e. Blue (Wratten no. 47, also called C5).
This filter has rather
limited usefulness in outdoor photography, but does have uses in copy work
and in separating colors when blue and another color look similarly gray
without a filter.
In landscape photography, this filter is useful for
increasing the intensity of atmospheric haze. Why you might want to do this
is discussed in the next lesson.
The blue filter effectively makes any
emulsion (ortho or pan) act as if it were colorblind. Greens and reds are
rendered as dark grays or blacks. Blues are lightened considerably (Table
Learning Event 6:
USE ULTRAVIOLET (UV), NEUTRAL DENSITY (ND), AND POLARIZING SCREENS
There are some filters that aren't designed exclusively for black and
white film; they work equally well with color, too. The most important of
the lens without affecting its color in any way. If your camera is loaded
with fast film and you find yourself unexpectedly in bright light, you may
not be able to get a good exposure even though you've stopped the lens down
all the way and set the fastest shutter speed. Placing a neutral density
filter in front of the lens is another way of reducing the light reaching
the film to a manageable level. Also, some very effective photos depend on
using very long shutter speeds or very wide lens openings, or even both. A
neutral density filter is often very handy in these situations (Table 2-3).
Ultraviolet filters (also called haze filters) look almost like
ordinary pieces of glass.
They are nearly colorless and require no
adjustment for filter factor.
They serve only to screen out ultraviolet
light without affecting any of the visible colors at all. Their effect is
very subtle. Outdoor scenes, especially those of distant views, often have
a lot of ultraviolet light in them. You can't see it, but you can tell when
it's around because the day will be hazy.