> Exactly! Why for any reason accept the camera's version of B&W? It
> started from the same raw data available to you to process as you desire.
I was home last night and took a few minutes to stare and compare the
in-camera to an in-computer conversion of the unfiltered shot.
Something totally strange happened. I'll blame it on the extreme
temperatures or something, but there was little difference between the
conversions.
The scene was a bright sunny summer afternoon with puffy clouds. The
sun angle was high but about 45 degrees behind and to my right. The
picture included grass, gravel, water, rocks, trees and sky. A classic
mid-afternoon scene. To my eyes, this was a typical "Sunny 16"
setting. According to the Sekonic L-508, it was closer to a "Hazy 11".
According to the image files, it was a "Hazy 11". This is one of those
situations where a B&W image is definitely enhanced by color filtering
to counter the haze.
With the normal unfiltered RAW file conversion, I did the monochrome
conversion in post using the standard red, green, yellow, orange, blue
and cyan settings. Remarkably, there was little difference between
the images. This had me puzzled. So, it took a little deconstructing
to see what went wrong. Usually, selecting a red filter or a green
filter will yield massively different images, but in this case they
were almost the same.
We are in a drought here in Iowa. There are places that have gotten
rains and places that haven't. Within this scene, the green vegitation
looks green to the eyes, but the camera was certainly seeing the brown
coming through. The actual percentage of green grass to brown grass
was such that in the filtered image, they counteracted each other. One
leaf would darken, while another would lighten, cancelling out the
overall effect. As to the sky, the haze was great enough that the
extent of the change from one extreme to the other in the "blue sky"
was no more than a half-stop. The red filter (either on-lens or
post-process) had minimal, but visible, difference. Even the polarizer
had little effect.
I reshot this Monday evening at a different location. Unfortunately,
the clouds had cleared off, but the haze remained. I got differences,
but again, they weren't revealing what was expected in the tests.
It's not that I just rolled off the turnip truck last week. I know
what these filters do. I do know my B&W. But stuff just wasn't doing
what I expected it to do. So, that's where my engineering mind kicks
in and tries to figure out what happened or didn't happen.
Several thoughts:
1. The haze layer was great enough to minimize the differences.
2. The digital sensor has greater or lesser visibility of the UV/IR
spectrum than film which defeated the effect of the filters.
3. The Panasonic DMC-L1 is lousy for B&W conversions.
As to the first point, this is entirely possible. The visiblity
conditions were less than 10 miles.
The second point is one that we can look at the spec sheets on to
determine and then speculate on the effect. Testing can confirm.
The third point was easily tested. I pulled up several other pictures
that were representative of this scene and in the editor, I converted
to monochrome using various color filters and it responded as we would
expect.
There may be other causes which I'm open to discussing. Regardless, it
looks like I'll just have to wait for a better day, which isn't so hot
and soupy, to prove my theories.
AG Schnozz
--
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
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