Metering approach explanation needed.

[galupi20]

Can you tell me if this metering approach of shadows and highlights based on Subject Contrast Range is applicable only to find correct development time or do I have to use it every time i make a meter to take a picture ?

Thanks a lot

Luis


Jul 27, 2008 #15

RobC Member
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There is a persistent myth that over exposure is required to get good shadow detail. This is not necessarily true and entirely dependant of subject contrast range. AA is known primarily as landscape photographer where very often he has bright clouds and dark shadows in the images and where the subject contrast range is great. Result is that he uses a 10 zone system and to make a 10 stop subject from black to white fit onto a negative which then fits directly to paper, you need to overexpose and reduce development from manufacturers recommended times.
So what are manufacturers recommended times based on? Well, usually around a 7 stop range for negative films. That is based on the "average subject" brightness range and not high contrast scenes.
So now take your subject and find out what its range is. You have a spot meter so that should be easy to determine. Since it is indoors I strongly suspect it will be a low contrast subject. Very probably less than 7 stops from black to white unless you have windows or shafts of sunlight coming into the image. For a 7 stop or less subject range you should not be giving additional exposure so expose at ISO speed and use manufacturers recommended times. That will give you the contrast in the negative which will fit the paper.
If you are still getting low contrast negatives, then increase development time 30% and try again and if you are still getting low contrast negatives, then go to ISO 60 or above.

As you know the zone system as says there are zones 0 thru 10. By default each of those zones is 1 stop of exposure. However, the zone system is so flexible that if you have a subject of say only 6 stop range from black to white, then you can say each zone is 1/10 of that range. That would make each zone step 0.6 stops. That means that if you meter what you want on zone 3, then you would reduce exposure by 1.2 stops or 1 1/3 which is close enough. This assumes you have tailored development of your film to fit a 6 stop range.
The same applies for slide film except slide film is high contrast film and out of the box it accepts only 5 to 6 stops brightness range from black to white. Assume 5 stops and therefore you can say each zone is 1/2 stop step. So if you meter what you want on zone 8 then you open up 1 1/2 stops to expose it correctly. A little trial and error is required but that will be pretty close.

So to recap, high contrast scenes need extra exposure and reduced development from manufacturers recommendations (based on a manuafcturers 7 stop range).

Normal contrast scenes require use of manufacturers recommended numbers and low contrast scenes require reduced exposure and increased development.

But all of these require knowing how long to develop for.

For b+W films you should do some print tests:
To calibrate for a 10 stop subject range. Expose an even subject at zone 1 and then the same at zone 9 using 1 stop for each zone step. Print the zone 1 neg until it is just slightly less dark than a max black. Then print the zone 9 neg using the same print time and it should have just a hint of grey.
If its white then reduce development a little (20%) and try again. Iterate until you nail it.

To calibrate for a 7 stop subject range. Repeat the above except make each zone a 0.7 stop step. So exposing for zone 1 would be metered value and then closed down 4 x 0.7 = 2.8 stops ( a little over exposure is best so make it 2.66 stops. i.e. 2/ 2/3). Then expose a zone 9 neg which will be plus 4 x 0.7 from metered value. or rounding up for a little over exposure makes that + 3 stops. And print as above.

To calibrate for a 5 stop subject range. Repeat the above except make each zone a 0.5 stop step. So exposing for zone 1 would be metered value and then closed down 4 x 0.5 = 2 stops. Then expose a zone 9 neg which will be plus 4 x 0.5 = 2 stops from metered value. And print as above to prove development is correct.

Note that a zone 1 neg should have a small amount of density greater than the fb+fog. If the zone 1 neg is same as fb+fog then you need extra exposure (reduce film speed). If zone 1 neg is too dense then less exposure is required (increase film speed).

 

[wiltw]

I presume you read about the Zone System, and now wonder about it. Two key points

1. To fully expoit the Zone Sytem, you need to first use ZS exposure, then process INDIVIDUAL SHOTS on film differently, then print on a suitable grade based upon the negative that resulted.
2. You CAN use 'Zone System of exposure' to help with understanding 'the best' exposure to use in a situation, even without Zone film processing...bt it is NOT 'using the Zone System'!

