I suspect that there is a considerable distortion of the
available light's color balance at the forest floor where
little if any direct sunlight may be visible.
The usual B&W films are color balanced for tungsten but
wonder if a light yellow filter filter goes far enough towards
muting the preponderant available blue. Would an orange
filter be more correct? Also, yellow or orange, would
filter factors need to be increased in such a blue
blue-green environment? Dan
As I run what you are saying in my head, I'll think it through by just speaking it.
The color temperature in the forest shadows will be bluer. Shadows illuminated by sky alone will be bluer, therefore, any blue absorbing filter such as the yellows, orange, or reds will serve to reduce the shadows to even lower values by decreased negative density and thus darker print value. To compensate you would have to increase the exposure, but then be concsious of where your highlights are on the scale. I think, if I understand you correctly, that an increase in exposure to support the shadows is needed, not an increase in the filter factor. IMO, the factor should remain the same, but I'm not completely experienced in the use of filters, so I'm out on a limb here, IDK. Someone is bound to correct me, which is good.
Chuck
__________________
"Photography is an illusion. It is amazing that human beings consider a photograph to be a representation of reality."
---John Sexton
I should have said...shadows illuminated by blue sky alone, will be bluer.
An overcast day, of course, will have much less blue.
__________________
"Photography is an illusion. It is amazing that human beings consider a photograph to be a representation of reality."
---John Sexton
Under the forest canopy there is no preponderance of blue light. To have blue shadows you need them filled in by the blue of the sky...under the forest canopy you can barely see the blue sky, therefore it cannot be filling in the shadows. The light is scattered and reflected from a preponderance of green/brown surfaces.
At least that's the way it is here in a temperate rainforest from my vantage point on the forest floor. Near the top of the canopy the shadows would probably get bluer, but its hard to set up my 4x5 over a hundred feet from the deck
Murray
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Note to self: Turn your negatives into positives.
Last edited by MurrayMinchin; 09-13-2007 at 09:31 PM.
I suspect that there is a considerable distortion of the
available light's color balance at the forest floor where
little if any direct sunlight may be visible.
The usual B&W films are color balanced for tungsten...snip Dan
They are? Anyway, having done B&W under 300 feet or so redwoods for the past 30 years, I have never worried about it a bit. And unless one is doing some strange highly detailed scientific study, I see no reason to give it a second thought.
The ambient light of an overcast day, and in shadows, will have a ~ higher color temperature (to something over 10,000K) - be "bluer" than direct sunlight, ~ 5500/ 6000K.
Given the spectral sensitivity of modern black and white films, I would determine filtration by the "look" of the finished product, not color temperature.
The ambient light of an overcast day, and in shadows, will have a ~ higher color temperature (to something over 10,000K) - be "bluer" than direct sunlight, ~ 5500/ 6000K.
Given the spectral sensitivity of modern black and white films, I would determine filtration by the "look" of the finished product, not color temperature.
Looks like I went out too far on that limb afterall. At least I had a disclaimer . Thanks Ed for the correction.
Chuck
__________________
"Photography is an illusion. It is amazing that human beings consider a photograph to be a representation of reality."
---John Sexton
They are? Anyway, having done B&W under 300 feet or so
redwoods for the past 30 years, I have never worried about
it a bit. And unless one is doing some strange highly detailed
scientific study, I see no reason to give it a second thought.
Vaughn
Apparently the manufacturers of film have never managed to
make film as red and or green sensitive as it is blue sensitive.
So the spectral sensitivity is balanced across a band around
2800K tungsten.
As for filtration under the canopy my only concern is image
fidelity. For example I've photos where a trail of rock and
earth is less seperable from surrounding green flora than
I judge true to the scene. Dan
Apparently the manufacturers of film have never managed to
make film as red and or green sensitive as it is blue sensitive.
So the spectral sensitivity is balanced across a band around
2800K tungsten.
As for filtration under the canopy my only concern is image
fidelity. For example I've photos where a trail of rock and
earth is less seperable from surrounding green flora than
I judge true to the scene. Dan
Dear Dan,
Um...
Film is inherently sensitive to blue/violet/ultraviolet. Dye sensitization extends that to green/yellow (ortho), orange/red (pan) red and even near IR (hyperpan, extended red).
Filtration allows you to differentiate and pair of reasonably different colours. This is not the same as 'being sensitized to tungsten'.
In fact, if you think about it, as tungsten is much redder than daylight, and many films are fractionally slower to tungsten than to daylight, the statement that B+W films are 'sensitized to tungsten' comes very close to sheer nonsense.
B&W Color Balance Under the Forest Canopy 
Linear Mode
