I got a lesson on the effect of spectral sensitivity when
shooting some portraits on Technical Pan. T Pan had extended red
sensitivity, not just more sensitive to visible red but it
extended into the near IR. Very odd skin tones, not just a bit
washed out but almost transparent. probably flattering for some
subjects.
Its too bad there has not been good ortho for a long time. I
think this is how (just lost a name, famous portrait
photographer) got his "look". I think he used ortho for men thus
exaggerating skin texture. probably filters could accomplish the
same thing but I am not sure the film was not unique. Back in
the bad old days there was plenty of ortho. For one thing it was
standard for press work both because it tended to exaggerate some
types of detail and because it could be processed under a red light.
On 7/21/2021 3:58 PM, BOB KISS (Redacted sender bobkiss for
DMARC) wrote:
DEAR RICHARD,
You are correct why there was a different speed rating for daylight and tungsten...in the past...the spectral sensitivity of selenium.But the Kodak data sheet still has this difference and, in the 21st century, one can only put it down to the spectral sensitivity of the film...perhaps less red sensitivity...thus a bit slower in tungsten light which has a rather large percentage of red in its grey body curve.There may actually be an aesthetic reason for this:high red sens film tends to render skin tones much lighter where as film with less red sens tends to give them a little more tone.An extreme example of this is the classic Hollywood portrait shot with Ortho film which was green and blue sens (and UV like all Ag-X materials) but very little red sens yielding those amazing women's and men's portraits!Of course, the pancake makeup applied with rollers didn't hurt either!LOL!!!
CHEERS!
BOB
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx [mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of `Richard Knoppow
Sent: Wednesday, July 21, 2021 6:06 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Cinestill Double-XX
Another thought: Until some time ago, not sure when, B&W
films had both daylight and tungsten speeds. The reason for this
is partly that the most common type of light meter used a
Selenium cell. Selenium is more sensitive to red than to blue or
green so it tends to read high for tungsten light, which is
strongly red. The high reading is combined with the typical
spectral characteristic of panchromatic film of being more
sensitive to blue than to red so the two combine to require a
higher average exposure to tungsten light. More modern meters
tend to have flatter spectral curves. Its always worth looking at
the wedge spectrograms for film. Kodak always made them available
but they may take some searching for now. Its also worth finding
out what the spectral response of your exposure meter is. This
all goes to the principle I was taught very early which is to
know what you are measuring. What exactly makes the "meter" read.
Sometimes not what you think.
On 7/21/2021 2:35 PM, `Richard Knoppow wrote:
> A
Richard Knoppow
dickburk@xxxxxxxxxxxxx
WB6KBL
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