1、Designation: E 312 06Standard Practice forDescription and Selection of Conditions for PhotographingSpecimens Using Analog (Film) Cameras and Digital StillCameras (DSC)1This standard is issued under the fixed designation E 312; the number immediately following the designation indicates the year ofori
2、ginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONPhotographs are often used to convey information about the ap
3、pearance of objects, materials, orphenomena involved in testing. The appearance of a photograph of an object depends not only on theappearance of the object, but on the conditions of formation of the optical image, the conditions offormation of the photographic record, and the conditions of viewing
4、the photograph. If thephotographic method of recording appearance is to be reproducible from one laboratory to another andif photographs of various specimens or one specimen at various times are to be used for validcomparisons, there must be an established method of describing pertinent conditions,
5、so they may berecorded, communicated, and standardized. The purpose of this practice is to provide such a methodof description.1. Scope1.1 This practice defines terms and symbols and provides asystematic method of describing the arrangement of lights,camera, and subject, the characteristics of the i
6、llumination, thenature of the photographic process, and the viewing system.Conditions for photographing certain common forms of speci-mens are recommended.Although this practice is applicable tophotographic documentation in general, it is intended for use indescribing the photography of specimens in
7、volved in testingand in standardizing such procedures for particular kinds ofspecimens. This practice is applicable to macrophotographybut photomicrography is excluded from the scope of thispractice.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its
8、use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1535 Practice for Specifying Color by the Munsell Sys-temE 284 Terminol
9、ogy of AppearanceE 1360 Practice for Specifying Color by Using the OpticalSociety of America Uniform Color Scales SystemE 1541 Practice for Specifying and Matching Color Usingthe Colorcurve System2.2 ANSI Standards:ANSI/ISO 517-1996, Apertures and Related Properties Per-taining to Photographic Lense
10、sDesignations and Mea-surements3ISO 3664:2000, Viewing ConditionsGraphic Technologyand Photography3ISO 18920:2000, Imaging Materials Processed Photo-graphic Reflection Prints Storage Practices3ISO 6846:1992, Black-and-White Continuous TonePapersDetermination of ISO Speed and Range forPrinting33. Ter
11、minology3.1 DefinitionsAppearance terms used in this practiceconform to definitions in Terminology E 284. Terms related tophotography conform to the cited standards of the AmericanNational Standards Institute.1This practice is under the jurisdiction of ASTM Committee E12 on Color andAppearance and i
12、s the direct responsibility of Subcommittee E12.03 on Geometry.Current edition approved Sept. 1, 2006. Published October 2006. Originallyapproved in 1966. Last previous edition approved in 2002 as E 312 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer
13、Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM Internationa
14、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Significance and Use4.1 This practice provides a basis for choosing, specifying,recording, communicating, and standardizing the conditionsand processes that determine the nature of a photographicimage of a spec
15、imen. Its provisions are particularly usefulwhen the photographic image is used to preserve or commu-nicate the appearance of a specimen involved in an aging orstressing test that affects its appearance. It is often useful tocompare photographs made under identical conditions beforeand after a test
16、to illustrate a change in appearance.4.2 This practice deals with specific details of cameratechnique and the photographic process, so it will probably bebest understood and implemented by a technical photographeror someone trained in photographic science. The personrequiring the photograph must cle
17、arly indicate to the photog-rapher what features of the specimen are of technical interest,so he may use techniques that make those features clearlyevident in the photograph, without misrepresenting the appear-ance of the specimen.4.3 This practice provides useful guidance on presentingphotographs f
18、or viewing, providing an indication of dimen-sions or scale, indicating the orientation of the picture, andreferring to particular points on a picture. These techniquesshould be useful to those writing technical literature involvingillustrations of the appearance of specimens. The methods ofthis pra
