Photogenic Professional Lighting PLR500DR - Manual (Page 13)

13
LONG-EXPOSURE EFFECTS
Under low-light conditions, you may have to extend your exposure times to a
point of significant speed loss. With black-and-white films, the effect of this
speed loss is partially offset by wide exposure latitude. Most color films require
more than the normally calculated exposure when the lighting is unusually low.
Also, the sensitivity differences between the many layers of color films can
cause a color-balance shift, which means that you will sometimes need to use
color-compensating filters to achieve an acceptable color balance.
When you must increase the indicated exposure to compensate for long-
exposure effects, use a larger lens opening, if possible. Extending the exposure
time will result in more speed loss, contrast change, and color shift. See the
manufacturers data tables for your specific film to determine what exposure
adjustment and filter may be necessary.
SHORT-EXPOSURE EFFECTS
Extremely short exposures produce essentially the same effect as long
exposures: speed loss. There is also an increased scattering of exposed silver
halide grains, the formation of smaller latent-image centers, and a lower rate of
development at the latent-image centers.
The short-exposure effect appears as lower contrast or reduced density in the
negative. Exposures of 1/10,000 second or shorter can cause this problem.