American cinematographer (Jan-Dec 1959)

TECHNICAL QUESTIONS & ANSWERS Conducted by Walter Strenge, A.S.C. Magic "Mylar" This amazing sprocketed splicing tape will repair torn and damaged films, re¬ place torn perforations and allow you to butt-splice without losing a single frame. Comes in transparent for film, opaque for magnetic film. Splice will never come apart and perforations stay permanently repaired with Magic “Mylar." Use Magic "Mylar” for all your film repair and splici 9 jobs. Transparent — For Film 1 6mm. , — Single Perf.... . $5.00 per roll 1 6mm. — -Double Perf. . . 5.00 per roll 35mm. . 9.00 per roll Opaque — ■For Magnetic Fil m 1 6mm. . ..$ 6.60 per roll 35mm. ... 11.00 per roll Write fnr Free Illustrated brochure Florman & Babb INCORPORATED 68 West 45th Street • New York 36, N. Y. UHLER Professional Printers Combination 16mm Continuous... $775.00 f.o.b. Detroit OTHER PROFESSIONAL PRINTERS Reduction & Enlarging 16-8MM.. . $1,295.00 Combination 35MM Continuous. .. $1,445.00 Reduction & Enlarging 35-16MM.. $2,475.00 Cineradiogrophic for 35-1 6MM . $2,275.00 UHLER CINE MACHINE CO. 15762 Wyoming Ave., Detroit 38, Mich. Ph.: UNiversity 1-4663 Cable: “UHLCIMA” Write for further information UESTiONS relating to cinematog^ raphy or other phases of film pro¬ duction are invited from readers and will be answered by letter by Walter Strenge or by other qualified mem¬ bers of the American Society of Cine¬ matographers. Questions and answers "'onsidered of general interest wil' appear in this column. — Ed. QI plan to film a number of stage shows on 16mm film where the ac¬ tion will be continuous for periods of 30 minutes. Can satisfactory picture and sound results be obtained by using one 1200-ft. 16mm camera (single sys¬ tem) for recording the sound track and the master long shot scenes, and a sec¬ ond camera operating in sync with the first to record medium, closeup and angle shots? If so, will it then be pos¬ sible to “raise” the track from the single-system camera negative and ob¬ tain a separate sound track that could be used same as a double-system track, thus making it possible to intercut and edit the No. 1 and No. 2 camera films in the usual double-system manner? Would this result in a satisfactory com¬ posite print? — O. E., Florala, Alabama. Answer: Where you have two nega¬ tives that require intercutting, a sep¬ arate sound negative may be obtained by first making a master positive print from which an optical sound dupe neg¬ ative may be made for double-system printing. This sound dupe negative should give you fairly satisfactory composite sound print quality if the original single-system camera sound negative is of good quality. To obtain the best sound quality when intercutting two single-system negatives, a sound print should first be made from one of the negatives and a re-recorded sound transfer to an opti¬ cal sound negative then made. This can include any necessary sound fre¬ quency and volume correction and should give better sound quality on the final composite print than would be obtained by the optical dupe meth¬ od. — W illiarn Gephart, A.S.C. Associ¬ ate. QI recently purchased a lens on which the footage and f/stop marks were almost entirely obliterated. How can I (1) determine the focal length of this lens, (2) what size area it will cover, and (3) the speed of the lens? — A. M. J., Fresno, Calif. Ansiver: A simple way to determine the focal length of the lens and also its coverage is to mount it in front of a piece of negative film, with ground glass focusing available (as with a camera). Take a picture with the lens, preferably of a building or some other architectural object whose dimensions are known or can be determined. The distance from the nodal point of the lens to the object should also be carefully determined. The focal length can then be computed, containing only the error due to the necessary rack-out. If this rack-out is computed for the focal length indicated and subtracted from the first computed focal length, a fairly accurate focal length will re¬ sult. The coverage, of course, can be de¬ termined from an inspection of the de¬ veloped film. The film area used should be large enough to exceed the coverage of the lens, if extreme coverage of lat¬ ter is desired. The speed of the lens can be most easily determined photometrically by using an ordinary photometer in the image plane and comparing the read¬ ing obtained with those obtained from another lens of the same focal length, under the same conditions. Photo Re¬ search Corp., Los Angeles, and Cam¬ era Equipment Co., Inc., New York City, also can determine fairly ac¬ curately the T-Stop rating of the lens by photometric methods. — If inton Hoch, A.S.C. QI have a Norwood exposure meter and would like to know how to use it to determine exposure where there is backlight in the scene. — C. M., ISeuilly, France. Continued on Page 510 472 AMERICAN CINEAAATOGRAPHER