Now what are YOU trying to accomplish, #1 or #2? Keep in mind that #1 is not practically feasible with roll fim.

 

[galupi20]

Hi wiltw. 1) Thanks for answer. 2) I'm trying to accomplish #1. 3) Are you telling that RobC is only "using" the Zone System of exposure to perform a Film Time Development Test ?

Sorry for my English

Luis

 

[wiltw]

Luis,

I imply needed to verify your intention...as I said, full Zone System virtually requires use of sheet film....will you be doing that?

 

[galupi20]

Yes. I only use 4x5 T-Max 100 for now. Developer D-76 1+1 CPP2 Jobo Expert Drum 3010.

 

[wiltw]

You DO need to know what the dynamic range of the scene measures (min EV to max EV) so you know if 'it fits' the film, or you have to try to compress the DR of the film with suitable alteration of development, or if you will want to broaden the DR to give you richer blacks and brighter white in a narrow DR scene.

Otherwise you are merely shooting with average metering like everyone else and using generic N development for everything shot.

 

[pentaxuser]

If you are still getting low contrast negatives, then increase development time 30% and try again and if you are still getting low contrast negatives, then go to ISO 60 or above.

Can I ask where the ISO 60 came from? Was this from the article where the part you have not quoted contained the ISO of the film being used?

It is just that ISO 60 does not seem to relate to anything in the article you quote

Thanks

pentaxuser

 

[wiltw]

Can I ask where the ISO 60 came from? Was this from the article where the part you have not quoted contained the ISO of the film being used?

It is just that ISO 60 does not seem to relate to anything in the article you quote
Thanks
pentaxuser

In fact, ASA 60 never existed! The traditional sequence of ASA values...

25
32
40
50
64
80
100
125
160

​

 

[138S]

Can you tell me if this metering approach of shadows and highlights based on Subject Contrast Range is applicable only to find correct development time or do I have to use it every time i make a meter to take a picture ?

Thanks a lot

Luis

Yes... RobC is speaking in Zone System terms

In metering YMMV. As you look interested, I'd suggest you read Beyond The Zone System book, first half explains practical sensitometry the second half explains practical metering methods. The important part is the first one.

In Zone System VISUALIZATION is a key concept. The central zones have full detail, the extreme zones (toe / shoulder ) are compressed and detail is damaged. After selecting an exposure, if you inspect the scene with the spot meter you will find wich areas of the scene have an under or over exposure within two spots so they are to be mostly linear and with good detail.

It happens that today's films can be quite linear, and won't totally behave like Zone System is predicting.

At the end with Zone System you use an spot meter, then you adjust exposure to ensure detail in the scene spots you want detail, the exposure you use will take care that those shadows have an underexposure not larger than 2 or 2.5 stops: Expose for the shadows ! and let the highlight be as overexposed as necessary to keep shadow detail.

Then, with the exposure calculated for the shadows, you inspect highlights to see how overexposed they are, it may happen that some interesting highlights are at Z-X, this is overexposed by 5 stops... so you have to do something to avoid too high densities in those +5 too overexposed highlights... what do you do? Develop for the highlights !!

Say you wan't those +5 highlights in Z-VIII, for that you perform a N-2 development, so you place what it was to be +5 at +3 density. With the shorter development shadows will develop mostly the same but you will lower the final density in the highlights. How do you find the N-2 development time? Easy... if it is ISO 400 nominal then find in the Massive Development chart the development time for EI 100, EI 2 stops less for N-2.

You will record that +2 (SBR) extended range, but the compression will require you use a high contrast paper grade in the darkroom to have natural mids, an you will have to manipulate the print, burning highlights and dodging shadows to see the detail in the print. If you scan then you simply bend the curve in S shape.

At -3 underexposure you loss all detail, if you want sadow detail there is no other way than to expose enough, but this may damage highlights... if the case (spot meter) you reduce development to prevent that damage. It is that easy !!

 

[eli griggs]

This is the way I understand the basic work needed to get into the Zone System, and learn to make it work for you.

Others will have other thoughts, so be aware there are several ways to get at it.

