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In The Zone.......or not?

JGH

New member
Hi all, it was suggested to me by another forum user that i could try and ask this question in this area.

Over the last few months i have ben experimenting with the zone system and have been fairly confident that i was getting the correct results.
I have been zeroing my meter on a particular tone in the image which would equal zone V and then adding or subtracting by whatever stops necassary to place that tone in the desired zone.
Everything is fine when i do that and if i have placed it correctly i get the desired effect. The problem i now have is i cannot seem to relate my on camera histogram to the zone system. let me explain. If i add 2 stops to a tone that i zeroed to zone 5 (centre of the histogram) then that tone becomes a zone VII but when i look at the histogram on the camera it has nearly reached the right hand side (this is fine as it has not blown out). Now IF the histogram on the camera is representing the entire zone system (from 0 through to X) wouldnt the histogram only be reaching 2/3rds to 3/4 of the way along the right hand side?
Checking the LAB luminosity numbers in PS CS5 for the modified zone shows that it is around 85 - 92ish when technically it should be in the 70's.

I have got to the point were i have confused myself because i am thinking to much and need some help from people who can shed some light on what i have overlooked.
(i am using Olympus E30 BTW)

I hope there is someone out there with the patients to help me with this because even though i am getting good exposures it would help to understand why the histogram goes to zone 8 or 9 (sometimes 10) when i only dialled in 2 stops of compensation.
I think what i have said makes sense? Please help !!!

Thanks

J
 

routlaw

Member
Hello J

While I have no experience with the Oly E30 and know even less than that about this particular camera I feel you are attempting to do something that really is not possible with digital imaging. Effectively there really is no direct translation from analog Zone system of photography to digital imaging at least that I am aware of and I have been using digital cameras of all kinds since the mid 90's, well over 10 years.

First off digital sensors are just much more linear than film based analog zone system, furthermore by overexposing in the way you describe you will eventually depending on the scene completely blow out the highlights and on a sensor and once those are gone they are completely gone with no hope of retrieving them.

To complicate the situation the camera you are using might not even have a 10 stop dynamic/exposure range. Certainly most MFDB's have this, as does my Betterlight scan back and the D3x and D3 series of cameras do. Even then you simply cannot make the same assumptions or implement a workflow like the Zone system and film. Add to that what ever recipe your raw file converter might be implementing which contracts (usually) the dynamic range of the sensor and thus pushing you even further from the zone system.

My suggestion is learn the limitations and attributes of your camera and raw file converter of choice and deal with it within those parameters.

I hope this helps.

Rob
 

JGH

New member
Hi Rob, thanks for your reply. My camera only has around 8.9 stops of DR @iso 200 so technically it cant see all of the zones however through further reading i stumbled upon an explanation that may be a solution to my problem. It was something along the lines of digital cameras do not require all the zones in the zone system as zones 0 & 1 and zones 9 & 10 were for the paper printing process and a digital camera effectivly sees zone 2 as pure black and zone 8 as pure white which leaves zones 3 to 7. Thats 5 stops !!! i know digital cameras can see more than that so that it a little confusing however 5 stops from end to end does seem to ring true with both my cameras because if when placing a zone i under or over expose by 2 stops the histogram will just sit before the left or right edges.
So maybe the histogram on a camera only shows these 5 stop values?
I dont know this for sure and this is just what i read. I was testing some more this evening and it seems to be about correct. Any more than 2 stops either way blows the highlight or shadows. I can live with that. I should just be happy im getting good exposures and not be so anal about all the numbers !!!!

J
 

Lars

Active member
I'm with Anders, ETTR is the way to go. Keep in mind that that Zone system was created in the absence of a histogram, and for the purpose of using the nonlinear properties of film and paper to control hardness, as much as exposure, in the wet darkroom. Shooting digital, we can control contrast in post, and the instant histogram makes a spotmeter almost redundant.

