1、STD-ANSI IT2.2b-ENGL 1778 = 072gL50 0558342 917 m- for Photography - Photographic Materials Determination of Safelig iht I ANSUPIMA IT2, :onditions ,26- -1998 This material is reproduced from American National Standard XT 4 2 6 , copyright 1448 , with permission of the American National Standards In
2、stitute, Inc. Not for resale. No part of this publication may be copied or reproduced in any form, electronic retrieval system or otherwise, without the prior written permission of the American National Standards Institute, Inc., 11 West 42nd Street, New York, New York 10036. - -!rra American Nation
3、al Standards Institute 77 West 42nd Street New York, New York 10036 ANSVPIMA lT2.26-1998 Revision and redesignation of ANSI PH2.22-1988 American National Standard for Photography - Photographic Materials - Dete rm in at ion of Safe I ig h t Conditions Secretariat Photographic their existence does no
4、t in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumstances gi
5、ve an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or s
6、ponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard.
7、 Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Published by American National Standards Institute, Inc. 11 West 42nd Street, New York, NY 10036 Copyright O 1998 by American National Standard
8、s Institute All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Printed in the United States of America Contents Page Foreword i Introduction . III 1 Scope . 1 . 2 Normative
9、 references . 1 Maintenance and recording of safelight conditions 3 Evaluation of safelight conditions used during processing . 9 3 Definitions . 1 4 5 Test methods 3 6 7 Evaluation . 10 8 Designation . 11 Fig u res 1 2 3 Partition mask . 7 4 Step mask . 8 Annexes A Safelight testing using halftone
10、images 12 6 Bibliography 14 Typical strip after processing (unsafe condition) . 5 Format of three-partition safelight test 6 I Foreword (This foreword is not part of American National Standard ANSI/PIMA lT2.26-1998.) This standard is based upon an IS0 Committee Draft of the revision of IS0 8374:1986
11、, and it is considered to be a significant improvement over the existing na- tional standard, ANSI PH2.22-1988. Once the work on the revision of IS0 8374 reaches the FDIS stage, Technical Committee IT2 will submit it to ballot for adoption as a joint ANSI/ISO standard. This standard contains two ann
12、exes. Annex A is normative and is considered part of this standard. Annex B is for information only. Suggestions for improvement of this standard will be welcome. They should be sent to the Photographic in such cases, a simple fog test would be adequate. 2 ANSVPIMA lT2.26-1998 4 Maintenance and reco
13、rding of safelight conditions A record shall be made of all pertinent data including the safelight source type (e.g., light-emitting diode, electroluminescent panel, tungsten bulb, sodium vapor lamp, etc.), source wattage or milliamp draw, volt- age, filter used (if any), approximate age of the filt
14、er, type and interior finish (e.g., white, matte black, sil- vered, etc.) of the safelight fixture, distance from the safelight to the sensitized material, exposure times, and processing data. The data for indirect safelight illumination (aimed at walls or ceilings) shall also in- clude the color an
15、d reflectance of the surfaces and appropriate geometrical descriptions. Once established, the safelight exposure variable shall be maintained by ensuring that proper replacement lamps are used, that filters are not fading, that the distance from the safelight to the sensitized material is maintained
16、, and that the environment has not changed (by painting walls, etc.). Any changes to the elements described above shall be evaluated individually via the methods set forth in this standard. 5 Test methods This clause describes two methods of testing to determine the maximum safelight condition. Meth
17、od 1 (see 5.1): The most general and the one that shall be used when the safelightlmaterial relation- ship is unknown. It makes no assumptions regarding: (a) the image density at which the safelight exposure produces the maximum effect; (b) the order of exposures (safelight and image) that produces
18、the maximum effect. Method 2 (see 5.2): Intended for use only when the basic relationship between the safelight and the sen- sitized material is already known. It is thus useful for “in situ“ testing of safelit areas, once Method 1 has yielded the safelightlmaterial relationship. (Method 1 may also
19、be used for “in situ“ testing, but it is more cumbersome than Method 2.) In Method 2, the image exposure is simulated by a uniform exposure that produces the greatest sensitivity to subsequent safelight exposure. (in some cases, the material may be most sensitive over a range of densities from fog u
20、pwards; here, Method 2 can be reduced to a simple fog test.) The description in 5.2 includes testing both orders of exposures (safelight then image, and image then safelight); but if the order producing the greatest safelight sensitivity is known, or if only one order is relevant (e.g., in an area w
21、here photographic materials are manufactured), then the other order may be omitted. Method 2 can be accomplished using a single sheet of sensitized material, as opposed to Method 1 which requires several sheets. 5.1 Method 1 5.1.1 Principle Separate samples are subjected to a series of safelight exp
