SBR - Colour film

[delphine]

SBR - Colour negative

I need your input on this one.

It all starts with me lying down on the pavement on a terrasse overlooking the Alhambra in Spain, with the sun facing me, some fantastic trees and people walking towards me as they were walking out of the terrasse or square.

I was spotmetering the scene, and I had pretty much in mind the photograph that I wanted when I spotmetered it. I was surprised by the result, as the area that I had anticipated to show as extremely black is showing dark with clearly visible details and texture.
Unfortunately, I can't remember the EV reading that I got. As the sun was facing me I had a very large SBR range. I metered the scene so that people would be silhouettes and to have some detail on the titles of the terrasse. People were a good 2.5 stop lower than my reference point.

Anyway, I am assessing the result of the photography off a scan image as I just got the film processed and did not get a contact print. So I am now facing a big dilemma and a few questions:
- what is the SBR of the negative film itself?
- for a black area like a silhouette, which how many stop under the medium grey do you position the black area?
- were the people that I expected to show in black, reading a good 1 to 1.5 stop over because I am assessing the photo on a digital output?
- what is the SBR of the negative film once scanned? is it different from the SBR of the negative film itself?
- how about the result a wet print? if I was to process the photo in a darkroom, what would be my new SBR?

I am explaining myself very poorly... but I am getting myself slightly confused over this shot.

Thank you !

 

[delphine]

I need your input on this one.

It all starts with me lying down on the pavement on a terrasse overlooking the Alhambra in Spain, with the sun facing me, some fantastic trees and people walking towards me as they were walking out of the terrasse or square.

I was spotmetering the scene, and I had pretty much in mind the photograph that I wanted when I spotmetered it. I was surprised by the result, as the area that I had anticipated to show as extremely black is showing dark with clearly visible details and texture.
Unfortunately, I can't remember the EV reading that I got. As the sun was facing me I had a very large SBR range. I metered the scene so that people would be silhouettes and to have some detail on the titles of the terrasse. People were a good 2.5 stop lower than my reference point.

Anyway, I am assessing the result of the photography off a scan image as I just got the film processed and did not get a contact print. So I am now facing a big dilemma and a few questions:
- what is the SBR of the negative film itself?
- for a black area like a silhouette, which how many stop under the medium grey do you position the black area?
- were the people that I expected to show in black, reading a good 1 to 1.5 stop over because I am assessing the photo on a digital output?
- what is the SBR of the negative film once scanned? is it different from the SBR of the negative film itself?
- how about the result a wet print? if I was to process the photo in a darkroom, what would be my new SBR?

I am explaining myself very poorly... but I am getting myself slightly confused over this shot.

Thank you !

 

[DrPablo]

With your scene, and shooting negative film, if your major subjects are people, I would suggest metering off your subjects and exposing them either as metered (i.e. middle gray) or maximum one stop darker than metered. Caucasian skin should usually fall on zone 6 (one stop brighter than middle gray), but it might be more realistic to put them on zone 4 or 5 with strong backlighting. Better to blow out some background and keep the people looking realistic than to have them silhouetted and unrecognizable. If your highlights really are 8 stops above your backlit subjects (that you're placing on zone 4 or 5), you can ask the lab to pull a couple stops for you to reign in the highlights.


If I'm not mistaken, SBR really only applies to the original scene and not the negative.

A negative will produce a certain density range in response to its exposure, but the density range will be further modulated by how it's developed.

A negative, or better yet a slide, can have a pretty reasonable dynamic range if viewed on a bright light table with transmitted light. A print will have a lower dynamic range because the light is reflected. This is notwithstanding any printing or processing effects you use to modify contrast, or if you use a high contrast glossy paper versus a lower contrast matte paper.

If your original scene had a 10 stop dynamic range, your ultimate print never will. That's not the point. The point is to capture detail and transmit it to a lower contrast output in a way that preserves tonal relationships.