19、ctice should contribute materially to the accuracy andprecision of other standards that rely on pictures to indicatevarious grades of some attribute of appearance, such asblistering or cracking.4.4 For acceptance testing, manufacturing control, and regu-latory purposes, it is desirable to employ mea
20、surement, but inthose cases where there are no methods of measuring theattribute of appearance of interest, well-made photographs orphotomechanical reproductions of them may be the bestavailable way to record and communicate to an inspector thenature of the attribute of appearance.5. Descriptors for
21、 Conditions5.1 Primary Points:5.1.1 Central Image Point, IThe geometrical center of thepicture area on the film or plate, designated by the symbol I(see Fig. 1).5.1.2 Nodal Points, H, H8The two points H and H8 in thelens system, located on the line joining the centers of curvatureof the elements and
22、 having the property that any ray from theobject directed toward H emerges from H8 parallel to theoriginal path. The nodal point with respect to rays from theobject is called the “ first nodal point” and is designated by theFIG. 1 Coordinate System for Specifying the Geometric Relationship of Camera
23、, Subject, and LightingE312062symbol H while the nodal point with respect to rays directed tothe image is called the “second nodal point” and is designatedby the symbol H.5.1.3 Central Object Point, OThe point in the objectspace that is imaged at the central image point, designated bythe symbol O. (
24、It is not necessary that any material thing existat this point.)5.2 Primary Axes:5.2.1 Camera AxisThe straight line between the centralimage point and the second nodal point. The distance betweenthese points is called the “axial image distance” and isdesignated by the symbol v.5.2.2 Optical AxisThe
25、straight line joining the centers ofcurvature of the elements of the lens.5.2.3 Field AxisThe straight line between the centralobject point and the first nodal point. The distance betweenthese points is called the “axial object distance” and isdesignated by the symbol u.5.3 Reference Planes:5.3.1 Im
26、age Reference PlaneThe plane normal to thecamera axis, passing through the central image point.5.3.2 Lens Reference PlaneThe plane normal to the fieldaxis, passing through the first nodal point.5.3.3 Object Reference PlaneThe plane normal to thefield axis, passing through the central object point.5.
27、4 Orientations:5.4.1 Film OrientationThe film or detector orientation isdescribed in a right-handed orthogonal coordinate systemhaving x8 and y8 axes in the image reference plane and z8 axison the camera axis, with the positive direction away from thelens. A film plane is described by the angles of
28、a directionvector making an angle g with the z8 axis and having aprojection on the image reference plane making an angle h withthe x8 axis.5.4.2 Lens OrientationThe lens orientation is described ina right-handed orthogonal coordinate system having xLand yLaxes in the lens reference plane and zLaxis
29、on the field axis,with the positive direction toward the object space. The xLaxisis parallel to the x8 axis and the yLaxis is parallel to the y8 axis.The lens orientation is described by the angles of a directionvector making an angle k with the zLaxis and having aprojection on the lens reference pl
30、ane making an angle l withthe xLaxis.5.4.3 Object OrientationThe object orientation is de-scribed in a right-handed orthogonal coordinate system havingx and y axes in the object reference plane and z axis on the fieldaxis, with the positive direction toward the lens. The x axis isparallel to the x8
31、axis and the y axis is parallel to the y8 axis.Anobject plane can be described in terms of the angles of adirection vector making an angle i with the z axis and havinga projection on the object reference plane making an angle jwith the x axis. Since an object plane may or may not passthrough the cen
32、tral object point, the intersection of the planewith the z axis must be stated. If a cylindrical coordinate isfound useful, the distance from a point to the z axis measuredalong the normal to the z axis may be designated by the symbolp. If there are a number of planes or points to be specified, they
33、can be numbered and the coordinates given numerical sub-scripts accordingly, for example, x1,x2,x3,i1,i2,p1,p2, etc.5.4.4 Illuminant OrientationThe geometrical aspect ofthe illumination is described with respect to the same coordi-nate system used for describing the orientation of the object.The cen
34、ter or centroid of a light source is designated by thesymbol L, with the appropriate subscript when more than onelight source is used. The distance between the central objectpoint and the center of a light source is designated by thesymbol r, with the appropriate numerical subscript. The direc-tion
