This matter of excess blue in a landscape image goes all the way back to
early B&W photography in the 19th Century when the films and glass plates
would respond only to blue light, hence the always "white" skies in old
photos. The sky was virtually all blue light and would overexpose the
negative in that area. The fact that an image was recorded, and often
extremely well, illustrates how pervasive blue light is in a landscape scene
but not so pervasive that the subjects on the ground were overexposed.
I trick I learned years ago, when using medium format cameras in B&W, came
from the late Ansel Adams. His favorite B&W filter was a no. 12 "Minus
Blue" which filtered out *only* visible blue light to a large degree. This
often was a starting point for determining exposure (he used large view
cameras) and depending upon what you had visualized, you could use an orange
or even a red filter; or you could go the other way using green, light
yellow or even (rarely!) a blue filter. Or none at all.
In the Colorado Rockies, I often used a green filter -- it would still
darken the sky and increase contrast slightly but would lighten the foliage
(of evergreen trees particularly) sufficiently so the trees would not print
black in the final image. Foliage usually has blue light scattered all
through it, particularly at altitude -- I very often was at altitudes
between 10,000 and 14,000 feet. Blue light has the shortest wave length of
all visible light and therefore "scatters" throughout a scene much more
readily than the longer wave lengths at the red end of the spectrum. Wave
lengths shorter than blue start getting into the invisible ultra violet
range and much longer than the red end of the spectrum gets into infra reds,
also invisible to the eye except through special films.
The judicious use (by the photographer's subjective judgement) of filters
carries over into the world of color. I have found a lot of blue in the
Sierra Nevada mountains here in California; in the high desert region east
of those mountains [it may be desert but it's still 6,000 to 8,000 feet
above sea level, hence there's a lot of blue light scattering around]; in
the Rocky Mountains of Colorado and Canada; and in Norway [particularly as
one gets further north -- the light at North Cape, the "top of Europe" can
be very hard to deal with] in the land of the midnight sun.
If you're shooting in early morning or late afternoon light, either
different filtering or no filtering is called for but that depends on the
latitude you're in and the time of year. The San Francisco Bay Area, where
I live, is located at about the same latitude as Gibraltar; Vancouver,
British Columbia, Canada, is located at about at the same latitude as Paris.
I usually do my photography in places such as those mentioned above and have
found that an 81A filter on the camera helps a lot in dealing with a lot of
excessive blue light. Occasionally, I use a stronger 81B but not often. I
feel it's better to deal right at the camera with the light falling on a
landscape before retiring to a darkroom or digital treatment to produce a
print.
The light in Greece was a different story, for the most part, particularly
in landscapes in the Greek Islands. Greece was almost always slightly hazy
for the 7 weeks I was there in '97, so judicious polarizing was called for.
It's a nice trick to clear the haze without introducing a lot of blue tint
where you don't want it. Hawaii is another difficult place for landscape
lighting; Ansel Adams used to say he never did master it. A friend of mine,
who was an assistant to Adams and who lives 4,000 feet up on the side of
Mauna Kea volcano at a place called (naturally) Volcano, Hawaii, has
mastered the light but he has lived there for many years.
Often, in all of these locations and depending upon the subject matter, no
filter at all was called for.
I usually shoot transparencies, not color neg film, and I've been told that
color neg film reacts differently to color filters such as an 81A than
reversal film does. Anyone who uses filtering in any way (color -- reversal
or neg -- or B&W) should do at least some empirical testing to see what
filter causes what changes to one's choice of film and one's choice of
method for creating the final print.
BTW, I made my first photo (B&W) in 1946. Kodachrome was ASA 10 and
Ektachrome didn't exist, to my knowledge.
Hart Corbett
----------
>From: "Frank Paris" <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: RE: filmscanners: orange mask
>Date: Wed, Jan 17, 2001, 9:25 PM
>
> The experience I've had with Provia 100F in the U.S. Pacific Northwest,
> where it is overcast 9 months out of the year, is that it is actually best
> when overcast. If I take pictures of a forested scene that is hundreds of
> feet away (e.g. a waterfalls with surrounding moss-covered cliffs) with a
> blue sky (but no direct sunlight), there is a discouraging blue cast to the
> whole scene. (I can fix most of this in the scanning process.) The colors
> are much more realistic if the same scene is taken with an overcast sky.
> Also, for closeups deep within the forest, even with a blue sky, colors are
> great with no blue overcast. Does anyone have an explanation for this
> behavior?
>
> Frank Paris
