of the lens or for total illumination of the camera aperture. The X contact may sometimes be used for the M or MF
class of photoflash lamp at the slower shutter speeds.
3.13
M contact
synchronization contact for M class of photoflash lamp
3.14
FP contact
synchronization contact for FP class of photoflash lamp
NOTE This contact is provided only in the focal plane shutter and may be used for M or MF class of photoflash lamp at the
slower shutter speeds.
4 Symbols
= -number of the lens
A f
b = exposure time error
c = tolerance for exposure time
d = tolerance for stop
d = distance between focal plane and curtain
s
E = maximum illuminance (full open shutter)
o
E = exposure value in units
v
e = tolerance for exposure meter
f = tolerance for film sensitivity
H = exposure (time-integral of illuminance)
L = film latitude
m = magnification factor
n = a positive or negative integer or zero
p = fluctuation of exposure time, expressed in E
v
q = ratio of two adjacent exposure times, expressed in E
v
r = non-uniformity of exposure, expressed in E
v
s = width of the mask slit in drum tester
T = overall time in seconds (see Figure 3)
t = minimum contact duration in seconds
c
t = delay time in seconds (see Figures 2 and 3)
d
4

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© ISO
ISO 516:1999(E)
= theoretical exposure time In seconds [see equation(8)]
t
E
t = effective time in seconds (see Figure A.2)
e
t = exposure time in seconds (effective time measured at the centre of the picture area)
eo
t = total time In seconds (see Figure A.2)
o
v = average linear velocity of curtain
c
v = linear velocity of rotating drum periphery
d
w = width of the focal-plane curtain slit
h= shutter efficiency
5 Required characteristics and their tolerances
5.1 Exposure time
Theoretical exposure times that form a series are given, in seconds, by the following equation:
1
t = (8)
E
n
2
Shutters shall be designed to provide exposure times selected from the series below, subject to the tolerances
specified in 5.1.2.
....8,4,2,1,1/2,1/4,1/8,1/16,1/32, 1/64,1/128,1/256, 1/512, 1/1024,1/2048...
NOTE 1 Timing of the shutters should be measured at the appropriate aperture of the lens used (see Figures 4 and 5). In the
case of cameras that have interchangeable lenses, the standard lens should be used for exposure-time measuring.
NOTE 2 In evaluating shutters without lenses, exposure times should be measured under the conditions fixed so as to be
equivalent to the requirements of this International Standard.
NOTE 3 A change in n by one unit requires a change in time by a factor of 2. This unit is called E or a step.
v
5.1.1 Exposure time marking
The exposure-time marking shall be marked as the following rounded-off values of reciprocal numbers of the series
specified in 5.1. Exposure times longer than 1 s shall not, however, be marked as reciprocal numbers, but should
be made evident by color or some other means of identification.
.8,4,2, 1,2,4,8, 15,30, 60, 125, 250, 500,1 000, 2 000.
The highest marking, however, need not necessarily be selected from this series, but the series beginning with the
next lower number should be selected from this series, whenever practicable, and progressing as far as is required
in the particular application.
5.1.2 Tolerances
The tolerances of exposure time error, fluctuation of exposure times, ratio of two adjacent exposure times and non-
uniformity of exposure should be as shown in Table 1 (see also 7.1). The following equation, in seconds, is
applicable to the tolerance of the exposure time:
1
t = (9)
eo
()nb+
2
5

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© ISO
ISO 516:1999(E)
Table 1 — Tolerances for b, p, q and r
Unit: E
v
Quantity
a
b pq r
Exposure
time
1/125 and longer– 0,3 0,3 max. 1 – 0,45 0,2 max.
shorter than 1/125– 0,45 0,45 max 1 – 0,65 0,6 max.
a
The admissible values for individual exposure times are calculated and
tabulated in annex A.
Over the range of - 10 °C to 40 °C, tie tolerances specified in Table 1 should not be exceeded, with the exception of
the tolerance for b which may be exceeded by – 0,25 E over the range of - 10 °C to 0 °C. Furthermore, the
v
relative humidity between - 10 °C and 0 °C should be not more than 50 % and between 0 °C and 40 °C not more
than 80 %.
5.2 Delay time
5.2.1 Front shutters
Delay time and minimum contact duration for synchronization shall be as given in Table 2.
Table 2 — Delay time of front shutter
Minimum
contact
Delay time of the synchronization contact
Type duration
of contact t (ms)
c
t (ms) Remarks
d
a
X— Closing of the contacts shall take place between the moment
(B) at which the shutter admits 80 % of the light admitted at
the maximu
...

