In the thread "Tiny Flashes of Light" it was written
:
>> Nick (If you light it you
see it) Hoffman NYC
> Yes. The mirrors will be seen long before the black is
gray
this exchange reminded me of a phenomenon that I've been playing
with for some time. I find that the best way to get truly
dark blacks is to light them to just the proper level of underexposure
for the stock you are shooting. It seems that shooting areas
that are too dramatically underexposed will tend to cause
the blacks to get muddy. This seems counterintuitive and I've
always wondered what the underlying explanation of it is.
Has anyone else found this to be the case? It is a phenomenon
that has interested me for some time but I haven't really
given it enough though to generate a suitable explanation.
Any thoughts from the list?
-David C. Smith
LA/OC D.P.
One trick is to put something bright next to the thing you
want to be black. Bill Fraker did this on the film "War
Games". He wanted the giant War Room screens to have
deep blacks so he surrounded them with a thin bright light.
Bob Hayes
David C. Smith wrote:
>I find that the best way to
get truly dark blacks is to light them to just the >proper
level of underexposure for the stock you are shooting.
I seem to remember reading that minimum light levels do in
fact render blacks blacker than if there is no light at all.
My only problem is I can't seem to find a reference to this
in any of the books I have...I could have sworn it was mentioned
in Ansel Adams' book entitled The Negative. I just can't seem
to find it.
>...This seems counterintuitive...
Film reacts strangely to certain situations. If you dramatically
overexpose film negative, instead of remaining pure white,
it can go black (a shot containing the sun can show the itself
sun as black or grey). I believe this is know as solarization,
though other than in books I have NEVER heard of anyone having
to deal with this. Another funny thing is what happens during
long exposures. Due to some function of film's ability to
absorb light, normal exposure calculations which result in
long exposures (of 1 second or more) require one to leave
the shutter open longer than initially calculated. This is
knows as know as the reciprocity effect. There are tables
that list the EXTRA TIME one needs to expose the film to render
a shot properly.
Piotr Jagninski
Gaffer / New York City
Gee, I've gotten night skies black without lighting them or
using 50,000 square feet of foamcore.
(although given the amount of ambient 'light pollution' almost
everywhere now I dunno, a lot of dark skies are "prelit"
....)
Really, expose for healthy enuf printer lights & take
advantage of the eye's lateral brightness adaptation trick
as was suggested....
Sam Wells
Piotr Jagninski writes:
>If you dramatically overexpose
film negative, instead of remaining pure >white, it can go
black (a shot containing the sun can show the itself sun >as
black or grey).
Solarization involves exposing negative film to light during
the development process. This affects different parts of the
image differently, depending on density and other factors.
This should not be confused with the highly controlled re-exposure
to light that's part of the processing of reversal (positive)
film : In the first developer, a negative image is formed,
then the re-exposure is made, which "prints" that
negative image onto a deeper layer of the emulsion. Then the
negative image is bleached out and the positive image is developed.
That's a simplified explanation (which is all I'm capable
of), and describes the black-and-white reversal process only.
But it should help you to see why solarization can produce
an image that's negative in some places and positive in others.
Dan Drasin
Producer/DP
Marin County, CA
If the medium you're displaying on is a video screen, you
must have a bright area in the frame in order to get a rich
"black". A frame of video on a CRT will tend to
look dark grey if there is no bright area in the same frame.
This is due to the nature of most televisions monitors which
have something called a "DC restoration circuit"
which pumps up the video level as it controls the voltage
to the video "guns".
There is also a visual interaction which causes the eye to
consider a shade (or color) in relationship to its surroundings.
When deciding if something is bright or dark, your visual
mechanism asks the question "as compared to what?"
For example: Is a car headlight bright? (Is it night time
or noon on a clear summer day?) A frame of video is viewed
the same way. Contrast provides the foil to exaggerate the
quality of relative brightness or darkness. This visual effect
holds true regardless of how the image is displayed. That
should help you get the crisp blacks you desire.
Bruce "We never elected him the first time" Aleksander
LD/DP
ABC / Houston
>I seem to remember reading that
minimum light levels do in fact render >blacks blacker than
if there is no light at all. My only problem is I can't >seem
to find a reference to this in any of the books I have...
William Fraker, John Alonzo, etc. used to say this -- you
had to add some light into the blacks to expose some of the
silver there, etc. I don't really believe this is true because
any light you add to the shadows creates DENSITY on the negative,
which is the opposite of black by definition. What really
matters is density of the key area so that you can print the
image at higher printing lights, making the blacks richer
and deeper.
Fraker did say something that is definitely true in that if
you have a bright highlight, it makes the surrounding black
area look blacker in comparison. He used to put a tweenie
or something in the frame at night, far away, to create this
hot spot in the frame to make the blacks look darker. Nestor
Almendros had a similar observation in that if a shot is entirely
underexposed, it looks murky -- but if there is one small
area of brightness, it makes the image look less dark, or
more intentionally dark at least, because now your eye has
a bright reference in the frame to balance against the darkness.
David Mullen
Cinematographer / L.A.
>I find that the best way to
get truly dark blacks is to light them to just the >proper
level of underexposure for the stock you are shooting.
>I seem to remember reading that
minimum light levels do in fact render >blacks blacker than
if there is no light at all....
How black the black areas are is a function of printing exposure.
If the overall neg. is thin the blacks will print muddy because
the printing exposure had to be reduced to keep from darkening
the highlights. OTOH, if you shoot a heavier neg. the printing
exposure is increased to print through the highlights and
the clear areas get more exposure. I don't know of any study
that indicates the need for some minimal exposure to produce
black. Perhaps that's a misinterpretation of the fact that
you must have a certain minimum overall density if you want
the blacks to print black. Basically, clear film prints black
if the highlights have sufficient density to permit a normal
or better printing exposure.
