Question about Developing for the Highlights

calebk said:
Just read that but can't seem to wrap my head round it. I understand exposing for shadows, but the rest of the statement?
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Expose for the shadows so that you capture the detail there on the negative (overexpose).
Develop so that the middle of the contrast of the scene is also in the middle on your negative (by controlling development time).
Agitate to keep the highlight from blowing out (agitate less for very contrasty scenes).
 
braver said:
Expose for the shadows so that you capture the detail there on the negative (overexpose).
Develop so that the middle of the contrast of the scene is also in the middle on your negative (by controlling development time).
Agitate to keep the highlight from blowing out (agitate less for very contrasty scenes).
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Sorry, but I can (and I think should) argue with every single assertion there.

First, exposing to get the detail in the shadows (with negatives) isn't overexposure: it's correct exposure. If your metering tecnique doesn't give you the shadow detail you want, then your metering technique is at fault because it is causing you to underexpose. Negative exposure is keyed to the shadows, but slide exposure (for which most in-camera meters are optimized) is keyed to the highlights and will result in underexposed shadows if the subject has a long tonal range.

Second, only a small part of the characteristic curve is normally used. You can use the lower end and toe, or you can give one stop (or even two) more and use the middle. At three stops you may (or may not) run into the shoulder of the curve. Development time controls contrast, which is why the traditional advice is to develop longer for flat scenes (to get more contrast in the negative) and for less time for contrasty scenes (to get less contrast in the negative). This ensures that you get a full range of tones on middling grades of paper (2 and 3).

With the availability of different paper grades, this is less important than it used to be: contrasty negs require softer grades (1-0-00) and flat negs require harder grades (4 & 5).

Third, agitation is not about stopping the highlights blowing. It's about making sure that enough fresh developer gets where it's needed. Yes, reducing development MAY gve some highlight compensation, with weak developer and very modest agitation, but often, it makes very little difference.

Cheers,

R.
 
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Roger, I must agree with you on every point... Perhaps I tried to simplify too much. I tried to explain "expose for the shadows, develop for the mid-tones, agitate for the highlights" with my very basic approach but perhaps not using the right words.
 
Roger Hicks said:
Finally,meters are NOT (or shouldn't be) calibrated to 18%. This is a Zonie myth. It's about 13%. Read the ANSI/ISO standards.
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Problem for you is that Kodak grey cards are calibrated to 18%. And if the zone system was really doing what it says it is, Zone V would be around 3% (yes three percent) and not 18 or 13 %. But regardless, the difference between 18 and 13 % is so little that it's irrelevant except to people who are so far up themselves over standards that they're sprouting two heads. Less than 1/6th of an EV I think.
 
When I feel ambitious i do a test run with any new film or developer. I assign 4 rolls to the project.
I "tack" up a white towel (kind of fluffy), a black towel (similarly fluffy) and a Kodak Grey card as well as a bright white sheet of paper (an old 2 ply mount board) and a black mount board. Try to pick a place in the shade to avoid excessive contrast.
camera is set up so that all 5 objects roughly fill the frame.
Exposures: 1st shot is at meter reading (aimed at the grey card)
2nd is one stop over
3rd is 2 stops over
4th is 1 stop under
5th is 2 stops under
Rewind the film and do a second roll the same way and then the 3rd roll.
The reason for the rewinding (leave the leader out!!!!!) is that I then will set forth and shoot the rest of the roll(s) in real life shooting - usually a quick walk around the park nearby or just cruise the lanes and streets.
Process roll 1 as per "normal" - either manufacturers information or your previous experience. Roll 2 add 20% time and roll 3 cut time by 20%.

Look at the negative (either scan or with a loupe - or if truly ambitious - some quick prints in the darkroom). The solid black mat-board and the bright white mat-board should hold no real details - just black or clear on the film. The two towels should show some detail in both the white and the black one - and the graycard should be pretty close to the actual card "color"
Once you have shot all three rolls and established at what time/exposure the film behaves like you want it to do. Take the 4th roll and shoot it according to that. Run it through the developer at the established time and if all is well - it should come out pretty close to what you want.
For the 3 test rolls - finishing them off (remember to "blind" wind them for at least 6-7 frames - lens cap on) - try to shoot in as mixed light as possible, bright sun, shadow, even indoor to give you some variables. Be sure to meter all three rolls the same way - or as close to that as is possible. The 4th roll should be used as you usually shoot - with whatever correction to exposure (+1 or -1 exposure or +2 or -2 if that works best)
incorporated.

It is a bit boring to do - but you will soon find out what works and what latitude your metering/exposure works best at.

If you do portraiture - be sure to include some shots in all the test for skin-tones.

Once you have done this - you will have a pretty good idea of how to rate the film and how to develop it. It might take a day to do - but it is well worth it.

Of course, after having done this with various films - I tend to say "To hell with it - and load up with TriX and mix up some D76 for 1:1 for 10 min" - which seems to work reasonably well at iso 320 and Sunny f16.
 
tlitody said:
Problem for you is that Kodak grey cards are calibrated to 18%. And if the zone system was really doing what it says it is, Zone V would be around 3% (yes three percent) and not 18 or 13 %. But regardless, the difference between 18 and 13 % is so little that it's irrelevant except to people who are so far up themselves over standards that they're sprouting two heads. Less than 1/6th of an EV I think.
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I don't think I have a problem, but you may. The relevance of a Kodak grey card to ISO standards is zero: 18% reflectance is a Munsell mid-tone. To be sure, the difference is trivial, so you can get away with reading grey cards, but why are you in favour of propagating myths?

Cheers,

R.
 
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