35、of the light from the point O is described in terms of theangles of a direction vector making an angle a with the z axisand having a projection on the object reference plane makingan angle b with the x axis, or, alternatively, making an angle cwith the yz plane (the angle c being positive on the pos
36、itive xside) and an angle e with the xz plane (the angle e beingpositive on the positive y side). The diameter of the lampreflector is designated by the symbol d, with appropriatesubscript. The coordinates (x, y) of the point on the objectreference plane toward which the lamp reflector is directedmu
37、st be given. The size and shape of the lamp and reflectormust be described with sufficient precision for the intendedpurpose.5.5 Spectral Nature of Illumination Incandescent lampsmay be specified adequately by stating the kind of illuminant,the rated color temperature, and the electrical potential,
38、involts, at which the lamps are operated. The correlated colortemperature of these lamps increases about 11 K for each voltincrease in applied potential, in the neighborhood of 115 V. Aslamps are used, the correlated color temperature (at a givenvoltage) decreases, often from 50 K above to 50 K belo
39、w therated value during the life of the lamp. Fluorescent lamps, arcs,and flash lamps differ more than incandescent lamps fromblack-body spectral emittance and must be described in detailas to make, model, type, etc. The nature of reflectors, includingincidental nearby surfaces, can have an importan
40、t effect on thespectral nature of the energy falling on the object. Theneutrality of such surfaces should be specified when spectralquality is of interest.5.6 Contrast:5.6.1 Object-Surround ContrastThe appearance of an ob-ject may depend on the contrast between the object and thebackground or other
41、visual surroundings against which theobject is seen. The orientation of the background or surround-ing materials may be described in the same way as theorientation of the object and the reflection characteristics of thematerials appearing with the object may be completely speci-fied. However, it is
42、usually more convenient to specify the ratioof the luminance of the object to the luminance of thebackground or other surroundings, as measured from thedirection of the camera lens by a photographic exposure meter.If constant contrast is desirable, it may be specified in that waybut it should be not
43、ed that the use of constant contrast tends tominimize the visual appreciation of the variation of lightnessamong specimens.E3120635.6.1.1 If the object-surround contrast is specified for somestandard object, it will vary from one specimen to another,according to the lightness of the specimen. A matt
44、e, neutral-gray card of specified reflectance may serve as the standardobject. Such a neutral test card with a diffuse reflectance of18 % on one side and 90 % on the other is sold by dealers inphotographic supplies.4The placement of the test card in theobject space must be specified.5.6.2 Illuminati
45、on ContrastThe appearance of an objectmay depend on the ratio of illuminances produced at the objectby the various sources of illumination. This effect is mostnoticeable when surface texture is of interest. The ratios maybe conveniently specified by the ratio of luminances producedby the sources sep
46、arately on a matte, neutral-gray test card inthe object space. The ratio of luminances can be measured witha photographic exposure meter. The exact value of the reflec-tance of the test card is immaterial for the purpose, as long asthe card reflects enough light for accurate measurement.However, the
47、 surface must reflect diffusely. The placement ofthe test card in the object space and the point at which themeasurement is made must be specified. Normally the cardwould be placed in the object reference plane and the mea-surement would be made at the point O.5.7 PolarizationUnwanted specular refle
48、ctions from theobject are often avoided by the use of polarizers between thelamps and the object and a polarizing filter placed over thecamera lens, or both. Since the use of such polarizers may havea pronounced effect on the appearance of an object as depicted,polarizers should be used in specimen
49、photography only whenrequired to depict the object most effectively, and in every casethe usage should be clearly specified.5.8 Focal Length of LensOne of the principal character-istics of a photographic lens is its focal length (equivalent focallength), which is the distance measured along the optical axisfrom the second nodal point to the plane of best averagedefinition when the camera axis, optical axis, and field axis arecollinear and the axial object distance is more than 1000 timesthe axial image distance. The symbol for focal length is f. (See7.3 for a
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