>...Film reacts strangely to
certain situations. If you dramatically >overexpose film negative,
instead of remaining pure white, it can go >black (a shot containing
the sun can show the itself sun as black or >grey).
That's true. Very heavy exposure--perhaps 10,000x normal--will
cause a reversal of those areas, called solarization. It's
pretty difficult to achieve today on any printable neg., but
you see it occasionally on old, turn of the 20th cent. night
time exposures where a bright light source is in shot, or
pictures that include the sun. A somewhat similar looking
effect that is created by fogging the partially developed
film, then continuing development, is called the Sabattier
effect, tho' it is often misnamed solarization.
>...Another funny thing is what
happens during long exposures. Due to >some function of film's
ability to absorb light, normal exposure >calculations which
result in long exposures (of 1 second or more) >require one
to leave the shutter open longer than initially calculated.
Reciprocity failure results when the input of photons is so
low that those halogen atoms that were freed from the silver
halide, making the resulting silver ion developable, are able
to recombine with the ion to reform silver halide. That tends
to nullify some of the latent image. The corrections are usually
given in terms of additional exposure time, but that always
seemed to me to be wrong headed. I think opening the aperture
makes more sense, if you can afford it.
Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614
Wade Ramsey writes:
>Reciprocity failure results
when the input of photons is so low that those >halogen atoms
that were freed from the silver halide, making the >resulting
silver ion developable, are able to recombine with the ion
to >reform silver halide.
Yes, but...
Reciprocity failure can occur with extremely brief exposures
even at very high light levels, or with long exposures at
very low light levels. It takes both a minimum amount of time
and a minimum of intensity for the photons to activate a given
emulsion.
Brian Heller
IA 600 DP
>William Fraker, John Alonzo,
etc. used to say this -- you had to add >some light into the
blacks to expose some of the silver there
Yeah, but that's the reason why we all religiously overexpose
1/2-2/3 stop to get some of that black on the negs (instead
of the murky brown), right?
Cheers
Martin Heffels
Filmmaker/DP/Editor
Sydney, Australia
>Yeah, but that's the reason
why we all religiously overexpose 1/2-2/3 >stop to get some
of that black on the negs (instead of the murky brown), >right?
People always said it was good to have a nice thickly exposed
neg. But I do believe it is a bit of "old school"
as I think it mostly applied to shooting with the older stocks
and printing for projection. It was also a common idea to
err on the side of overexposure rather than underexposure.
I'm not certain that applies to modern stocks and contemporary
video transfer processes.
My experience has been that overexposure and printing down
increases the contrast a bit which may make the blacks seem
richer.
Jim Sofranko
NY/DP
It was good to have a nice thickly exposed neg. But I do believe
it is a bit of "old school".
A pretty big deal D.O.P. I worked with...said he always established
strong blacks so that they couldn't Fool so much with the
contrast of the image in post. Or if it was a television commercial...
T.V. channels were renown for messing with the black levels.
I had to admit that when I worked in Television we ran a 10%
black level .. because we got more hours out of the final
transmitter Tube.
Graham Rutherford
Gaffer Australia
>Reciprocity failure can occur
with extremely brief exposures even at >very high light levels,
or with long exposures at very low light levels.
True. In the case of extremely brief exposures at high light
levels, the photons bombard the silver halide so heavily the
crystals can't respond quickly enough to take full advantage
of the exposure.
Generally speaking, exposure times between 1 second and 1/1000
second behave reciprocally. Beyond those limits many emulsions
will show failure, but it varies with different formulas.
Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Recently, I fought and lost this battle; to make a rich black
background I asked for a grey seamless background ( around
75%), and the plan was to keep light off the seamless background
until it was black in relation to the key.
The camera owner (sometimes called DP) insisted that that
was too much work and a black background was used. The blacks
were muddy. In theory, one could use a white background, with
"no" light on it to get a black background, but
spill from the key and fill make that really hard. I've had
good luck with a grey background, letting a small, small,
amount of room spill light it. Meter the background to place
the grey value in the black, in relation to the key.
Basic zone system stuff.
Dan LaBorde Kentucky
Any black with a slight reduction of your master ped will
produce nice black blacks.
Walter Graff
BlueSky, LLC
Dan LaBorde Kentucky wrote :
>...The camera owner (sometimes
called DP) insisted that that was too >much work and a black
background was used. The blacks were >muddy.
Were you shooting film or video? If film, and an unlighted
black background prints muddy, it simply means that it was
printed up. If the scene in front looks properly exposed on
the print, it was underexposed, requiring the scene to be
printed up, muddying the background. If you'd used the gray
you described under exactly the same conditions you'd have
had a dark gray tone, lighter than the muddy black you got.
If you can underexpose that gray background enough to make
it print black, replacing it with a black background will
NOT give you a muddy tone! Just basic zone system.
Black is black. No exposure is black. Black means no scene
density on the negative, that part of the scene fell on the
toe of the curve. If the highlights are where they are supposed
to be, high on the curve, unexposed film prints black. Anything
that wasn't black will have some neg density and will print
with some tone. If it is a very slight density you won't get
a strong black and that can look muddy--not dark enough to
be black, but not light enough to see the texture.
When blacks print muddy it is simply because the printing
exposure is too low to give the print the density it needs.
Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614
The Kodak website has a very good discussion of exposure and
tone scale :
http://www.kodak.com/US/en/motion/support/h1/structure.shtml
John Pytlak
EI Customer Technical Services
Eastman Kodak Company
http://www.kodak.com/go/motion
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