The Cine Technician (1953-1956)

38 CINE TECHNICIAN March 1956 A Technician's Notebook u JOCK" DYMORE'S H.I. CARBONS In his article on High Intensity Carbons in the November issue of the Cine Technician. Mr. Jeakins quoted the American Cinematog rapher and Mr. Howard Cricks in the Kine Weekly as both reporting the development of some new carbons for use in " Brutes " and the 150 amp. type MR-170 lamps, in order to eliminate the 40' ? loss encountered when ordinary white flame H.I. carbons are filtered to obtain a tungsten balance. Readers may be interested to learn that the idea of producing H.I. carbons with a yellow flame, so as to eliminate the necessity of using Y-l gelatine filters, for Technicolor work, was first put forward by a studio electrician, the late Mr. " Jock " Dymore, as far back as 1939. Everyone was aware of the difficulties encountered through the use of the expensive imported Y-l filters, due to rapid fading, buckling and scorching after a few minutes in front of the arc, to say nothing of the element of danger involved in the frequent changing of the hot metal diffuser frames. At Dymore's request Ship Carbon produced a yellow flame carbon designed for use on Technicolor, which would not require the use of Y-l filters and, in fact, Ship produced two carbons. The first one was approximately equal to a standard white flame carbon plus two Y-l's. The other approximated to a white flame plus a single Y-l. On test they appeared to be quite satisfactory, but in view of the rigid attitude of Technicolor in refusing to accept any responsibility for the negative unless it was lit by standard white flame carbons and Y-l filters, the cameraman in question was compelled to reject their use. So they lay in Denham electrical stores until the production of Major Barbara, when the energetic Jock persuaded Ronnie Neame, who lit the film, to try them on black and white. Gradually more and more cameramen were attracted to the use of these carbons, which were " sold " by Jock under the title of " Panchromatic " carbons. The writer in 1946 wrote to six leading cameramen asking them what it was they obtained from the use of the " Pan " carbon on a black and white picture, that they couldn't get with standard white flame carbons mixed with tungsten lighting. In general the replies were that with the Max Factor Pan make-up, artists' faces took on a " nice warm texture " with lighting by this method, and that they would regard the loss of these carbons as a serious handicap to their work. Of course, everybody knows that yellow flame carbons, under the title of " Pan " carbons, were in use as far back as the '20s, for the low intensity 300 and 700mm. arcs. HEAVIER LOAD An interesting thing about these new H.I. " Pan " carbons, which were originally developed for Technicolor and are now widely used on black and white, was that nobody at the time, including the carbon manufacturers, appreciated the fact that this new carbon imposed a much heavier load than the white flame carbon of the same size. Tests carried out by the writer showed that the current consumption of a type 170 lamp using white flame carbons at a line voltage of 115v. passed current of 140-145 amps, whereas the same lamp using the H.I. " Pan " carbon passed a current of 168 amps. Unfortunately, at the latter end of 1945, two things occurred at roughly the same time which aggravated the over-loading problem quite considerably. They were: 1. The introduction of soundproofing by means of asbestos/glass wool linings which were clipped inside the lamp housings. 2. The persistence of a theory that arc lamps in Hollywood burnt much brighter than the same lamps at Denham which led the electrical department into reducing the ballast resistance from .33 ohm to .28 ohm in an attempt to emulate what was reported to us as current Hollywood practice. It will therefore be appreciated that the growing use of these carbons on black and white along with the other factors brought a number of problems, such as pencilling of the negative carbon, instability through inadequate ventilation, and cracked condensers. Manufacturers, not realising the different characteristics of this carbon, supplied negatives admirably suited to burn with 16mm. white flame carbon, but quite inadequately sheathed to cope with the increased current passed by the so-called " Pan " carbon. Denham's problem was solved by restoring the ballast resistance to its correct value and by scrapping the bulky sound proofing. A.C.T. has always been a staunch defender of the British technician. I am sure you will see the importance in an industry so largely dominated by American influence of giving proper credit to the British technicians in this case. A. C. BATCHELOR. The Other Man's Job We print below a letter which we have received from Mr. M. Wynn, of the Camera Section. The suggestion which he puts forward for enabling members of one section to get a deeper insight into the work of their fellow-members in other sections seems to us a first-class idea. >Ir. Wynn writes: " I wonder whether it would be possible for, say, two members of the Camera Section to be invited to see what goes on in the Laboratories, then perhaps a couple of Lab members could be invited to see a production in progress. Exchange visits of this kind would give the other fellow a chance to see what his brother member does towards making a film. They would help towards an appreciation of the difficulties that arise and would, I am sure, lead to a better understanding all round.''