SMPTE ST 168-2001 Motion-Picture Film (16-mm) Perforated 8-mm Type S (1-4).pdf

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1、1 ScopeThis standard specifies the cutting and perforatingdimensions for 16-mm motion-picture film with 8-mmtype S perforations in positions 1 and 4 and a perfo-ration pitch of either 0.1664 in or 0.1667 in. The widthof the 8-mm strip after processing and slitting is alsospecified.2 Dimensions2.1 Th

2、e dimensions shall be as given in figure 1and table 1.2.2 The dimensions pertain to a safety film asdefined in SMPTE 223M.2.3 Except for dimension A, the dimensionsapply at the time of cutting and perforating forfilm adjusted to a temperature of 23C 1C(nominally converted to 73F 2F) and a rela-tive

3、humidity of (50 2)%. The manufacturermay indicate other nominal humidity conditionsunder which the dimensions apply.for Motion-Picture Film (16-mm) Perforated 8-mm Type S, (1-4)Revision ofANSI/SMPTE 168-1996SMPTE 168-2001SMPTE STANDARDPage 1 of 3 pagesApprovedJune 6, 2001Copyright 2001 by THE SOCIET

4、Y OF MOTION PICTURE AND TELEVISION ENGINEERS595 W. Hartsdale Ave., White Plains, NY 10607(914) 761-1100Figure 1 DimensionsDimensions Inches MillimetersA Film width 0.628 0.001 15.95 0.03A Film width after processing and slitting 0.314 0.002 7.98 0.05B Perforation pitch (long) 0.1667 0.0004 4.234 0.0

5、10B Perforation pitch (short) 0.1664 0.0004 4.227 0.010C Perforation width 0.0360 0.0004 0.914 0.010D Perforation height 0.0450 0.0004 1.143 0.010E Edge to perforation 0.020 0.002 0.51 0.05G Perforation skewness 0.001 max 0.03 maxL 100 consecutive perforation pitches 16.670 0.017 423.42 0.43L 100 co

6、nsecutive perforation pitches 16.640 0.017 422.70 0.43M Lateral perforation displacement 0.552 0.001 14.02 0.03R Radius of perforation fillet 0.005 0.001 0.13 0.03Table 1 SpecificationsREAFFIRMED 20062.4 Some equipment may be used to slit 8-mmtype S film that originally had been designed forthe slit

7、ting of less critical conventional 8-mm filmfrom 16-mm 2R-1500 camera originals or prints.With this procedure, a larger tolerance fordimension A of 0.314 in + 0.002 in 0.003 inmay be used for film that has not been prestripedwith magnetic material. New slitting equipmentshould be designed to functio

8、n within the pre-scribed tolerances.NOTES1 Although film stock with a perforation pitch of 0.1667 in(4.234 mm) may be used as a reversal camera original film,its principal use is for the production of prints. The principaluse of the stock perforated 0.1664 in (4.227 mm) is as anintermediate film in

9、the production of prints. If this film is usedin a camera and slit after processing, the width of the stripsso slit shall be 0.314 in 0.002 in (7.98 mm 0.05 mm).2 The title of this standard was established by the applica-tion of a nomenclature system developed for all film dimen-sion standards. Each

10、 title provides an indication of the filmwidth, a code designation for the perforation shape (BH, KS,DH, or CS), or the number of rows of perforations (1R, 2R,etc.), depending upon which is the significant factor, and theperforation pitch without the decimal point.The numerals (1-4) have been added

11、to the title of thisstandard to specify how the rows of perforations are placedon the film. This designation is necessary only when the filmstock is wider than its end use and more than one combina-tion of perforation rows is possible. The perforation rowsshall be numbered starting at the reference

12、edge. Thereference edge is that edge of the strip nearest to theperforations which is retained on one of the slit prints that isnot discarded in any subsequent slitting. The designation 1through 4 of 16-mm films indicates that the perforations arein row1 adjacent to the reference edge2 on the refere

13、nce side of center3 on the nonreference side of center4 adjacent to the nonreference edgewhen the film end is observed from the base side with thewound roll above and away from the point of observation.There can be two different windings for the same numberedrows of perforations. This applies, howev

14、er, only when thefilm is perforated in the 1-3 position and the designation ofthe film would be 1-3, regardless of winding. Winding couldbe A or B, depending upon the location of the referenceedge (refer to ANSI/SMPTE 75M).Annex A (informative)Additional dataA.1 The dimensions given in this standard

15、 represent thepractice of film manufacturers in that the dimensions andtolerances are for film stock immediately after perforation.The punches and dies themselves are made to tolerancesconsiderably smaller than those given, but since film is aplastic material, the dimensions of the slit and perforat

16、edfilm stock never agree exactly with the dimensions of theslitters, punches, and dies. Film can shrink or swell due toloss or gain in moisture content or can shrink due to loss ofsolvent. These changes invariably result in changes in thedimensions during the life of the film. The change is gener-al

17、ly uniform throughout a roll.A.2 It will be noted that among the various standardsfor slitting and perforating film stock there are often twostandards that seem much alike in wording. The differencelies in the longitudinal pitch which is either 0.1664 in or0.1667 in (4.227 mm or 4.234 mm). In genera

