《ISO-1230-2007.pdf》由会员分享,可在线阅读,更多相关《ISO-1230-2007.pdf(12页珍藏版)》请在三一文库上搜索。
1、 Reference number ISO 1230:2007(E) ISO 2007 INTERNATIONAL STANDARD ISO 1230 Third edition 2007-09-01 Photography Determination of flash guide numbers for electronic flash equipment Photographie Dtermination des nombres guides des appareils clairs Copyright International Organization for Standardizat
2、ion Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1230:2007(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance wi
3、th Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing
4、policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Eve
5、ry care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2007 All rights reserved. Unless otherwise specifi
6、ed, 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 either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case
7、 postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/111111100
8、1, User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1230:2007(E) ISO 2007 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodie
9、s (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,
10、 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
11、/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 m
12、ember 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 1230 was prepared by Technical Committee ISO/TC 42, Photography. Thi
13、s third edition cancels and replaces the second edition (ISO 1230:1992), which has been technically revised. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo
14、reproduction or networking permitted without license from IHS -,-,- ISO 1230:2007(E) iv ISO 2007 All rights reserved Introduction In general flash photography, where the flash light source is mounted on a camera, the product of the camera lens -number and the distance from the flash light source to
15、the subject is a constant with respect to the ISO speed of the film or the digital still camera to be used. The illuminance of the subject varies with the distance according to the inverse-square law and, in order to obtain the same suitable exposure on film or image sensor, the -number is adjusted
16、with respect to the square root of the illuminance of the subject. The constant is named “flash guide number” and is a very useful guide for flash photographers, because the guide number represents, in a sense, the power of illumination of the light source, for both flash lamps with and without inte
17、gral reflectors and electronic flash equipment. The camera lens -number setting can easily be calculated by dividing the guide number by the distance from the flash light source to the subject. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=I
18、HS Employees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 1230:2007(E) ISO 2007 All rights reserved 1 Photography Determination of flash guide numbers for electronic flash equipm
19、ent 1 Scope This International Standard specifies the definition and determination of the ISO guide number of electronic flash equipment. It does not specify the definitions and measuring methods for the light output of electronic flash equipment, which are specified in ISO 2827. 2 Terms and definit
20、ions For the purposes of this document, the following terms and definitions apply. 2.1 guide number NGN product of the camera lens -number, required for a suitable exposure on a film or an image sensor, and the distance from the flash light source to the subject with respect to the ISO speed of the
21、film or the digital still camera to be used NOTE The guide number is expressed in metres. Annex A provides the conversion calculation for converting the guide number from metres into feet. 2.2 ISO guide number NISO/GN guide number, for a film or a digital still camera of ISO 100, “X ” synchronizatio
22、n and an exposure time which can fully utilize the total output of the flash light source 3 Calculation of the guide number 3.1 ISO guide number The ISO guide number, NISO/GN, shall be calculated using the following formula: ISO/GN ( )dNk I tt= (1) where k is a constant equal to 0,51 lm 1m2s 1; I(t)
23、dt is the time integral of the luminous intensity of electronic flash equipment, expressed in candella seconds (cds = lmsr 1s). See Annex B for details of Equation (1). Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001,
24、User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1230:2007(E) 2 ISO 2007 All rights reserved 3.2 Guide number for any ISO speed other than 100 The guide number for any ISO speed other than 100 can be calculated from t
25、he following formula: (ISO, ) ISO/GN 100 S S NN= (2) where S is the ISO speed (arithmetic). 4 Designation of guide number Designation of guide numbers on products or instructions should be rounded to two significant digits and followed by metres. When a guide number does not express the ISO guide nu
26、mber i.e. for films or digital still cameras other than those of ISO speed 100 (arithmetic), the reference ISO speed should follow in parentheses. EXAMPLES NISO/GN 20 m NGN 40 m (ISO 400) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Emp
27、loyees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1230:2007(E) ISO 2007 All rights reserved 3 Annex A (informative) Conversion calculation of the ISO guide number from metres into feet A.1 Conversion
28、 factor ISO guide numbers, expressed in feet, can be obtained from the metre guide numbers by multiplying by the factor 3,28. A.2 Designation of guide number in feet Designation of guide numbers on products or instructions should be rounded to the two significant digits and followed by feet. When a
