1、 The attached SMPTE Engineering Document has been declared “Stable” by the controlling Technology Committee. The SMPTE Operations Manual for Standards states: A document should be stabilized if it is believed to be substantially correct, does not contain harmful or misleading recommendations, may st
2、ill be relevant to equipment or practices in use, is stable, but does not represent current technology, and need not be subject to future reviews. A Stable document shall still be made available and offered for sale by the Society, but it shall be prefaced by a cover page explaining its current stat
3、us. At any time, a Technology Committee may revise, amend, or otherwise initiate a new Project on a Stable document. A Stable document is “In Force”, and not deprecated or withdrawn. * * * * * * * * * * Note: SMPTE “Stable” documents were previously described as “Archived” and the attached document
4、may be marked as “Archived”. The status of a SMPTE document described as “Archived” is exactly as described above for a “Stable” document. Stable documents may not adhere to the latest style and format of SMPTE documents, or to current usage of normative language. Suitable care should be taken in in
5、terpretation. SMPTE STABLE DOCUMENT 1 Scope1.1 This standard specifies the dimensionsrequired for mechanical and optical interchange-ability of lenses for 16-mm and 8-mm motion-picturecameras. For 16-mm cameras with threadedlens mounts, threads having a nominal majordiameter of 1 in are often specif
6、ied. Similarly,for 8-mm motion-picture cameras, threads havinga nominal major diameter of 5/8 in are incommon use.1.2 This standard does not apply to continuous-type motion-picture cameras because of the typeof optical system employed in those cameras.2 Normative referenceThe following standard cont
7、ains provisions which,through reference in this text, constitute provisions ofthis standard. At the time of publication, the editionindicated was valid. All standards are subject torevision, and parties to agreements based on thisstandard are encouraged to investigate the possibilityof applying the
8、most recent edition of the standardindicated below.ANSI/ASME B1.1-1989, Unified Inch Screw Threads(UN and UNR Thread Form)3 Dimensions3.1 The dimensions shall be as specified infigure 1 and table 1.for Motion-Picture Cameras 16- and 8-mmThreaded Lens MountsCAUTION NOTICE: This Standard may be revise
9、d or withdrawn at any time. The procedures of the Standard Developer require that action be taken to reaffirm, revise,or withdraw this standard no later than five years from the date of publication. Purchasers of standards may receive current information on all standards by calling orwriting the Sta
10、ndard Developer. Printed in USA.Revision ofANSI/SMPTE 76-1991ANSI/SMPTE 76-1996SMPTE STANDARDPage 1 of 2 pagesApprovedMay 28, 1996Copyright 1996 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS595 W. Hartsdale Ave., White Plains, NY 10607(914) 761-1100Figure 1 DimensionsD mount C mountDimen
11、sions Inches Millimeters Inches MillimetersW 0.625 15.88 1.000 25.40X 0.115 2.92 0.160 4.06Y 0.484 12.29 0.690 17.53Z 1.000 25.40 1.187 30.15Table 1 SpecificationsREAFFIRMED 20063.2 The lens mounts shall have 32 threads perinch.3.3 The form of the thread shall be in accord-ance with ANSI/ASME B1.1.3
12、4 Limiting dimensions and tolerances of thethreads shall be class NS-2A for the externalthreads on the lens. These dimensions shallinclude plating or any other finish.NOTES1 The values specified for dimension X are the maximumsfor the lenses; additional length for clearance should beprovided in the
13、 camera. With some lenses, the section ofthe mount, smaller in diameter than the root of the thread,extends beyond the limit of dimension X towards theplane of best focus. For such lenses, clearance must beestablished individually.2 For the lens, dimension Y is the distance from theregistering shoul
14、der to the plane of the best overall image.For the camera, dimension Y is the distance from theregistering shoulder to the plane that best represents thelocation of the emulsion on the film in a camera operatingnormally. The allowable tolerance for dimension Y dependsupon the f /number of the lens a
15、nd other variables, and sois not suitable for definite standardization. A tolerance of0.001 in (0.03 mm), applied independently to the lens andcamera, is suggested as a generally accepted practice.3 The values given for dimension Z are maximumdiameters for the seat on the lenses; the seat on thecame
16、ra shall provide clearance for these diameters.Annex A (informative)Additional informationA.1 Past practice has not been entirely consistent so far asdimension X of the D mount is concerned. Some existingcameras will not accept a thread longer than 0.115 in (2.92mm); some lenses have been made with a length of 0.120in or 0.125 in (3.05 mm or 3.18 mm).A.2 If any part of the lens mount has a larger diameter thandimension Z, it should be checked for mechanical interfer-ence with the camera on which it is to be used.ANSI/SMPTE 76-1996Page 2 of 2 pages
