ISO 10330:1992

INTERNATIONAL
IS0
STANDARD
10330
First edition
1992-I l-l 5
Photography - Synchronizers, ignition
circuits and connectors for cameras and
photoflash units - Electrical
characteristics and test methods
Photographie - In terrup teurs synchronis&, circuits d ‘amorCage et
connecteurs pour appareils de prise de vue et sources d’klairs -
Caractkristiques 4ectriques et mbthodes d’essai
Reference number
IS0 10330:1992(E)

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IS0 10330:1992(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(I EC) on all matters of electrotechnical standardization.
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 castina
”
a vote.
International Standard IS0 10330 was prepared by Technica Committee
lSO/TC 42, Photography.
Annex Af orms an integral part of this International Standard Annexes B
and C are for in formation 0 nly.
0 IS0 1992
All rights reserved. No part of this publication may be reproduced or utilized in any form or
by any means, electronrc or mechanical, including photocopying and microfilm, without per-
mission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii

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IS0 10330:1992(E)
Introduction
When a camera is used in conjunction with a photoflash unit, the photo-
flash unit can fail to fire, depending upon the combination. The possible
causes include a failure of the camera or photoflash unit, poor electrical
contact at the connection between both, and the signal transferred to the
photoflash unit for firing it being improper.
Malfunctioning of the synchronization switch in the camera can cause the
photoflash unit to be not fired. When a photoflash unit having an ignition
circuit of high-voltage and/or high-current type (see B.l) is used with a
camera, operating the shutter can produce a spark discharge across the
synchronization contacts, resulting in the metallic surfaces of the contacts
being deteriorated. With the synchronizer having such a fault, the contact
resistance of the contacts is increased, therefore, when a photoflash unit
with an ignition circuit of low-voltage and/or low-current type is operated
with the synchronizer having such a contact fault, it can fail to fire.
When more than one photoflash unit is connected in parallel and the ig-
nition circuit terminal voltage and polarity for one photoflash unit differ
from those for the other(s), the different voltages and polarities can inter-
fere with each other, resulting in a part of the units failing to fire or being
damaged. When more than one photoflash unit having an ignition circuit
of high-voltage and/or high-current type is connected in parallel, the
synchronizer contacts in the camera can become welded, with the result
that the synchronizer loses its function as the switch.
With some photoflash units having an ignition circuit of high-voltage
and/or high-current type, releasing the camera shutter permits a current
as high as several tens of amperes to flow through the synchronization
contacts, and depending upon the construction of the camera synchronizer
terminals and the handling of the photoflash unit, the operator can be
subjected to electrical shock.
To avoid these problems, this International Standard defines the charac-
teristics of the camera synchronizer and photoflash unit.
For information concerning the safety of ignition circuits for use with
photoflash units, refer to IEC 491.
. . .
III

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INTERNATIONAL STANDARD IS0 10330:1992(E)
- Synchronizers, ignition circuits and
Photography
connectors for cameras and photoflash units -
Electrical characteristics and test methods
1 Scope 3 Definitions
This International Standard specifies the electrical re- For the purposes of this International Standard, the
quirements of the camera synchronizer, the ignition following definitions apply.
circuit in the photoflash unit and the cable to connect
these and the test methods to secure positive firing
3.1 synchronizer: Provided in a camera or shutter
of the photoflash unit.
unit to fire the photoflash unit in synchronization with
the operation of the camera shutter, it consists of
synchronizer terminals, a synchronization switch and
a circuit which connects these.
2 Normative references NOTE 1
For details of synchronization, refer to IS0 516.
The following standards contain provisions which,
3.2 synchronizer terminals: Part of
the
through reference in this text, constitute provisions
synchronizer, these couple the camera or shutter unit
of this International Standard. At the time of publi-
with the photoflash unit. The same as the accessory
cation, the editions indicated were valid. All standards
shoe with electrical contacts that is defined in
are subject to revision, and parties to agreements
IS0 518 and the socket defined in IS0 519.
based on this International Standard are encouraged
to investigate the possibility of applying the most re-
3.3 ignition circuit terminals: Part of the photo-
cent editions of the standards indicated below.
flash unit, these are connected to the synchronizer
Members of IEC and IS0 maintain registers of cur-
terminals to couple the camera or shutter unit with
rently valid International Standards.
the photoflash unit for permitting firing operation, The
same as the foot with electrical contacts that is de-
IS0 516:1986, Photography - Camera shutters -
fined in IS0 518, the plug defined in IS0 519 and the
Timing.
sockets defined in IS0 8581.
IS0 518:1977, Photography - Camera accessory
3.4 synchronization switch: Switch provided for
shoes, with and without electrical contacts, for
firing the photoflash unit. It may be a mechanical or
photoflash lamps and electronic photoflash units.
electronic switch.
IS0 519:1974, Photography - Small flash con-
3.5 synchronizer leakage current: Current flowing
nections for hand-held cameras - Dimensions.
through the synchronizer when the specified voltage
IS0 8581: -‘1, Photography - Electronic flash equip- is applied across the synchronizer terminals with the
synchronization switch turned off.
ment - Connectors to synchro-cord.
I) To be published.
1