You need to shoot a set new grey, white and black reference cards together, preferably on a bright, day, on the shade side of North, with no direct light in the shade or kitting your lens, I also suggest at film speed you intend to use, at F8, if possible, and develop the film with as many different settings as you can get on the roll of film, or box of sheets, to establish, what is for your film, camera, favorite lens and developer combination, zone five or six, and the dynamic range you get when processed to normal.

Once "Normal" is established, double check on both the Negative and Plus factors with Individual sets of rolls, sheets, keyed to the first combinations on the Normal roll of film.

I should mention two, you'll have to do similar with your favorite printing paper and developer, with the time of the paper in the developer at max limit, for example, I like Ansco-130 at three minutes at 70 degrees F, but you'll want to use what you find is best for you.

Take good notes of each exposure, throughout the range on film and paper and with the film, note each shot in both shutter speed and aperture and EI, with whatever meters you have for actual photography.

1 degree Spot Meters are needed in most cases and do no bother with wider spots, as you'll no be able to get the pinpoint readings you'll want in the field.

Also, use a reflective meter on your hand, from your tripod position, so when you do no have a spot meter, you can visualize the effects of sliding up and down the scales, especially in the Normal film, paper, developers base results.

If you have other cameras that have meters that you're no sure will hold to the basic Normal Standard, you can just use the camera meter, to read any difference in settings as you go along making your notes at the same time, so you'll know where those cameras will read in relationship to your spot meter.

This is just one way to approach the Zone System, but you do need to do what it takes to get control of your materials and tools, cameras and lenses.

I won't suggest you do this for all your bodies and lens combination, but with good notes you should be able to quickly locate any errors your process that vary by a stop or more, and correct for them.

Good Luck,
Eli

 

[ic-racer]

If you print with graded paper or multigrade paper, you can forgo some of that and develop most all film for a contrast range around 0.65 to 0.75 depending on enlarger type. In that case, you can print most all subject brightness ranges with paper graded from 00 to 5. Many people have been doing this for years and it works well. Saves a lot of hassle in the field and in the darkroom. I'd highly recommend trying it.

 

[galupi20]

Can I ask where the ISO 60 came from? Was this from the article where the part you have not quoted contained the ISO of the film being used?

It is just that ISO 60 does not seem to relate to anything in the article you quote

Thanks

pentaxuser

https://www.photrio.com/forum/threads/overexpose-and-underdevelop.40602/

 

[Sirius Glass]

Luis,

I imply needed to verify your intention...as I said, full Zone System virtually requires use of sheet film....will you be doing that?

It ain't necessarily so ... I use it with 35mm film and 120 but I only do straight development because modern films not not require N-1, N-2, N+1, N+2, ... since the latitude of film is so wide.

 

[wiltw]

It ain't necessarily so ... I use it with 35mm film and 120 but I only do straight development because modern films not not require N-1, N-2, N+1, N+2, ... since the latitude of film is so wide.

A purist would state you are NOT using the full Zone System as outlined in Ansel Adams book on the topic. You are using part of the Zone System. Like me, you are not a real Zone System practitioner.

 

[Sirius Glass]

A purist would state you are NOT using the full Zone System as outlined in Ansel Adams book on the topic. You are using part of the Zone System. Like me, you are not a real Zone System practitioner.

I use what works for me in the Zone System. Since I can get the results I want without deviating from normal development, there is no reason for me to use the rest of the original description which was formulated for less capable film.

 

[Bill Burk]

I haven’t heard from RobC in a long time. We disagree vehemently on theory. So I can’t clarify his explanations.

If you use TMAX100 at EI64 with spotmeter metering and Zone System placement of exposure readings, you will likely get the same exposure (f/stop and shutter speed) as you would choosing the rated speed (100) with either an averaging meter (auto exposure in an SLR) or incident meter.

Many people create systems for themselves where they change exposure index with different development times. The principles of pushing (underexposing and overdeveloping) logically support using a higher rating, when you need speed. But you don’t have to do that. I would use EI 64 with TMAX100 all the time.

 

[wiltw]

I use what works for me in the Zone System. Since I can get the results I want without deviating from normal development, there is no reason for me to use the rest of the original description which was formulated for less capable film.