If you still want to think about the camera histogram in terms of zones, consider this: What is the scale of the histogram? It's certainly not logarithmic, so zones will not be evenly spaced. A qualified guess is that it's gamma-coded using the 2.2 gamma of sRGB and AdobeRGB colorspaces.

Gamma 2.2 places the middle of the scale as 21%, slightly over the 18% gray standard commonly used but acceptable for a midtone level. This also means that you have 2.2 steps of latitude to the right side of the histogram, meaning it clips at zone 7.2, so if you want to find zone VIII, IX or X then you are looking in vain. Usually the camera handles a bit more than 7.2 as it uses the extra highlight range of the sensor to avoid clipping, but with only zone V, VI and VII to use on the highlight side it gets a bit awkward.

What all this means is that you basically have the same DR as slide film on the highlight side. In the shadows you have a lot more though.

Just about now you should start asking yourself "OK, why am I considering using the zone system again?" All you need to think about is where to place the highlights and midtones, and let the shadows fall where they may.

Put your effort into getting a good feel for metering modes and manual exposure instead, together with a close eye on the histogram.
 

Shashin

Well-known member
The answer is simple, the gamma or contrast index of the film and sensor are different. It has nothing to do with the linearity of the film/sensor response. Digital sensor do not have a latitude of negative films and so the gamma is higher which mean a one stop change will move the resulting tone into a higher or lower zone than you anticipate. If you want to use a digital camera and the zone system, and there is not technical reason you cannot, then you are going to have to redefine the zone scale for the sensor.

The other side of this is since you can see your histogram and image after you take the picture, why do you want to use the Zone System? Film photographers did not have this option and so the Zone System was a way to control and anticipate results at any one scene.
 

Anders_HK

Member
If you want to use a digital camera and the zone system, and there is not technical reason you cannot, then you are going to have to redefine the zone scale for the sensor..
The purpose of the zone system at capture (film or digital) is to enable full control over image data at capture, and to enable optimizing the "negative" for a given scene by manual control at capture. Digital, B&W, slides, polaroid etc only means that the zone system needs to be applied on basis of the character and response of the media, which was what Ansel did for B&W, polaroid etc. It does not necessarily mean that what we place on zone VII will be same zone in the print. Nor was it for ansel when he use his expansion techniques in processing of B&W...
I think you are correct, the gamma makes difference. However the latitude depends on the sensor and camera/back.


Critical when using the zone system at capture for digital is to not exceed what is an accaptable bright level, hence expose towards the right, ETTR. For B&W Ansel Adams exposed for the shadows (hence ETTL, exposed towards the left) and later processed for the highlights. With digital we need to ETTR in order to optimize the image info at capture (assuming shooting RAW, and assuming the DR of the scenes requires us to do so, or else there is no need to ETTR). With digital we process for both the highlights and shadows and far more pending on the scene.

The other side of this is since you can see your histogram and image after you take the picture, why do you want to use the Zone System? Film photographers did not have this option and so the Zone System was a way to control and anticipate results at any one scene.
Histogram = "after you take the picture" , a.k.a. trial and error.

Zone system = before you take the picture and can enable us to to in our minds eye visualize the scene using a spot meter for the image data we will capture, and thereby quickly control the precise optimum exposure for a given scene.

My view is frank that things are same as Ansel described... only applied to a different media than the ones he applied to. :D
 

Shashin

Well-known member
Anders, the more things change, the more they remain the same. Basically, everything is applied sensitometry. And there are many ways to get to the "correct" exposure. Even ETTR was a technique for film photographers, except they did not have a histogram with which to give it a name. And it had the same benefits and problems.

I am not quite confident how "precise" a spot meter was. Certainly I could get great exposures with one, but that was after a great deal of trial and error learning to see and meter. Digital cameras just use the first exposure as the "meter reading." Perhaps Polaroids would be a better analogy.

But every photographer I know mixes a little black magic with science for "their" exposures.
 
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