1、SMPTE 2Y3M 93 W 8357403 0000966 bT3 SMPTE STANDARD for Motion-Picture Equipment - 35- and 70-mm Projection Lenses and Mounts ANSI/SMPTE 243M-1993 Revision of ANSI/ SMPTE 243-1 989 1 Scope 1.1 This standard specifies the lens markings, focal length tolerances, mounting diameters, mechanical factors i
2、n mounting additional lens adaptors to lenses, and the preferred value steps in focal lengths for lenses used in 35- and 70-mm motion-picture projectors . (Focal length referred to in this standard is the equivalent focal length, commonly know as EFL.) 1.2 This standard also specifies the limiting o
3、r maximum available space for projector lens mounts where lenses of varying focal lengths and designs and attachments thereto are used. 2 Marking of prime lenses The focal length of the lens shall be marked on a nondetachable part of the lens barrel in a permament manner in metricvalues on a surface
4、 other than that identified by dimension A. (English units are optional.) 3 Focal length of prime lenses 3.1 The actual focal length shall not differ from the value marked on the lens by more than f 1%. 3.2 Preferred values of focal lengths shall be integral multiples of 5 mm (0.2 in) nominal, over
5、the range 45 mm to 150 mm (1.75 in to 6 in). If English units are also shown, they shall be in decimals. Other values over 150 mm shall be in 1 O-mm steps, and those less than 45 mm can be as is practical for the lens maker. Multicoated lenses shall be so marked or indicated with the abbreviation MC
6、. Lenses made for 70-mm film use shall be so marked in a permanent manner. Page 1 of 3 pages 4 Lens barrel diameter The barrel diameter shall be 70.66 mm (2.782 in) (see dimension A and figure 1) for standard projectors. Some European projectors require lenses of 62.5 mm (2.46 in) which can be provi
7、ded by lens makers at their discretion. Older large lenses have been made at 101.35 mm (3.990 in). It is expected that in most projectors the lens mount will either clamp directly onto the lens barrel or provide a mechanical lens holder which will clamp onto the lens barrel at the specifed diameter.
8、 5 Limiting space dimensions The limiting volume within which the lens, set at infinity, shall mount and perform its function, as in- tended, shall be as specified in table I. These are not necessarily the dimensions of any lens but specify the limits beyond which there may be physical interfer- enc
9、e with the projector mechanism. 6 Optical conversion lenses Anamorphic attachments and other optical converters to be mounted to the objective lens specified or to be mounted in the turret, swing away, or other separate mountings, must fit within the limiting space dimen- sions (see dimension D). 7
10、Lensthread The internal threads for holding attachments, such as anamorphic units, shall be located within dimension A, and shall have dimensions as specified in table 2. CAUTiON NOTICE: This Standard may be revised or withdrawn at any time. The procedures of the Standard Developer require that acti
11、on 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 or writing the Standard Developer. Printed in USA. 595 W. Harlsdak Ave., White Plains, NY 10607 (914)
12、761-1100 Approved March 22,1993 - SMPTE 2431.1 93 8357401 0000767 53T = Standard lenses Millimeters Inches ANSI/SMPTE 243M-1993 Large lenses Millimeters Inches Figure 1 - Lens barrel lomina1 clamping area J K Table 1 - Dimensions 101.6 min 4.00 min 101.6 min 4.00 min 152.4 max 6.00 max 152.4 max 6.0
13、0 max Barrel diameter A t 0.00 t 0.000 70.66 - 0.13 2782 - 0.005 101.35 * 0.13 3.990 1 0.005 Limiting space 6) C D2) P3) Q R S 70.66 max 2.782 max 48.3 max 1.90 max check with projector manufacturer 190.5 min 7.50 min 95.2 min 3.75 min 108.0 rnax 4.25 max 38.1 min 1.50 min 30.5 min 1.20 min 82.6 rna
14、x 3.25 max 48.3 max 1.90 max check with projector manufacturer 190.5 min 7.50 min 95.2 min 3.75 min 108.0 rnax 4.25 rnax 38.1 min 1.50 min 30.5 min 1.20 min Page 2 of 3 pages _. _ - SMPTE 2431 73 m 8357401 O000768 476 m ANSVSMPTE 243M-1993 Table 2 - Standard diameter lenses I Dimensions Millimeters
15、lnches I E Minor diameter 66.80 max F Major diameter 67.77 min G Thread length 5.56 f 0.25 X Thread size 0.706 pitch 2.630 max 2.668 min 0.219 * 0.010 36 tpi Annex A (informative) General information Because of types of glass and tolerances of anti-reflection coatings, lenses can cause a shift in co
16、lor temperature. Using a reliable color temperature meter, the light through the lens as compared to the raw light without the lens should shift less than 400 K. Matched lenses are those which shift the color temperature, one as compared to another, by less than 200 K. (Light readings should be taken with the shutter stopped.) Page 3 of 3 pages
