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.