SLOVENSKI STANDARD
SIST ISO 516:2011
01-julij-2011
)RWRJUDILMD=DNORSLQDNDPHUDK=DNORSQLþDVL
Photography - Camera shutters - Timing
Photographie - Obturateurs d'appareils photographiques - Durée d'exposition
Ta slovenski standard je istoveten z: ISO 516:1999
ICS:
37.040.10 Fotografska oprema. Photographic equipment.
Projektorji Projectors
SIST ISO 516:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST ISO 516:2011

---------------------- Page: 2 ----------------------

SIST ISO 516:2011
INTERNATIONAL ISO
STANDARD 516
Third edition
1999-08-15
Photography — Camera shutters — Timing
Photographie — Obturateurs d'appareils photographique — Durée
d'exposition
A
Reference number
ISO 516:1999(E)

---------------------- Page: 3 ----------------------

SIST ISO 516:2011
ISO 516:1999(E)
Contents
1 Scope .1
2 Normative reference .1
3 Terms and definitions .1
4 Symbols.4
5 Required characteristics and their tolerances.5
5.1 Exposure time .5
5.1.1 Exposure time marking .5
5.1.2 Tolerances.5
5.2 Delay time.6
5.2.1 Front shutters.6
5.2.2 Focal-plane shutters.7
6 Test methods.8
6.1 General.8
6.2 Apparatus .8
6.2.1 Light source .8
6.2.2 Detector .8
6.2.3 Time-interval meter.8
6.3 Front-shutter test.8
6.3.1 Test assembly .8
6.3.2 Procedure .8
6.4 Focal-plane-shutter test .9
6.4.1 Test assembly .9
©  ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
Printed in Switzerland
ii

---------------------- Page: 4 ----------------------

SIST ISO 516:2011
© ISO
ISO 516:1999(E)
6.4.2 Procedure . 10
7 Explanatory notes. 11
7.1 Tolerance. 11
7.2 Test method . 11
Annex A (normative) Graphic test methods. 13
iii

---------------------- Page: 5 ----------------------

SIST ISO 516:2011
© ISO
ISO 516:1999(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 3.
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.
International Standard ISO 516 was prepared by Technical Committee ISO/TC 42, Photography.
This third edition cancels and replaces the second edition (ISO 516:1986), of which it constitutes a technical
revision.
Annex A forms a normative part of this International Standard.
iv

---------------------- Page: 6 ----------------------

SIST ISO 516:2011
© ISO
ISO 516:1999(E)
Introduction
This International Standard is intended to provide a uniform basis for determining the timing and marking of
exposure times of all types of shutters used in still cameras, and to give suitable definitions of the terms used.
v

---------------------- Page: 7 ----------------------

SIST ISO 516:2011

---------------------- Page: 8 ----------------------

SIST ISO 516:2011
INTERNATIONAL STANDARD  © ISO ISO 516:1999(E)
Photography — Camera shutters — Timing
1 Scope
This International Standard defines the characteristics of all types of shutters which are mounted in still cameras
and affect the control of exposure, motion-stopping ability and synchronization with a photoflash light source.
It also specifies the exposure-time markings for the shutters and their tolerances.
The tolerances specified are the target values for the shutter performance that can be expected to give good
results. They are not intended for application as a general inspection standard in controlling the performance of
shutters, since tolerances may vary with the feature and price class of camera tested.
Test methods are described for routine manufacturing testing and quality control.
2 Normative reference
The following normative document contains provisions, which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, such publications do
not apply. However, parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent edition of the normative document indicated below. For undated references,
the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of
currently valid International Standards.
ISO 10330:1992, Photography — Synchronizers, ignition circuits and connectors for cameras and photoflash
units — Electrical characteristics and test methods.
3 Terms and definitions
For the purposes of this International Standard the following terms and definitions apply:
NOTE The meanings of symbols used in this clause are given in clause 4.
3.1
front shutter
any shutter in the vicinity of the lens
NOTE 1 The front shutter may be in front of, behind or between the lens elements and may consist of rotating discs, rotating
slats, sliding blades, oscillating blades, etc. Programmed shutters are also included.
NOTE 2 The common characteristic for the front shutter is that the entire picture area is exposed almost simultaneously.
NOTE 3 When the shutter and diaphragm are located too far apart, both exposure and shutter speed may vary at different
points in the picture area.
3.2
focal-plane shutter
any shutter in the vicinity of the focal plane
NOTE 1 The focal-plane shutter may consist of fixed or variable slit curtains, rotating discs, sliding blades, etc.
1