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IS0 10330:1992(E)
3.6 dynamic characteristics of synchronizer: Vari- camera in parallel by use of a device such as an
ation with time of the voltage appearing across the adapter, it is recommended that a reverse current
prevention circuit be incorporated in the adapter or the
synchronizer terminals when the camera synchronizer
respective photoflash units to avoid an electrical in-
is operated.
terference of one photoflash unit with another.
3.7 ignition circuit: Part of the photoflash unit pro-
vided to receive the signal from the synchronizer and
fire the electronic flash tube or flash bulb. 4.1.1 For the “camera accessory shoe with electrical
contacts” and the “foot of photoflash equipment with
electrical contacts” defined in IS0 518, the contact P
4 Requirements
shown in figure 1 shall be the positive pole, while the
surface 0 shall be the negative pole and when the
4.1 Polarities for synchronizer terminals and
photoflash unit is connected to the camera, the po-
ignition circuit terminals
tential for P shall be higher than that for 0.
The polarity of the synchronizer terminals in a camera
4.1.2 For the “socket and plug in small flash con-
and that of the ignition circuit terminals in a photoflash
nections for hand-held cameras” defined in IS0 519,
unit coupled with the camera are defined in 4.1 .I and
4.12. The polarity of the camera synchronizer ter- the part P shown in figure 2 shall be the positive pole,
minals must be matched to that of the ignition circuit while the part Q shall be the negative pole and when
terminals in the coupled photoflash unit. When more the camera is connected to the photoflash unit, the
potential for P shall be higher than that for 0.
than one photoflash unit is connected to a single
Q
- Insulation
l---- Insulation
Foot
Shoe
Figure 1 - Polarities for camera accessory shoe with electrical contacts and foot of photoflash equipment
with electrical contacts
-4nsuLat ion
Insulation
Plug
Socket
Figure 2 - Polarities of socket and plug in small flash connection for hand-held cameras

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IS0 10330:1992(E)
4.2 Voltage across and current through 4.4 Dynamic characteristics of synchronizer
synchronizer terminals and ignition circuit
When the camera is operated with a 24 V d.c. power
terminals
supply and 240 a resistor connected across the cam-
The voltage applied across the camera synchronizer era synchronizer terminals in series (see figure6) and
terminals and that developed across the ignition cir- the synchronizer has an electronic switch, then the
cuit terminals in the photoflash unit shall not exceed terminal voltage for the synchronizer shall be main-
tained at I,5 V or less until the synchronization switch
24 V dc.
is turned off (see the continuous thick line in
NOTE 2 The 24 V d.c. value is the same as the value of figure 4).
the “safety extra low voltage” specified in 8.1 in
I EC 335-l : I 976. On the other hand, when the synchronizer has a
mechanical switch, at least one of the time periods
The synchronization current flowing through the cam- (7’, to Tn) between the moment the synchronizer ter-
era synchronizer terminals shall be 100 mA at maxi- minal voltage reaches 21 V and the moment a time
of 150 ps elapses and during which the voltage across
mum and the current flowing through the ignition
the synchronizer terminals is maintained at a value of
circuit terminals in any one of the photoflash units
shall be 30 mA max. I,5 V or less, shall be 10 ps or more (see the broken
line in figure4).
NOTES
4.3 Ignition circuit operation
5 When the synchronizer has a mechanical synchron-
ization switch, it is desirable that after a time of 150 ps
When a 4,4 Ma resistor is connected across the ig-
elapses, the synchronizer terminal voltage be maintained at
nition circuit terminals and a pulse voltage as shown
1,5 V or less over as long a time period as possible.
in figure3 is applied across the terminals, the photo-
flash unit shall be fired. 6 It is desirable that the synchronization switch be opened
after th e shutter closing operation is started.
NOTES
3 The resistance value of 4,4 Ma is specified in consider-
4.5 Synchronizer leakage current
ation of the synchronizer leakage current and the cable in-
sulation resistance.
When a 24 V d.c. voltage is applied across the camera
4 See A.2 for the requirements for a photoflash unit having
synchronizer terminals with the camera synchron-
an ignition circuit which is equipped with precautions
ization switch turned off, the leakage current shall be
against accidental firing and failure to fire due to noise or
5 PA or less.
chattering of the synchronization contacts.
4.6 Electrical characteristics of cable
4.6.1 Cable resistance
VF
When the cable is short-circuited at one end, the re-
sistance across the terminals at the other end shall
be 2 a or less.
vss
NOTE 7 When an extremely long or special cable is used,
it should be checked for inductance and capacitance.
10 ps 4.6.2 Cable capacitance
1 ps max.
t/ 4
The cable shall have a capacitance of 3 000 pF or less.
VF : Voltage developed across ignition circuit terminals
in photoflash unit (24 V d.c. max.)
Vss: I,6 V
4.6.3 Cable insulation resistance
Voltage waveform The insulation resistance of the cable shall be 50 Ma
Figure 3 across ignition
circuit terminals or higher at 100 V dc.

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IS0 10330:1992(E)
I
VC
I/
VT A-----
l
f
I
I
I
I
f
I
I
I
1
I
I
Shutter closing
operation is started
Vc: Testing voltage, 24 V
VT: Defined synchronizer starting voltage, 21 V
Vs: Upper Limit of defined synchronizer on-state voltage, I,5 V
Dynamic characteristics of synchronizer
Figure 4 -

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IS’0 10330:1992(E)
sistance value for the variable resistor (Rv) and the
5 Test methods
input impedance across the measuring terminals in
the oscilloscope connected in parallel with the variable
5.1 Ignition circuit operation
resistor is 4,4 MQ.
Connect a pulse generator, a variable-voltage type d.c.
voltage generator, a transistor switch, an oscilloscope Drive the pulse generator PG with the waveform
...