The Exhibitor (1966)

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A Case Study n Picture Quality KALLET CINEMA, NEW HARTFORD, NEW YORK The Kallet Theatre of New Hartford, New York, was the scene of an experiment in pic¬ ture quality. As the first theatre in the world equipped exclusively with Kollmorgen lenses for every format, it also served for a proving ground for a case study involving screen bright¬ ness and aperture plate dimensions. The in¬ formation gained in this study also reported to the Film Projection Practice Committee of the SMPTE in October of 1966. The exist¬ ence of this experimental data has tended to support the proposed changes and standards which apply to the motion picture theatre in¬ dustry. A condensed version of the report is as follows: The Theatre Description and Geometry: With seating capacity under 1,000 and a nearly square seating area, the theatre fits in the cate¬ gory of typically modern motion-picture the¬ atres. The projection distance from film to screen surface is 144'; the screen maximum is 22^/2' high x 50' wide. The projection angle is 5 degrees downward or less. The Projection Equipment: The screen is a new, flat gain screen, with a gain of less than 1.5. It is installed vertically with black contrast masking on all four sides. The projectors are convertible 35/70mm projectors with standard cast bases and equipped with high intensity carbon arc lamps with 18 inch “cold” mirrors. Shutters were arranged for 50% admission and the light is projected through optical quality port hole windows. The lamps in use, are designed for normal operation between 140 and 160 amps, however, at the first visit I discovered that they were running at the bot¬ tom rectifier tap between 128 and 133 amps. The lamps were not adjusted properly to my way of thinking, and the 70mm picture al¬ though of good quality was remarkably too bright with noticeable flicker in outdoor scenes. Picture Size: On the above mentioned screen, lenses for 1.75, 1.85, and Cinemascope were selected to give exact image height at just over 22'. This resulted in a picture width slightly over 51'. A 70mm lens was installed which provided a picture 22j/2'x50'. In addi¬ tion to the Cinemascope and 70mm pictures, the 1.75 picture at a width of 38%/ and 1.85 picture at a width of nearly 41'. Although the top and bottom masking was adjustable only by hand, the side masking had an electrically operated control to bring it into the 1.75 and 1.85 picture size. Initial Problems: In addition to the lamp problem listed above, which was operating at below its rated amperage, the theatre was originally set up with a supposed 1.85 lens which was actually the wrong focal length giving a picture that was 22' high by nearly 44' wide. It was quite noticeable that their opening picture, which was “Lt. Robin Crusoe, USN,” was noticeably cropped in height be¬ cause the opening titles in initial credits were By G. M. Berggren Manager Theatre Equipment Kollmorgen Corporation simultaneously against the top and bottom masking looking somewhat peculiar. On taking brightness measurements, with a Spectra brightness meter, it was found that the 1.85 picture was approximately 13 foot lamberts in the center, the CinemaScope picture was ap¬ proximately 18, the 70mm picture was between 22 and 26 depending on the carbon setting. Changes to these items are listed below. Aperture Plates: Due to the cooperative na¬ ture of the management, I made certain spe¬ cific requests which they were particularly helpful with. As to aperture plates, I requested that they use machine made unfilled aperture plates cut to the proper dimensions. Tbe 1.85 plate was marked .445 by .825; the 1.75 plate was marked .470 by .825. The CinemaScope plate was marked .715 by .825. The 70mm plate was marked .866 by 1.910. In each of these cases, with a precision vernier caliper, measurements proved that the plates have in fact been cut to .002" within marked amount. Eventually the 1.75 lens and plate were re¬ moved from service, and were not further considered. The wrong focal length lens was eliminated, and SMPTE APAL film was util¬ ized to assure that focal length was correct for the screen, and final adjustments to masking were made and left. These unfiled aperture plates are in use at the present time in this theatre, and I am unaware of any plans to change them or modify them in any way. Of course there is no 1.85 standard, but the di¬ mensions utilized conform to generally ac¬ cepted practice in the industry. The Cinema¬ Scope aperture plate is correct to the standard with the exception that it is .015" undersized on width, which tends to correct its picture size to conform to the 70mm. Of course there is not currently a 70mm standard, however, the dimensions utilized are those normally employed for Todd-Ao, and other 70mm re¬ leases. The aperture plates have been checked to make sure that they are centered left to right and top to bottom in relation to each other, and utilizing the normal lens mount shift between 35 and 70, all pictures fall on the screen in the proper location in height and width. There is approximately a 3" excess of picture on the masking on all sides, which is also the typical aperture plate blur which of course should not be seen on the screen. As a side note, this theatre was installed with accent on picture quality and proper picture size, and no time was spent on aperture plate filing. The concensus of opinion was that the effort was spent in the right direction. For Use of Subjective Test Film: A sample roll of the preliminary SMPTE subjective test film was used at least 10 different times in this particular theatre; for both 35 and Cinema¬ Scope showing, during five visits. The dealer, the manager, the owner, the projectionists, and several other visitors were considerably im¬ pressed by the film, its possibilities, the sound track accompanying the pattern, and there was a general consensus of opinion that it was a particularly rigid test of picture quality. Be¬ cause of lens selection, the showing in Cinema¬ Scope showed the entire measurement pattern with the exception of approximately 7" on the left and right sides. There was a further con¬ sensus of opinion that as remarkable as the test film was with the accompanying sound track, the manager, the owner, and the dealer were unanimous in the fact that it would never be shown to a paying audience; however, the theatre owner indicated his immediate willing¬ ness to purchase a roll of film for use within his circuit. The dealer was similarly interested. Screen Brightness: Following correction of the picture size and possible focus problems, all attention was turned toward screen bright¬ ness control. Tests were taken at various steps on the rectifiers, and on a later trip, lens stops were calculated to even out the change over from one format to another. Eventually, each of the six lens sets were fitted with one type of stop or another, and the lamps were ele¬ vated to 145 amps, which placed them on the middle tap of the rectifier permitting flexi¬ bility in either direction. At this point, the Spectra brightness meter was allowed to op¬ erate continuously for at least half an hour to allow for warm up, and it was carefully zeroed. The correct working distance was remeasured for the lamps, and minor correc¬ tion was made. Next, the positive and negative carbons were adjusted to locate the hot spot by using the meter. After determining this location the illumination was flattened slightly to a proper setting for 1.85. It was further flattened for use with CinemaScope, and the location for 70mm was found. The arc scope was suitably marked and the identical proce¬ dure was performed on the other lamp. The two lamps were again readjusted using the same lens, to assure that they performed within 1 foot lambert of each other. The precom¬ puted stops were installed in the lenses, and focus setting was realigned using the subjective test film. At this particular time the picture size, focus quality, and lamp adjustments were complete. Further correction had been made to control illumination, to compensate for the larger than usual lamps installed. The following is a table of results for this particular theatre averaging the left and right to a single side measurement, and averaging the left and right machine to avoid complexity in reporting. As comment, the lamps had ap¬ parently been installed for proper operation ( Continued on page PE-18) PE-8 PHYSICAL THEATRE • EXTRA PROFITS DEPARTMENT of MOTION PICTURE EXHIBITOR February 15, 1967