-
It should be known clearly that all
camera filters absorb some light. The important thing is the absorption
of the light is not uniform across the entire spectrum with each filter
absorbing or passing certain portions of light depending on light
source (tungsten or daylight) and color and intensity of the particular
camera filter that is used.
-
Bear in mind that using a camera filter
other than one that is clear or nearly clear will alter the color and
intensity of the specific camera filter being used. Also, remember that
other than for clear or nearly clear filters (skylight and most UV
filters), attaching a filter to a lens will require an exposure
increase. Almost all the modern camera and through-the lens exposure
meters will automatically compensate for light absorption, however, we
still need to take account the exposure decrease caused by camera
filters attached.
-
For example, if you attached a polarizer
to your lens, the subsequent light loss will be about 1.5 f-stops. The
practical effect is very important, a 1.5 f-stop loss translates into
slower shutter speed, larger aperture required or some combination of
the two. In marginal light, the new slower shutter speed might preclude
handheld photography. Whereas when we open the lens aperture to a
larger f-stop, it will diminish depth of field that important detail
would be lost due to image blur.
-
There are several solutions to this
scenario. You can opt for the use of a camera tripod, switch to a
faster film or lower ISO, introduce some form of supplementary
lighting, or split the loss between aperture and shutter speed. The
point to consider is that if you plan to use camera filters at all you
should anticipate their effect on exposure and what that means to the
look of the final image.
|