I absolutely do NOT disagree in any way...we each have a method which uses a PART of the Zone System, and what we do works for us. But we both are NOT true practitioners of the 'Zone System'. and that applies to the majority of photographers in photography.

True practitioners were a minority even during the lifetime of Ansel Adams and his followers; Fred Picker did not lead a huge following. That is why it is so hard a find good, cogent presentations about it...few explanations that I rhave ead on forums reflect the true practice.

 

[138S]

This is the way I understand the basic work needed to get into the Zone System, and learn to make it work for you.

Yeah... we may use many recipes, but we have two facts: Those crystals not exposed won't develop an image... Overexposed spots may develop a too high density if not adjusting development... From that, we know what we have to do...

 

[Doremus Scudder]

If my first introduction to the Zone System had been the "explanation" in the original post, I would have given up in confusion and despair. Not only does that explanation confuse due to its lack of clarity, it misunderstands basics about the science associated with photography. The Zone System is not rocket science: it's a simplification of the sciences of tone reproduction and sensitometry packaged to make it accessible and usable by anyone with a lick of sense. Trying to overcomplicate things defeats the purpose.

So, Galupi20, let me make a few basic observations and then you can go from there.

First and foremost, the Zone System follows the adage, "Expose for the shadows; develop for the highlights."
Secondly, the Zone System never "overexposes and underdevelops," nor does it "underexpose and overdevelop." It allows you to find the exposure you need to get the shadow rendering you want. That's part 1, the "exposing for the shadow part."

Part 2 is "developing for the highlights." Some practitioners never get this far, relying on contrast controls in the darkroom or post-processing to get the highlights where they want in the final print.

However, if you want to use the whole system, the highlight will determine your development. Originally, one needed to adjust contrast on the negative itself because there was just one basic contrast of printing paper. Later, there were "grades" of paper in different contrast, but most Zone System users still tailored their negatives for one contrast grade. So, let's pretend we just have one contrast of paper and see what we need to do.

So, for this, you need to know where those highlight values will be after you've determined your exposure for the shadow value. So, basically, you just count stops from wherever you placed your shadow value to where the important highlight reads on the meter. Say you've placed a detailed black in Zone III. You read the highlight, and it's 5 stops higher than your shadow reading. So, if "falls" in Zone VIII. You are sort of finding a "contrast range," but the actual range isn't really that important. What's important is if you want that particular highlight in Zone VIII or not. (All this assumes that you have an idea of what the different Zones look like in the final print; if you don't, the whole system is an exercise in futility).

So, let's say you like that highlight in Zone VIII. Then, you develop "Normally." That's the Zone System "N" development (again, you've already determined, by testing, what "N" development is). Now let's say you really want that highlight in Zone IX; i.e., you need to expand that "contrast range." So, you develop longer to get it there. That's the "N+1" development, which raises the highlight value one Zone. Or, if you really wanted that highlight in Zone VII, then you need to "contract" the contrast range on the negative by shortening development. Yup, that's "N-1."

That's about all there is to it, basically. It can get more complicated with more development schemes (N+2, N-3, etc.,), but the principles are the same.

And, there is all that testing you have to do to arrive at your own personal exposure index (E.I. = personal film speed) and development times. Really, though, refining these is as simple as tweaking things a bit when you're unhappy with the results. If your shadows don't have enough detail, give more exposure (i.e., decrease your E.I.). If your negatives don't have enough contrast, increase your development time (and vice-versa). Underexposure is the bane of black-and-white photography, so err on the side of overexposure.

The above is enough to get anyone started using the Zone System successfully. Refinements can be made later.

Best,

Doremus

 

[pentaxuser]

Doremus I strenuously object to the kind of explanation you give in #19. Enough of those and you could end most of the threads in Photrio within a few posts. Goodness know how quickly you could shut down our "hardy annual" thread of "pre-wet or no prewet"

pentaxuser

 

[Doremus Scudder]

Doremus I strenuously object to the kind of explanation you give in #19. Enough of those and you could end most of the threads in Photrio within a few posts. Goodness know how quickly you could shut down our "hardy annual" thread of "pre-wet or no prewet"

pentaxuser

Uh-oh... I just replied to that one too. Don't be too hard on me...