American cinematographer. (1939)

.Reeves Builds 16^35mnu Developer WITH the increasing use of 16mm. film, both in the form of reduction prints, dupe negatives and prints, and direct 16mm. negative and prints, many commercial and private laboratories are being confronted with the technical problems of handling both standard and sub-standard film with a minimum of equipment. In large plants, these problems are minimized, since separate units, espe¬ cially devoloping machines, can be de¬ voted to each class of work. But in a majority of the plants doing such work, conditions seldom permit such a prac¬ tice. It is highly desirable that such equipment be able to process both 35mm. and 16mm. film, and if possible both negative and positive, interchange¬ ably. But several mechanical problems make this difficult. Recent modifications in the design of the well known Art Reeves automatic developing machine are held to elimi¬ nate these difficulties, and to permit the machine to be used interchangeably for processing all types of film. One of the outstanding practical problems has been simplifying the op¬ eration of rethreading the machine when changing from 35mm. to 16mm. film. In most conventional designs, this must be done by hand, involving both trouble and loss of time. The rollers which carry the film through the machine are of recessed construction, with the standard film carried on the outer edges, and 16mm. riding within the recessed portion. Due to this construction the 16mm. film, moving on what are in effect smaller rollers, travels at a lower speed than the 35mm. film. Compensated Take-Up Once the machine is completely threaded with film of either size, this differential is of no consequence: but when 16mm. is connected to a strand of 35mm. already in the machine, and the latter is used to pull the smaller film through the unit, a serious problem arises. The take-up, which is proportioned to the travel of the larger film through the machine, tends to pull the strand through faster than the smaller rollersegments can feed the 16mm. film through. The result is usually enough tension to snap the strand. In the Reeves machine this is now compensated by an additional fi'm-loop between the dry-box and the take-up reel. This passes through a driving roller which is so interconnected with the drive and take-up reel that the take-up can only revolve at a speed coordinated with the lower peripheral speed of the rollers when threaded with 16mm. film. Thus the take-up tension remains normal at all times. With this refine¬ ment, it is not only possible to use the Plan of Art Reeves inter-changeable 16mm.-35mm. developing machine. Dotted line at takn-off end indicates path through compensating roller. length of 35mm. film or leader in the machine to rethread it with 16mm. leader, but to clip a roll of 16mm. film to the end of a length of 35mm. film being processed, and to develop 16mm. and 35mm. consecutively, with no more delay than occurs in clipping a fresh roll of standard film to the end of the strand. Wide Range of Developing-Times The fact that 16mm. negative, for the best results, usually requires processing in solutions of greater fine-grain char¬ acteristics than those ordinarily used for 35mm. negative raises another problem. These ultra fine-grain develop¬ ers almost always require a con¬ siderably longer developing time, often double that normally used for 35mm. negative. In the Reeves machine this type of specialized treatment is made more feasible by the use of an infinitely variable speed control. This consists of a special transmission-unit between the driving motor and the machine. It per¬ mits variation of developing time be¬ tween two and 20 minutes. The machine is further instantly inter¬ changeable between positive and nega¬ tive processing. Separate tanks are provided for the positive and negative solutions. Both of these sections are normally kept threaded at all times. In the section not in use, the film leader is simply disconnected from the strand, and allowed to hang loosely in the tank, with the two ends held in (Continued on Page 566) December, 1939 • American Cinematographer 541