basing exposure on zone 5 instead of 1

[BetterSense]

The traditional film test has is based on zone 1 density. However, I'm starting to question the wisdom of this approach since I rarely meter off the shadows, and instead use incident light readings. Toe shape can have a large effect on your EI for a given film if you base it on shadow readings. If instead I wanted to do a film speed test for zone 5, what density should I target?

 

[Anon Ymous]

0,7 above fb+f is what is proposed in the zone system theory for zone V, but it's not about a specific density at a specific zone alone. It's about a density range through specific zones.

 

[dpurdy]

The reason people test zone 1 is that it is the threshold of exposure.

 

[ann]

you need to take into account the light source as well, diffusion or condensor enlarger.l

zone V can be from .65 ti .75 for a diffusion head or .60- .70 for condensor.

I have to agree with the above as these numbers are based on a range of densities

 

[dancqu]

Zone 5 Film Density

If instead I wanted to do a film speed test for zone 5,
what density should I target?

There is of course some latitude. I'd think a very minimum
zone 5 density would be 0.5 and maximum of 0.7.

Actually one can not do a film speed test on other than
zone 1. Zone one's 0.1 density establishes the film speed.
Two variables are involved, exposure and development.
In practice one adjusts exposure while holding
development constant. A development of
use should be adopted.

Once one is at or very near zone 1 development may
be adjusted; less will lower while more will lift zone
one. In the same way zone 5 will be lowered or
lifted. Contrast will vary. Dan

 

[BetterSense]

Actually one can not do a film speed test on other than
zone 1. Zone one's 0.1 density establishes the film speed.
Two variables are involved, exposure and development.
In practice one adjusts exposure while holding
development constant.

I understand that increasing development time will increase contrast. I suppose this plays havoc with trying to establish a "film speed" based on a zone 5 density since increasing development will move the zone 5 density up. IF you follow traditional thinking about this, but forget that for a second.

I'm trying to reconcile incident metering, which meters mid-tones, with an idea that negative film's speed is based on the shadows and development can be varied, so the midtones move around on the negative! As you say, it only makes sense to meter the shadows in this case, but the point of incident metering is you just meter the light and let things fall where they may.

The zone system is great because you meter the shadows and figure out exactly how much shadow detail you need and expose just that amount. But with an incident meter you wave it around and get your incident reading and let things fall where they may. But it seems to me that the exposure recommendation is too low if you are just relying on latitude to have adequate shadow detail for the most part. In other words, if you have to subjectively correct the reading the incident meter gives you, depending on how much shadow detail you think you need, well now you are guessing as to the proper exposure again and you might as well be using a spot meter.

If I'm taking a more or less naive incident-light meter reading and letting tones 'fall where they may', why should I not put the meter reading such that my middle grey exposure ends up right into the middle of the curve...with equal latitude below and above...when the negative is developed 'normally' for a normal contrast index? Sure, you'd be exposing 'more than necessary' in flat light, and pay a grain penalty compared to metering off the shadows.

Say you establish a development time so you get .65 contrast or whatever works best, then the zone 5 density won't change, and you can set the film speed right in the middle of the curve. I mean this is what you do when you shoot transparency film...the process is standardized. The development does not change so you just meter the middle and let things fall on the film where they may. How would I go about establishing a development time and zone 5 negative density if I wanted to do this with negative film?

 

[2F/2F]

No densitometer is required. It should be the density that prints to a Zone V print tone with normal printing on your selected paper. You will have to experiment to find out exactly what this is...and use yer eyeballs to decide what Zone V looks like. A grey card can be a decent reference.

The idea is sound if you will be incident metering, but practically speaking, it can be difficult to nail it down this way, as the more exposure the silver gets, the more affected it is by development. As such, changes in development that would not seriously affect the lower tones can have a noticeable affect on the mids. Therefore, you must first make sure that your negative is really developed quite closely to your target gamma before doing your test for EI using Zone V as the determinant tone. There is more room for abnormal development when testing for the lower tones.

So, doing it this way, I would develop for your desired normal amount of contrast first. Then, figure out how to tweak exposure to get that Zone V placement to actually print to a Zone V when you make a print at your normal time and filter.

Remember, the goal is not to find your film's "actual speed". The goal that you are after is simply to find an EI that lets you consistently place your dead mid tone at the scene at Zone V on the print.

 

[BetterSense]

Then, figure out how to tweak exposure to get that Zone V placement to actually print to a Zone V when you make a print at your normal time and filter.

I don't have a "normal printing time", and don't care much. When choosing a contrast to develop to, I would choose it so that normal-contrasted scenes print with a grade 2-3 filter, but that depends on my enlarger. Finding the right exposure seems like it would require plotting a curve so that I can see how much linear range my film has and basically picking the middle.

What I tend to do now is just take an incident meter reading and expose a stop or two more if it's contrasty (preserve shadow detail) and maybe a stop less if it's very uncontrasty. This isn't very scientific though, and I'm wondering why use an incident meter at all and then guess anyway. It seems like I could find an EI where I could just use the incident meter reading and concentrate on shooting.

 

[2F/2F]

I don't have a "normal printing time", and don't care much. When choosing a contrast to develop to, I would choose it so that normal-contrasted scenes print with a grade 2-3 filter, but that depends on my enlarger. Finding the right exposure seems like it would require plotting a curve so that I can see how much linear range my film has and basically picking the middle.

What I tend to do now is just take an incident meter reading and expose a stop or two more if it's contrasty (preserve shadow detail) and maybe a stop less if it's very uncontrasty. This isn't very scientific though, and I'm wondering why use an incident meter at all and then guess anyway. It seems like I could find an EI where I could just use the incident meter reading and concentrate on shooting.

If you don't have a "normal printing time", then you don't have any practically worthwhile way to judge where your tones are falling! You should care about your normal print more than anything else! That is the gold standard for judging your negatives! The basis of good prints are good negatives...therefore what a good negative is must be determined by what a good print is.

The normal print is easy to figure out. Print a piece of unexposed film down bit by bit until you *just* hit the maximum black of your paper.

Then, develop your film until a certain photographed luminance range prints as exactly the same range on the print. Try to shoot a scene that has at least six stops of luminance range, and anything up to 10 stops. When the range of tones at the scene of the exposure perfectly (or close-enough-to-perfectly-to-call-perfectly) matches the range of tones on the print at the normal time and filter, your development is normal for that paper....and it will be different for other papers.

Then, examine to see if what should be Zone V is actually printing to Zone V. If not, make a change to your EI, and run the test again until it does.

...and nobody sez you have to use your normal print parameters to make your actual prints! It is simply a calibration tool, not squeezing your vision into a "normal box".