22、osures before the image exposure and after the image exposure. The maximum safelight exposure that does not affect the image, and also the expo- sure required to produce the smallest detectable change, are determined and used to define the “IS0 maximum safelight condition.“ Alternatively, if one has
23、 already determined whether a given sensitized product shows the first detectable change in the unexposed areas or in the exposed areas at a particular density, the safelight series may be performed on one sample (Method 2, see 5.2). 3 ANSVPIMA lT2.26-1998 5.1.2 Apparatus 5.1.2.1 Step tablet The use
24、 of a transmission step tablet is recommended to create a series of stepped exposures that will provide the range of densities expected in the normal use of the material to be evaluated. For products normally exposed with direct X-rays, the exposure series shall be obtained in a manner appropriate f
25、or radiographic films. For products normally exposed to a halftone pattern, the method described in annex A shall be initially completed in parallel with Method 1. For subsequent testing, the method showing the most sensitivity (the halftone method of annex A or the continuous tone method of the mai
26、n body of this standard) shall be used. If a step tablet is not available, the following procedure may be substituted for the exposure. Cover one end of the piece of sensitized material being tested with a black card or other opaque material and uni- formly flash expose the uncovered area, moving th
27、e card to produce a series of exposure times in seconds such as 1, 2, 4, 8, 16, etc. The spectral quality of the illuminant shall be similar to that normally used for the material. The exposures should produce the full range of densities expected in actual use. A less satisfactory alternative is to
28、give the entire piece of sensitized material, except for a protected border, a uniform exposure through a transparent picture image, providing the picture produces a satisfactory distri- bution of light, medium, and dark tones. It is important to remember that areas receiving lower image exposures a
29、re particularly vulnerable to the effects of low level exposures as might occur under safelight conditions. 5.1.2.2 Opaque cover A black opaque card is needed to limit the area exposed to the safelight illumination. Additional pieces of card and masking tape may be used in the construction of a guid
30、e for positioning the sensitized material and the opaque card in the dark. 5.1.2.3 Timer A means of timing the exposure from the safelight for a few seconds to 8 minutes or longer is required. If a visual timer is used, any light provided by the timer shall be prevented from reaching the sensitized
31、ma- terial unless this light constitutes part of the normal dark room safelight illumination being tested. 5.1.3 Test conditions Samples shall be handled in total darkness except when intended exposures are made. During exposure to determine the strict “IS0 maximum safelight condition,“ the specimen
32、s shall be kept at a temperature of 23C it is important that the exposures produce the full range of densities expected in actual use. Process the strips together in total darkness within 15 minutes to 45 minutes of the last exposure in order to minimize latent image keeping effects. The process sha
33、ll be the same as normally used for the sensi- tized material. 5.1.4.2 Post-exposure test Cut the sensitized material to be tested into several strips, preferably at least 2.5 cm wide. In total darkness, make a step tablet exposure on several strips of the sensitized material. It is important that t
34、he exposures produce the full range of densities normally expected in actual use. Cover one-half of a strip longitudinally with an opaque card. Expose the other half to the safelight illumi- nation for the shortest practical time. Repeat this procedure for each successive strip while doubling the ex
35、posure time. Process the strips together in total darkness within 15 minutes to 45 minutes of the last exposure in order to minimize latent image keeping effects. The process shall be the same as normally used for the sensi- tized material. Densities with side covered Densities with side exposed to
36、safelight Figure 1 - Typical strip after processing (unsafe condition) 5.2 Method 2 5.2.1 Principle Other than the light being tested, all testing shall be performed in total darkness. For the sake of efficiency, three separate tests are typically run on one rectangular sheet of sensitized material
37、that is partitioned into thirds across its width (see figure 2). One third is used for each test. The sample is processed and exam- ined to determine the test and the scale level at which the first detectable change is seen. In the first test, the Uniform Picture Exposure (UPE) precedes the Safeligh
38、t Scale Exposure (SSE) and is called the “Uniform Picture + Safelight Scale” test. In the second test, the SSE is the only exposure given and it is called the ”Safelight Scaleltest. In the third test, the SSE precedes the UPE and is called the ”Safelight Scale + Uniform Pictureltest. 5 ANSVPIMA lT2.