In other words, if your highlights are at EV 14 and shadows at EV 4, then on paper that EV 14 may be paper white and the shadows may be at the paper's Dmax (i.e. as black as it can get). If you aim a spot meter at that paper, you'll find that the Dmin and Dmax of the paper are nowhere near 10 stops. But it's ok -- you've made a print that looks like 10 stops by preserving a compelling contrast range.

 

[delphine]

Sorry, I am not too sure as to how to close this thread, somebody addressed my question in the general discussion / exposure forum.
Please don't respond here.

 

[jd callow]

I merged the threads so people can post to their hearts desire.

 

[delphine]

You sort of answer my question Paul.

Let me ask you another one. How many stops below zone 5 do you place a silhouette? What is throwing me out is that the traditional system would refer to -5 as you do since you are refering to a 10 stop dynamic range. However, I read the color zone system (chromazone) and it would put it down to -2.5. This is because overall, Chromazone places the shadow and highlight values at -2.5 and + 2.5 max. And it locates the contrast range for detail areas in between -1 and + 1.5.

Thank you for input on this

 

[Chan Tran]

You have about 10 stop dynamic range on the film but when you print on paper if you get 5 stops you're lucky. If you make a print and your Zone V exposure is about medium gray on the print then -2.5 stop would look almost pure black.

 

[jd callow]

I believe that Chan is correct.

 

[percepts]

for colour negative film (which your question was about yes?) base your exposure on colour negative film being able to accept approx 7 stop range. That means each zone in a 10 zone system is 7 divided by 10 which equals 0.7 of a stop.
So zone 3 is two zones less than your metered area so it would be 1.4 stops less exposure required. Zone 0 would be five zones difference which would be 3.5 stops less exposure.

For colour transparency (chromes) which I guess your chromazone book is talking about you would use a 5 stop range and so each zone of 10 zone system would be 5 divided by 10 which equals .5 of a stop per zone. So here zone zero would five zones less than metered area and five times .5 is 2.5

So your chromazone system applies to transparency and not colour negative.

For colour negative use a 7 stop dynamic range. Therefore to place your silhouette on black or zone zero, you meter silhouette and place on zone 0 which is 5 zones less than metered reading and 5 times .7 is 3.5 stops less exposure.

note that not all films are equal and you may find that some colour neg films accept 8 or 9 stops dynamic range. You will have to test to find that out but as a starting point go with 7 stop range.

 

[delphine]

Percepts - I think that you've hit it spot on, and you've just pointed out right on as to why I got mega confused.

I think I need to digest your answer, I may come back and nag you with more questions though.

 

[percepts]

Also note that for B+W films, the manufacturers development guide is NOT generally designed for a 10 stop dynamic range. It is more in line with colour neg film. i.e. 7 or 8 stops dynamic range. This why zone system workers have to play around with film speed and dev times so that a 10 zone system with each zone equalling one stop fits the paper exactly. Problem is that AA's numbers of LogD 1.3 for zone VIII is way off what is required for grade 2 paper. A zone X neg with a density of approx logD 1.2 is about right. So there is a huge anomally in the zone system which as yet is unexplained to me. Not that it matters since if you test properly, you will get to where you want to be.

 

[percepts]

Regarding you query about scanning. Most scanners have a quoted Dmax figure. The magic figure is Dmax 4.0. This is because the densest transparencies such as Fuji velvia have a Dmax of around 4. i.e. a solid black in Velvia is around logD 4. Problem is that these cheap flatbed scanners over state what they are capable of and dense areas usually suffer from a lot signal noise. However, since B+W negs don't normally have density of greater than 2 and colour negs are also well within the capability of the scanner, you should be able to scan either without getting significant signal noise. For trannies that noise will be in the shadows and may not be visible but for negs it will be in the highlights and if it exists it will be visible.
Also remember that because your neg dynamic range does not fit the scanner dynamic range, you have to tell the scan software to compensate which is usually done by setting black and white points with your scan software. (if its any good). So you should be able to scan your colour negs without a problem but it depends on your set up.
Also your software has to remove the neg colour cast effectively which can be a real PITA.

