BTZS + Modern Incident Meter w/ Digital Readout

[Mark Barendt]

Rick I'm not trying to advocate for one system or the other here, just for understanding what they do.

Yes, the incident meter assumes that "the light it's in" integrates or averages out to middle gray, but like you also said "systems don't make decisions, photographers do". Regardless of the metering method we use, we have to ask ourselves "what am I measuring" and factor that in to find what we might consider a normal camera setting. From there we have to decide if we want it to render normal or high or low.

BTZS users factor in what they are measuring when a shaded reading is taken as the basis for setting the camera exposure. That concept is also used when they find the difference between their shadow and highlight measurements to help them decide on their EI and processing.

Dunn uses that concept when Duplexing, which he did with a flat face incident meter.

With regard to different skin tones and spot metering those faces, as long as the placement offset to a "normal" camera setting is "a known" it doesn't matter what the specific tone is, this is a true zone system concept and equal in practice to incident metering. With an incident meter we don't need "a known" target (skin tone or whatever else) in the scene to find the same camera setting.

[Mark Barendt]

incident metering doesn't give you the tools to plunge a puddle into black Zone 0 for an abstract. (Maybe it does but that's the point I think Rick is making).

I agree, spot metering can tie a specific tone to a specific point on the film curve, incident metering can only infer that relationship, but with a little experience it can infer that very well.

[Bill Burk]

With regard to different skin tones and spot metering those faces, as long as the placement offset to a "normal" camera setting is "a known" it doesn't matter what the specific tone is, this is a true zone system concept and equal in practice to incident metering. With an incident meter we don't need "a known" target (skin tone or whatever else) in the scene to find the same camera setting.

And in this sense, reading off your palm and opening one stop is the ultimate incident meter.

And also, Minor White invented BTZS. His "Zone System Manual, How to Previsualize Your Pictures" outlines "Short Cut Exposure-Development Calculations"

1. Take a meter reading off the palm in shadow
2. Place on Zone IV to set exposure
3. Take a meter reading off palm in sun
4. Development determined by difference in the two readings.
5-Zone difference N-2
4-Zone difference N-1
3-Zone difference N
2-Zone difference N+1

[rdenney]

I know little about BTZS, but my issue is with the justification for using an incident meter. It seems that the justification is to be easier, but using it shaded, aimed at the light source, then with a flat diffuser, and so on, is at least as fiddly as using a spot meter to measure several parts of the scene.

Given that an incident meter is not measuring directly what the film sees, I can't see how it could be more accurate, though even Sunny 16 works in the hands of a skilled user, so I'm sure it could be as accurate. To be as accurate, though, it seems to me we have to apply subject-specific effects that would be explicitly measured using a spot meter.

I have no complaint with whatever BTZS might do to recognize that development for different contrast affects zone placement, in terms of density, etc. That seems a separate issue, and for that discussion, I listen only.

Rick "who, by the way, owns a very nice incident meter for controlled lighting" Denney

[Bill Burk]

...everything I've read about BTZS suggests that it is a superset of ZS methodology, not a replacement for it. ...Phil Davis' book describes the Zone System not in passing, but as a core component. The third edition contains several photos that are described as having been made with the Zone System, and numerous diagrams which show the correlation between BTZS and Zone System terminology. He points out the strengths and weaknesses of both systems..

Then I oversimplify when I categorize BTZS as an incident metering only system.

I am still fascinated by Minor White's "Short Cut Exposure-Development Calculations" - as it sets the stage for what Phil Davis codified in BTZS.

[Bill Burk]

...about BTSZ, but my issue is with the justification for using an incident meter. ...

My issue with it too, however as Ken points out, the actual BTZS reference book and software contains and supports Zone System technique.

[Ken Lee]

According to Wikipedia:

In mathematics, especially in set theory, a set A is a subset of a set B, or equivalently B is a superset of A, if A is "contained" inside B. A and B may coincide. The relationship of one set being a subset of another is called inclusion or sometimes containment.

BTZS includes the Zone System, not the other way around. The same may be said of Sensitometry in general: it contains BTZS, but not the other way around.

[Bill Burk]

BTZS includes the Zone System.

I think we're saying the same thing.

I admit I'm wrong to take issue with "BTZS" when I only take issue with "BTZS - Incident Metering". I'll try to be more clear when I say things like "When I read BTZS - Incident Metering, I couldn't figure out how to create stylized renditions so I decided to stick with Spotmetering."

[jcoldslabs]

Does embarking on this detailed of a procedure at the outset to determine proper exposure only pay off if your shutter speeds and aperture settings are accurate to within 1/3 stop and if you develop for precisely the prescribed amount of time at precisely the level of agitation with precisely the same dilution of developer every time? Any process is only as accurate as the sloppiest link in the chain, and it would be a shame to lose some of the attempted metering precision because of a faulty darkroom thermometer. Or are there equally rigorous processing procedures proscribed by BTZS?

As much as I appreciate those who can wrap their minds around the BTZS methods (I cannot), I know the other steps in my processing will never be as accurate and therefore I don't worry about it. None of my old shutters is CLA'd or calibrated, for instance, so exposing with pinpoint accuracy will never be possible no matter how well I meter a scene. Sort of like having pristine vinyl records, a $3,000 turntable, a $5,000 amplifier and $100 speakers. But my hat's off to those of you with the smarts and the motivation to both understand and practice the methods outlined in this thread. I feel a bit like I do when I read about quantum mechanics: it is fascinating, but my small brain does not have the power to fully grasp it.

Jonathan

[Bill Burk]

Does embarking on this detailed of a procedure at the outset to determine proper exposure only pay off ...

For me it's like a game of darts. Just hitting the board is a good thing. If you keep hitting low it helps to aim up a bit.