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class="Paragraph" Lighting For Black

Published : 19th April 2004


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


class="Paragraph"
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