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SIST ISO 516:2011
© ISO
ISO 516:1999(E)
NOTE 2 The essential feature of the focal-plane shutter is that the picture area is exposed incrementally, in such a way that
the time required to expose the entire picture area is greater than the exposure time of any one point.
3.3
effective time
t
e
the best measure of the amount of light falling on the picture area as defined by the following equation
H
t = (1)
e
E
o
NOTE At any point on the picture area, t is generally the same for the entire picture area for front shutters when vignetting
e
is not severe. For focal-plane shutters, t will vary with w and V . Equation (1) may be approximated with the equation (2) for
e c
convenience in measurement:
w
t = (focal-plane shutter) (2)
e
V
c
Equation (2) may only be applied under the condition of w > d /A.
s
3.4
exposure time
t
eo
effective time measured at the centre of the picture area
3.5
total time
t
o
the time for which any given point in the picture area is exposed to light
See Figure 1.
NOTE 1 At any point on the picture area, t is generally the same, or almost, on the entire picture area for front shutters.
o
NOTE 2 For a focal-plane shutter, however, t is dependent on w, A, d and V . The curtain displacement to completely

o s c
expose one point becomes w + d /A, which can be converted to t , if the velocity is known, using the following equation:
s o
d
s
w +
A
t = (3)
o
V
c
NOTE 3 This equation may be inexact in the presence of vignetting.
Figure 1 — Total time for a focal-plane shutter
2

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SIST ISO 516:2011
© ISO
ISO 516:1999(E)
3.6
shutter efficiency
h
ratio of effective time to total time
t
e
h = (4)
t
o
3.7
fluctuation of exposure time
p
the value of p is determined by the following equation
x + s
p
2 = (5)
x-s
Where x and s are the mean and standard deviation of the values of five successive measurements.
3.8
ratio of two adjacent exposure times
q
ratio of the mean values of two adjacent shutter speed settings obtained from values of five successive
measurements, expressed by the following equation:
tn()
q
eo
2 = (6)
tn()+ 1
eo
(n) (n + 1)
NOTE t and t are the exposure times of two adjacent shutter speed settings represented by (n) and (n + 1).
eo eo
3.9
non-uniformity of exposure
r
characteristic which may be found during any single exposure due to lack of coincidence with the principal plane
(front shutter) or to variations in curtain velocity or slit width (focal-plane shutters)
NOTE Such non-uniformity is expressed as the ratio of the maximum and minimum effective time found by exploring the
picture area, and is derived from the following equation:
t max
r
e
2 = (7)
t min
e
3.10
overall time
T
elapsed time for exposure of all points in the entire picture area
NOTE For front shutters, T = t
.
o
3.11
photoflash synchronization delay time
t
d
time interval from the initial closing of the shutter synchronization contacts to the moment at which the shutter
element moves to the specified position (see 5.2)
NOTE For details of ignition circuits of synchronizers, refer to ISO 10330.
3

