A couple weeks ago I wrapped up a contracting job where I sold and
installed a sound system, stage lighting and large flat-screen tv
system for a multi-purpose rental venue. For the stage lighting, I
installed full-color LED lights. The lights use those combo
multi-color LEDs. Some are four channel (Red, Green, Blue, Amber) and
Some are six channel (Red, Green, Blue, Amber, White, UV). The UV
channel provides "black light" functionality.
One of the battles every photographer has fought is LED stage lighting
and how hard it is to photograph in it without clipping. And,
depending on the camera, you'll get really horrible color casts. This
is one of those cases where film actually is far superior than digital
for capture.
But why?
I think I figured out part of the problem. The LED lights produce
copious amounts of near-UV light. (I wear bright neon colored shoes,
so it was easy to see the black-light effect even with the UV channel
turned off). Most digital cameras, to one degree or another, have a
secondary sensitivity bump down right near the UV end of the visible
spectrum. In the case of the classic E-1, this secondary bump is
present in the red channel. This way, a violet colored subject will
capture as purple, whereas some cameras (and films) will capture it as
blue. Older Nikons were especially prone to the blue-shift to an
extreme.
At issue is how the camera sees and captures this near-UV illumination
caused by LED lighting. I'm noticing a general color fogging that
can't be mapped out during raw conversion. If a person is wearing
stage makeup, the result can be that it looks like you yanked the
Clarity Slider backwards 50 points and has a Trump-color to the skin.
No stage makeup and you'll get green-blue pastel zombie apocalypse.
Now, understand that I almost never use skylight or UV filters on my
lenses. They go commando. It may be that for LED stage lighting, I
need to try using a UV filter.
Thoughts?
AG (purple and glowing) Schnozz
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