- But how is this all linked together? Let's say I measure something middle grey, leave it there in zone V, developed the negative. Ok great... But when I put the negative in the enlarger, and I set my time to 10 seconds, or 120 seconds... then the zone V won't be zone V.... So what's the point of placing something is zones if you can then change the print exposure time?
When you expose a certain subject according to what your
reflected light meter says, if you are using a ISO 100 film you are giving it an exposure of H = 0.1 or LogH = -1.
The corresponding density on your negative will depend on how you develop your negative. The corresponding density on your print depend on how you print. The final result linking exposure to print density is the solution of a multi-parameter equation with many different "sets" of resolving values.
If you expose your film according to its ISO rating and insofar as you develop your film according to the manufacturer instruction, you can read on the characteristic curve of the film the density corresponding to the LogH = -1 which is the placement that your light meter gives you.
- Also, if I measure my greycard, how is this even possible to work? If I keep it in the shade it's darker, if I keep it more in the light it's lighter. So the greycard is not middle gray anymore... how does this work then???
Something white appears white because it is very reflective. Let's say 80%.
Something black appears black because it is not very reflective. Let's say 4%.
Something grey appears grey because it is half-way.
"Middle grey" is by standard definition a grey which is 18% reflective.
Now, a black cow and a white cow in the night are all blacks. What differentiates them is their different reflectivity. The white cow reflects more of the light falling upon it.
The 18% card is not "middle grey" because it gives you an absolute "tone" (density) on paper. It's middle grey because it's 18% reflective. A shade of grey cow, not a shade of density on print.
- how the negative knows which zone you place it in, if I place something in zone V, does this has a fixed density value to it? Because zone V can be anywhere right? If zone V has a density of 1.2 and you print long enough to get it back to middle grey... or you can just make zone V look like a zone 8... so, what's the point of measuring in zones if you can change it anyway?
Forget zones please or things become complicated. You don't need "zones" to learn exposure and placing.
Take a characteristic curve of a film. You see D (density) normally on the left, and LogH (decimal log of exposure in lux-seconds) on the bottom.
For a negative film, the curve will be a quasi-straight line giving you increasing density with increasing exposure.
The reflected light measure by your light meter will place the exposure on the graph for ISO 100 where LogH = -1. The corresponding density is on the vertical axis of the graph.
For each added EV of exposure, the corresponding LogH of exposure will be 0.3 on the right. For each EV less of exposure, the corresponding exposure will be 0.3 on the left.
What does "placing" means? When using a reflected light meter, whatever you meter, when using ISO 100, will be exposed at LogH = -1. Whatever you meter. Any shade of colour under any light condition. Black cow, white cow, in bright light, in dim light. If you meter the cow and you follow the light meter, you will put LogH = -1 on film. That's certainly a shade of grey. Which exactly depends on your development and printing procedure. But you are in "grey region".
Now, if you read the light meter and OPEN 1 EV more, you are placing your subject 1 EV "above" that grey. Given the same development and the same print procedure, you will have "placed" your subject 1 EV above "grey". "Light grey" let's call it.
If, instead, you read the light meter reading and you CLOSE 2 EV, you have place your subject 2 EV below that grey.
Let's say that you want to "place" a certain shadow in zone III, i.e. 2 stops below zone V.
You measure that zone.
The light meter tells you: 1/125 @ f/4. That's the exposure that would place that subject in zone V. It would come out grey.
You want to place it in zone III. You close 2 EV, and you expose for 1/125 @ f/8. That will place that subject in zone III. In your 100 ISO film curve, that spot will fall where LogH = -1.6.
- how does the spotmeter know if you go down from zone V to zone III that you will have the lowest available density that can hold texture? I mean, if you overexpose 5 stops, then your shadows are in zone 8.... so, really, any "zone" can be anywhere on the density scale right... it just depends on how you print it and it comes out?
The spot meter doesn' know. By examining the characteristic curve of your film (or of your film - development combination) you decide that you have acceptable texture until, let's say, zone II i.e. until 3 EV below middle grey. So you might choose a certain dark part of your subject where you want texture, and you don't mind if parts of the subjects darker than that lose texture, but that part of the subject, you want it to have good texture. That's the "darkest texture" in your image. You know you can place it in zone II i.e. 3 stops below what your light meter says.
You meter it, note the exposure, CLOSE 3 steps, and take the picture.
I mean... you can fit your zones any way you like, like if I had an Ansel adams negative, which would print perfect on grade 2. If I expose his negative a stop longer.. ok it will look overexposed or high-key but his shadows wont be in zone 3 anymore... What's the correct print exposure then?
this doesn't make any sense
The only way it would make sense to me is that EVERY ZONE has a sort of density on the negative. Which is about the same for every film, depending on the development times. But I cannot seem to find any information about this. So that at a given height, and given print exposure XY would print every density the same. So then it's "linked" to the paper.
Yes. If you maintain equal your development, every zone
in the scene has a fixed place in the characteristic curve of the negative.
The zone system complicates the matter because it teaches you to expand, or contract, the "zones" in the scene in order to have equal, or more, or less "zones" in the negative by using a bespoke development for each image.