The techniques employed for panel balancing are not yet adequate. At present an attempt is made to balance using full size apertures in the projectors. This presents a broad white overlap on the screen making it impossible to evaluate the equality of panel brightness and color. It is also impossible to tell if vignetting along the matchline from any cause is present under this condition. These are strong but incontrovertible statements based upon the facts known to all optical trained persons familiar with photometry. The division line between comparison fields must be as narrow as possible.

    Through the use of an undersize set of masks used in conjunction with a full size set, improvement in technique is possible. These masks can be made by putting tapes at the center of the overlapped area on the screen and cutting the under sized masks to give a butt joint at this position. Viewing should be done through a one inch wide slit cut in a black cardboard held about at arms length so that only the areas immediately adjacent to the butt joint are compared. Under these conditions equality of panes at the matchlines is much more easily compared. The first time this is used, the results will be surprising, particularly if a circular hole the size of a half dollar is used to explore the butt lines from top to bottom.

    To check on projector vignetting of the full sized masks after the lamps are properly adjusted, the full sized masks should be re-inserted and the flat mirrors adjusted again to yield a butt joint. Vignetting if present will be plainly apparent.


[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
[14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25]
HTML transcription ©2002 The American Widescreen Museum