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SIST ISO 516:2011
© ISO
ISO 516:1999(E)
3.12
X contact
synchronization contact for an electronic flash unit
NOTE The contact closes while the shutter is fully opened to enable reception of the reflected light from the object through
the aperture of the lens or for total illumination of the camera aperture. The X contact may sometimes be used for the M or MF
class of photoflash lamp at the slower shutter speeds.
3.13
M contact
synchronization contact for M class of photoflash lamp
3.14
FP contact
synchronization contact for FP class of photoflash lamp
NOTE This contact is provided only in the focal plane shutter and may be used for M or MF class of photoflash lamp at the
slower shutter speeds.
4 Symbols
= -number of the lens
A f
b = exposure time error
c = tolerance for exposure time
d = tolerance for stop
d = distance between focal plane and curtain
s
E = maximum illuminance (full open shutter)
o
E = exposure value in units
v
e = tolerance for exposure meter
f = tolerance for film sensitivity
H = exposure (time-integral of illuminance)
L = film latitude
m = magnification factor
n = a positive or negative integer or zero
p = fluctuation of exposure time, expressed in E
v
q = ratio of two adjacent exposure times, expressed in E
v
r = non-uniformity of exposure, expressed in E
v
s = width of the mask slit in drum tester
T = overall time in seconds (see Figure 3)
t = minimum contact duration in seconds
c
t = delay time in seconds (see Figures 2 and 3)
d
4

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SIST ISO 516:2011
© ISO
ISO 516:1999(E)
= theoretical exposure time In seconds [see equation(8)]
t
E
t = effective time in seconds (see Figure A.2)
e
t = exposure time in seconds (effective time measured at the centre of the picture area)
eo
t = total time In seconds (see Figure A.2)
o
v = average linear velocity of curtain
c
v = linear velocity of rotating drum periphery
d
w = width of the focal-plane curtain slit
h= shutter efficiency
5 Required characteristics and their tolerances
5.1 Exposure time
Theoretical exposure times that form a series are given, in seconds, by the following equation:
1
t = (8)
E
n
2
Shutters shall be designed to provide exposure times selected from the series below, subject to the tolerances
specified in 5.1.2.
....8,4,2,1,1/2,1/4,1/8,1/16,1/32, 1/64,1/128,1/256, 1/512, 1/1024,1/2048...
NOTE 1 Timing of the shutters should be measured at the appropriate aperture of the lens used (see Figures 4 and 5). In the
case of cameras that have interchangeable lenses, the standard lens should be used for exposure-time measuring.
NOTE 2 In evaluating shutters without lenses, exposure times should be measured under the conditions fixed so as to be
equivalent to the requirements of this International Standard.
NOTE 3 A change in n by one unit requires a change in time by a factor of 2. This unit is called E or a step.
v
5.1.1 Exposure time marking
The exposure-time marking shall be marked as the following rounded-off values of reciprocal numbers of the series
specified in 5.1. Exposure times longer than 1 s shall not, however, be marked as reciprocal numbers, but should
be made evident by color or some other means of identification.
.8,4,2, 1,2,4,8, 15,30, 60, 125, 250, 500,1 000, 2 000.
The highest marking, however, need not necessarily be selected from this series, but the series beginning with the
next lower number should be selected from this series, whenever practicable, and progressing as far as is required
in the particular application.
5.1.2 Tolerances
The tolerances of exposure time error, fluctuation of exposure times, ratio of two adjacent exposure times and non-
uniformity of exposure should be as shown in Table 1 (see also 7.1). The following equation, in seconds, is
applicable to the tolerance of the exposure time:
1
t = (9)
eo
()nb+
2
5

---------------------- Page: 13 ----------------------

SIST ISO 516:2011
© ISO
ISO 516:1999(E)
Table 1 — Tolerances for b, p, q and r
Unit: E
v
Quantity
a
b pq r
Exposure
time
1/125 and longer– 0,3 0,3 max. 1 – 0,45 0,2 max.
shorter than 1/125– 0,45 0,45 max 1 – 0,65 0,6 max.
a
The admissible values for individual exposure times are calculated and
tabulated in annex A.
Over the range of - 10 °C to 40 °C, tie tolerances specified in Table 1 should not be exceeded, with the exception of
the tolerance for b which may be exceeded by – 0,25 E over the range of - 10 °C to 0 °C. Furthermore, the
v
relative humidity between - 10 °C and 0 °C should be not more than 50 % and between 0 °C and 40 °C not more
than 80 %.
5.2 Delay tim
...