Salt spray pitting and deterioration
generally starts from an edge usually the all important knife edge. This region
is also the most difficult to clean. An oily film at grazing incidences can
contribute color, as well as excessive light loss.
Flare also poses serious problems. It can "flatten" the
contrast of a single panel if a bright object illuminates a single lens. Little
can be done in this case but avoid extreme brightness changes between panels or
avoid including bright objects (as the sun or reflections of it) in or near a
single panel though this is often unavoidable. Not so obvious perhaps is the
necessity of preventing any strong light from falling on the mirrors themselves
even if the source of the light is not included in or near the actual picture.
The scattering of light from dust particles or slight film formation on the
mirrors will contribute strongly to contrast reducing flare, with generally a
fairly strong color contribution. Instances of flare abound in the picture,
often in interior scenes where unshielded lights are placed close to the
camera. Flare can almost never be corrected in printing.
The diaphragm setting problem is obvious, but is complicated
in that two methods are used in making the settings. First in Camera #1, an
extension lever is used and a visual reading is taken from a very finely
calibrated scale. Second, Camera #2 attempts to drive all three diaphragm
controls simultaneously from a single remote control dial, through a complex
mechanical drive, which has for our purposes a fair amount of backlash. When it
is considered that in printing we have found it necessary to divide the usual
printer point interval in half and that about 8 of these half printer points
are equivalent to only one stop on the camera lens, a fair idea of the critical
nature of this adjustment becomes evident.