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February, 1954
HE CINE-TECHNICIAN
23
Foot pedals control forward and reverse film motion Close view of controls and film threading pattern
to test their lenses in a reasonably simple and standardised manner.
A set of six high-contrast and six low-contrast charts is provided with the Circular; the Circular itself is a 27-page book describing very thoroughly the procedure and technique of testing lens resolution, so that comparable results may be obtained by different observers.
The new charts differ from the old in several important respects. Among those noted in the B.J. review are the following:
All the patterns on the new charts use three lines per group; the multiplicity of lines on the original charts made the checking of spurious resolution more difficult.
The ratio of change in size between the patterns has been changed from \/2 to 4v72 to make it easier to distinguish the point at which resolution is lost.
The range of patterns has been changed from 3.5 to 56 lines per mm. on the old chart to 12 to 80 lines per mm. on the new ; experience showing that the latter range was more useful for the type of work likely to be done.
The new charts are supplied in two different contrasts. Black lines on a white ground for the high contrast chart, and grey lines on a
lighter grey ground for the low contrast one.
The low contrast chart has been added, because the performance of a lens on the old type high contrast chart does not necessarily give a true picture of its resolving power when used under normal working conditions.
The review concludes " The Circular is literally a complete text-book tightly packed into 27 pages with 17 figures and 13 tables, and a set each of high and low-contrast charts. This represents just about the best dollar's worth of information ever made available to photographers." The book may be purchased direct from the Superintendent of Documents, U.S. Government Printing Office, Washington 25, D.C., by sending the order, together with the duly filled in Bank's "E Form," through any bank; 334 per cent extra for postage outside U.S.A.
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The arrival of CinemaScope, with its employment of magnetic tracks, has brought to the front the application of magnetic striping to 35mm. film.
We learn from the French firm Pyral that their magnetic striping process is available here through their licensee Zonal Film Facilities Ltd., at The Tower, Hammersmith Broadway, W.6.
Under the chassis view, showing drive system
Rolls or reels of film lie flat