So to answer your question directly, your scanner is probably not the problem but it could be the way you have used it that is.

Apologies for talking D*****L but everyone scans for the web (don't they?).

 

[Sirius Glass]

SBR is not in the LOAA. Maybe, maybe I would understand what the heck this thread was about if I knew what SBR meant. :confused: Hello is anybody home?

Steve

 

[Helen B]

Steve,

SBR stands for subject brightness range - or subject luminance range.

Delphine,

This thread (there was a url link here which no longer exists) covers some of the things you are asking about.

I give two examples of colour negative films: Kodak 100UC and Fuji Pro 160S. The 100UC is capable of recording detail over a brightness range of about twelve stops. On the negative this is represented by a density range of a little over 2.0 in each layer (with a DMax of over 3.0 because of the base density in the blue-sensitive layer).

If you made a (traditional process) print material to match that (ie capable of keeping detail over the full density range of the negative) then straight prints would look very dull and flat. The equivalent of twelve stops of subject brightness would be reduced to the six or seven stops that glossy paper brightness covers.

Therefore the characteristic curve of the paper is designed to need only a part of the density range of the negative to achieve a full range of tones on the paper. In this way the contrast we percieve looking at the print looks similar to the contrast we percieve looking at the real scene - about seven stops of subject brightness range gets converted to about seven stops of print brightness range. It is easier to show graphically than to describe - the old thread I gave the link to has a few graphs in it.

Scanning is a different matter, and this is probably not the best place to go into detail. Here is a link to a thread on the LF Forum that might answer that part of your question.

Best,
Helen

 

[delphine]

If you made a (traditional process) print material to match that (ie capable of keeping detail over the full density range of the negative) then straight prints would look very dull and flat. The equivalent of twelve stops of subject brightness would be reduced to the six or seven stops that glossy paper brightness covers.

Helen, I think that I am with you. If I understand what you are saying only 5 or 6 stops of the neg gets captured on the photographic paper, as opposed to capturing them all and compressing them sort of say in 5 to 6 stops on the photographic paper.
Did I understand you correctly?

With reference to your reference quoted above. If 12 stops of SB was reduced to 6 stops of paper brightness, wouldn't it look over contrasty as opposed to dull and flat?
Do you mind coming back on that one point.

Do you know of a book or hyperlink where I could find all of this explained with diagrams and an introduction to reading curves.

I think you are awesome, and I apologise if I made a mess with your nicely worded and thorough explanation

Best, D

 

[Helen B]

Helen, I think that I am with you. If I understand what you are saying only 5 or 6 stops of the neg gets captured on the photographic paper, as opposed to capturing them all and compressing them sort of say in 5 to 6 stops on the photographic paper.
Did I understand you correctly?

Yes. The film can have a wider density range than the paper's dynamic range, so the paper responds to a part of the film's characteristic curve rather than the whole of it. The exposure given during printing determines which part of the film's characteristic curve is used (masking, dodging etc alter this exposure locally).

If 12 stops of SB was reduced to 6 stops of paper brightness, wouldn't it look over contrasty as opposed to dull and flat?

A scene that had 12 stops of difference between the darkest shadow and the brightest highlight now only has 6 or 7 stops in the print - ie the highlight that was 12 stops brighter than the darkest shadow is now only 6 stops brighter. If the paper was matched that way, then a scene with less than 12 stops of SB would produce a print with less than 6 stops of print brightness - this would not be pleasing. There is some variation in colour paper contrast, but not nearly as much as there is with graded B&W paper.

The usual thing to do with scenes of high brightness range is to try to maintain local contrast by masking, dodging and burning etc.

I'll think about what other explanatory references there might be - and hope that someone else chimes in.

Best,
Helen