29、guide number does not express the ISO guide number for films or digital still cameras other than ISO speed 100 (arithmetic), the reference ISO speed should follow in parentheses. EXAMPLES NISO/GN 20 m NISO/GN 66 ft NGN 40 m (ISO 400) NGN 130 ft (ISO 400) Copyright International Organization for Stan
30、dardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1230:2007(E) 4 ISO 2007 All rights reserved Annex B (informative) Explanation of g
31、uide number formula B.1 Derivation of the numerical value The numerical value for k = 0,51 in Equation (1) was determined by combining all numerical values and constants in the guide number formula of ISO 1230:1973 as follows: GN 0,3 4 x NCItS= (B.1) where NGN is the guide number, expressed in metre
32、s (m); 0,3 is the metre-foot conversion factor (mft 1); C is a constant and its numerical value is 0,004 5 (lmm 2s 1); It is the effective luminous intensity, I, of the electronic flash equipment, expressed in candelas, multiplied by the effective exposure, t, expressed in seconds (cds); Sx is the a
33、rithmetic ISO film speed of x, and in this case, x is equal to 100. If It is substituted by I(t)dt, Equation (B.1) is equivalent to Equation (1) in 3.1. B.2 Derivation of ISO guide number formula This International Standard was based on the old ANSI PH2.4-1965 (which is now ANSI/NAPM IT2.24-1996) an
34、d the procedure for the derivation of the guide number formula is as follows: The initial equation is based on the calibration equation for incident-light type exposure meters in ANSI PH2.12-1961 as follows: 2 CA t ES = (B.2) where E is the illuminance at the object plane, expressed in footcandles (
35、fc); t is the exposure time, expressed in seconds (s); A is the -number; S is the ASA (arithmetic ISO) film speed; C is a constant and its numerical value equal to 20,8 fcs to distinguish the constant C used in the old ANSI PH2.4-1965, with the constant C in the guide number equation given in Equati
36、on (B.1), C is used here. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1230:2007(E
37、) ISO 2007 All rights reserved 5 According to ANSI PH2.12-1961, the numerical value of K for reflected-light type exposure meters is equal to 1,06 (cdft 2s). From the numerical values of K and C, the diffuse reflectance of the object, which is assumed to be an isotropic diffuser (formerly called a u
38、niform diffuser), can be calculated by the following equation: 1,06 0,160( 16 %) 20,8 = (B.3) The equation for the illuminance with an accessory reflector is: 2 4 M E d = (B.4) where is the luminous flux, expressed in lumens (lm); M is the reflector factor; d is the distance, expressed in feet (ft),
39、 between a lamp and a subject. Combining Equations (B.2) and (B.4) gives: 22 4AdC t MS = (B.5) Rearranging Equation (B.5) gives: 22 4 tMS Ad C = (B.6) GN 4 tMS AdN C = (B.7) By substituting the numerical value of (3,14) and C (20,8), Equation (B.7) becomes: GN(ft) 0,003 8NtMS= (B.8) ANSI then rounde
40、d 0,003 8 (fc 1s 1) to 0,004, which is the numerical value of C in the guide number formula, and corresponds with a reflectance of 16,7%. In the case of electronic flash equipment, the guide number formula is calculated by Equation (B.9) if the relationship I = M/4 is taken into consideration: GN(ft
41、) 0,0044NItS= (B.9) In Equation (B.9), 0,004 is the rounded value of 0,003 8. Since 1 ft = 0,30 m (i.e. 0,304 8 m to be exact), the metre-guide number formula becomes: GN 0,3 0,0044NItS= (B.10) Despite the fact that the calculated value of C is 0,004, the value of 0,004 5 was adopted by TC 42 in the
42、 first edition of this International Standard (ISO 1230:1973) see Equation (B.1) to factor in the discrepancy between the numerical value of the guide number obtained according to the old ANSI PH2.4-1965 and that obtained according to the former German standard DIN 19011 (all parts) 13 14 15 (June 1
43、969 or January 1971 version). Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:31:58 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 1230:20
44、07(E) 6 ISO 2007 All rights reserved Bibliography 1 ISO 6:1993, Photography Black-and-white pictorial still camera negative film/process systems Determination of ISO speed 2 ISO 516:1999, Photography Camera shutters Timing 3 ISO 517:1996, Photography Apertures and related properties pertaining to ph
45、otographic lenses Designations and measurements 4 ISO 2240:2003, Photography Colour reversal camera films Determination of ISO speed 5 ISO 2721:1982, Photography Cameras Automatic controls of exposure 6 ISO 2827:1988, Photography Electronic flash equipment Determination of light output and performan
46、ce 7 ISO 5763:1989, Photography Electronic flash equipment Automatic control of exposure 8 ISO 5800:1987, Photography Colour negative films for still photography Determination of ISO speed 9 ISO 12232:2006, Photography Digital still cameras Determination of exposure index, ISO speed ratings, standar
47、d output sensitivity, and recommended exposure index 10 CIE Publication No.38-1977, Radiometric and photometric characteristics of materials and their measurement 11 ANSI PH2.4-19651), Photography Materials for direct-positive colour print cameras Determination of ISO speed 12 ANSI PH2.12-1961, General-purpose photographic exposure meters (photoelectric type) 13 DIN 19011-1, Photoflash sources Determination of guide numbers and output data 14 DIN 19011-2, Photoflash sources Electronic flash equipment, automatic control of exposure 15 DIN 19011-3, Flashlight so
链接地址:https://www.31doc.com/p-3774416.html