18、l, the longerpitch is for print stock and the shorter pitch is for negativeor intermediate stock.The choice of pitch for negative or intermediate motion-picture film depends, within certain limits, on the type ofprinter to be used. Where release step-printers are used andthe film is stationary when

19、exposed, the choice of pitch isnot strictly limited. Where the film moves continuously overa cylindrical surface at the time of printing (sprocket-typecontact printer), there are three major considerationsinvolved in choosing the pitch. These considerations are:(1) the sprocket diameter and tooth en

20、gagement, (2) the filmthickness, and (3) the film shrinkage and the rate at whichshrinkage occurs.Maximum steadiness and definition are secured on asprocket-type printer when the negative stock is somewhatshorter in pitch than the positive stock in the approximateproportion of the thickness of the f

21、ilm to the radius ofcurvature. For printing on a 72-tooth sprocket (circumfer-ence of about 12 in) with film 0.0055 in to 0.0065 in (0.140mm to 0.165 mm) thick, the optimum pitch differential is0.3%. The use of the ideal pitch differential for the negativewould minimize slippage between the positive

22、 stock andnegative during the printing operation, thus reducing theamount of blurring and jumping of horizontal lines in thepicture or sound image. (This error is to be differentiatedfrom the jump caused by nonuniformity of successivepitches, dimension B.)Experience has shown that the average pitch

23、derived fromdimension L of the intermediate can vary 0.1 % from theideal pitch, which is 0.3% shorter than the positive stock, withoutblurring of picture and sound image being easily detected.SMPTE 168-2001Page 2 of 3 pagesFor many years this desired difference in pitch was causedby the shrinkage of

24、 the negative film during processing andaging. Current film bases shrink less than the earlier onesand hence a shorter initial pitch becomes desirable. Tosatisfy this requirement for picture or sound negatives, it iscommon manufacturing practice to aim for a pitch value of0.2% shorter than the posit

25、ive stock onto which they willbe printed. The additional shrinkage that occurs duringprocessing and the aging that takes place before the releaseprints are made then bring the pitch differential close to theoptimum and desired value of 0.3%. Accordingly, the pitchchosen for the negative or intermedi

26、ate stock is 0.1664 in(4.227 mm).Low-shrinkage negative film perforated to these dimensionsshould not thereafter shrink appreciably more than 0.2%under normal use conditions, and for a reasonable life span,so that the optimum pitch differential from the positive stockof 0.3% 0.1% is maintained. (The

27、 film should be measuredafter equilibration with air at 70F and 55% relative humidityor at the conditions prevailing at the time of perforating.)A.3 The uniformity of pitch, hole size, and margin (dimen-sions B, C, D, and E) is an important variable affectingsteadiness. Variations in these dimension

28、s, from roll to roll,are of little significance compared to variations from oneperforation to the next within any small group of consecutiveperforations. As an example, the uniformity of the margin isuniquely critical for optical printing. During the printing proc-ess, the placement of the image on

29、the film is usually withrespect to successive lateral pairs of perforations at one-frame intervals. During subsequent projection, however, theportion of the image projected is usually located, not bythese perforations, but by the edge of the film. The lateralsteadiness of the projected image is ther

30、efore directlyrelated to the frame-to-frame uniformity of the margin.A.4 The width for 16-mm film is controlled by the shrinkagecharacteristics of the films involved. Thus, there havebeen standards for the width of 16-mm stock of the usualshrinkage and for stock of low-shrinkage characteristics.The

31、purpose was to obtain films of approximately the samewidth regardless of the type of film base during their usefullife. This standard is based on the values adapted to low-shrinkage film base since nearly all films now manufacturedin the U.S. meet the definition noted below.For the purpose of choice

32、 of width, low-shrinkage film baseis film base which, when coated with emulsion and any othernormal coating treatment, perforated, kept in the manufac-turers normal commercial packings for six months at 65Fto 75F, exposed, processed, and stored exposed to air fora period not to exceed 30 days at 65F

33、 to 75F and 50% to60% relative humidity, shall have shrunk not more than 0.2%from its original dimension at the time of perforating.This definition of low-shrinkage film stock has been foundby experience to be useful as a guide to film manufacturersin slitting their stock. Departure from this defini

34、tion shall notbe cause for rejection of the stock. Note that this definitionof shrinkage differs from the criterion applying to the choiceof longitudinal pitch, where greater periods of time areinvolved and where short-time tests can be deceptive.Allowance has been made in arriving at these values f

35、or thecommon tendency of film to expand when exposed to highrelative humidity. Allowance should be made for this factorin equipment design and in no case should the equipmentdesign fail to accommodate a film of 0.630-in width.A.5 The tolerance for the slit width after processing wasestablished to pr

36、ovide the laboratory with the maximumflexibility for the least critical application of commercial8-mm type S prints. For some commercial applications, suchas photographic sound use, it will be necessary for thelaboratory to consider much tighter tolerances. For thesemore critical uses, film shrinkag

37、e characteristics must betaken into account, and the film slit within 0.001 in (0.03mm) variability.Annex B (informative)BibliographyANSI/SMPTE 75M-1994, Motion-Picture Film Raw Stock Designation of A and B Windings SMPTE 223M-2001, Motion-Picture Film Safety FilmANSI/SMPTE 168-1996Page 3 of 3 pages