39、26-1998 Test sample Partion Partion Partion 1 2 3 UPE + SSE SS E SSE + UPE Figure 2 - Format of a three-partition safelight test 6 ANSVPIMA lT2.26-1998 5.2.2 Apparatus 5.2.2.1 Partition mask An opaque mask shall be made that occludes two adjacent “partitions“ of the sample as described in 5.2.1 (see
40、 figure 3). This mask shall be used in step #1 of the sequence described in 5.2.4. The same mask, in a different position, shall be used in step #5 of 5.2.4. There should be no need to use this mask with films where the pre, post, or fog exposure tests yield the same “IS0 maximum safelight condition
41、.“ SAMPLE 7 MASK Figure 3 - Partition mask 7 ANSVPIMA lT2.26-1998 _ 5.2.2.2 Step mask An opaque mask or masks shall be made for use in producing the step exposures lengthwise along the L_J_ C_J_ -_A_ -_A_ L_J_ L . I 4 4 -1 A 1 1 /- MASK The goal of this exposure is to expose the test material to yie
42、ld the density at which the material has the greatest safelight sensitivity. The precise value of this density for the photographic material in question can be determined from Method 1. As a guide, it is usually of the order of 0.3 D above Dmin for a negative material or 0.5 D below Dmax for a rever
43、sal material, .e., equivalent to a customer exposure in the toe area of a negative material or the shoulder area of a reversal material. This density shall be uniform over the area of the test material. Such an exposure can be generated by use of a typical enlarger or any other light source that can
44、 provide a uniform illumination over the sample area. When using an enlarger, either use it with no negative material in the gate, or if attenuation is de- sired, insert a piece of neutral density filter. The required uniform density is achieved through trial and er- ror using appropriate sensitomet
45、ric principles and comparing the density of the trial samples with a cali- brated grey scale. As nearly as possible, all layers of a color product should receive an exposure resulting in equal density above Dmin (or below D, in a reversal material) because some just detectable safelight exposures in
46、volve dye development from more than one layer of product. For achieving the desired balance of layer densi- ties, use appropriate sensitometric principles and measure the densities of the trial samples with the ap- propriate geometric and spectral conditions specified in ANSI/ISO 5-2, ANSVNAPM IT2.
47、19; ANSI/ISO 5-3, ANSVNAPM IT2.18; and ANSI/ISO 5-4, ANSVNAPM IT2.17. 8 ANSVPIMA lT2.26-1998 For products normally exposed to a halftone dot pattern (tint pattern) that have been shown to have greater sensitivity to the method described in annex A than to Method 1, a properly exposed halftone dot pa
48、ttern shall be substituted for the UPE. This halftone dot pattern shall be a uniform field of dots having the dot value that shows the greatest sensitivity to safelight exposure (typically 50%) at a screen ruling of 60 lines per cm. The halftone scale shall be exposed in vacuum contact from a hard-d
49、ot tint pattern or by a suitably programmed graphic arts quality image writing device. The method of evaluation shall be as defined in annex A. 5.2.3.2 Safelight scale exposure (SSE) An optimal exposure series for the safelight should be a range of 8 stops to 12 stops, in 1-stop increments. This can be accomplished by the use of a device that sequentially removes the opaque mask(s) from suc- cessive “steps“ of the sample (figure 4). The sample should be at a distance from the safeli
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