Calibrating 4x5; gray card Zones don't match still life Zones

[Leigh]

Stick with EI 250 for "normal" contrast scenes. ...N-1 EI 200.

A half-stop (25% speed) change in EI yields a full stop change in negative density ? ? ?

How do you consistently achieve a 25% exposure change when the standard tolerance for shutter speed is +/- 30% ? ? ?

These are old shutters, not new computerized exposure controls.

- Leigh

[Bill Burk]

Originally Posted by Andrew O'Neill: "Stick with EI 250 for "normal" contrast scenes. ...N-1 EI 200."

Leigh asked: A half-stop (25% speed) change in EI yields a full stop change in negative density ? ? ?"

I believe Andrew O'Neill is recommending a sliding EI scale. He recommends different EI at different N +/- numbers to try to hold 0.10 density at the speed point for Zone I. The 0.1 speed point normally fluctuates with development time changes.

The "full stop of negative density change" when you specify N+/- whole numbers... occurs at the higher Zones like Zone IX moving down to Zone VIII with N-1...

This kind of film speed adjustment is a common Zone System (or Beyond the Zone System) practice.

(I personally look to "the Delta-X criterion" to justify using one EI for all my development times).

{Richie, sorry I think I stepped outside the scope of "beginning Zone"... I'll try to keep future comments in this thread more relevant to your questions.}

[Leigh]

The 0.1 speed point normally fluctuates with development time changes.

Hi Bill,

Development time has minimal impact on shadow densities (thin areas) of a negative.
It has a large impact on highlight densities (Dmax).

Perhaps the advocates of BTZS have invented new photographic chemistry.

- Leigh

[neil poulsen]

Hi Bill,

Development time has minimal impact on shadow densities (thin areas) of a negative.
It has a large impact on highlight densities (Dmax).

Perhaps the advocates of BTZS have invented new photographic chemistry.

- Leigh

Exactly!

This is what makes the Zone System as practiced by A.A. (et.al.) click. One can expose for the shadows, and then later, choose the developing time for the highlights, without compromising the original decision made for the shadows.

Put another way, regardless of what development time is selected (N-2, N-1, etc.), the shadow areas will stay "pretty much" unaffected. That is, they'll come out "pretty much" as anticipated, when the photographer originally decided on the exposure. (At the time that the photograph was taken.)

There really is an elegance to how this all works out.

[Leigh]

OK.

That's how I've always used it.

"Expose for the shadows, develop for the highlights." (I didn't originate that.)

But that seems to contradict what Bill said:

I believe Andrew O'Neill is recommending a sliding EI scale. He recommends different EI at different N +/- numbers to try to hold 0.10 density at the speed point for Zone I. The 0.1 speed point normally fluctuates with development time changes.

- Leigh

[Doremus Scudder]

Exactly!

This is what makes the Zone System as practiced by A.A. (et.al.) click. One can expose for the shadows, and then later, choose the developing time for the highlights, without compromising the original decision made for the shadows.

Put another way, regardless of what development time is selected (N-2, N-1, etc.), the shadow areas will stay "pretty much" unaffected. That is, they'll come out "pretty much" as anticipated, when the photographer originally decided on the exposure. (At the time that the photograph was taken.)

There really is an elegance to how this all works out.

Well... to a certain extent this works, but as Bill points out (correctly), the Zone System speed point moves around a bit with different development. Film is a bit faster with expansions (N+X) and slower with contractions N-X). The slight overexposure with expansions won't affect printability of a neg much, but you can lose shadows with contractions if you're not careful.

I find I need at least 2/3-stop more exposure when solely using reduced development time for N-2; more compensation for greater contractions. So, if you're planning a larger contraction, be sure to support your shadows by increasing exposure. I have simply memorized exposure compensations for my different development schemes.

Best,

Doremus

[faberryman]

How are you guys getting 1/3 and 2/3 stop exposure changes? On my Schneider lenses, the shutter speeds are at fixed 1 stop intervals, and while the apertures are continuously variable, only full stops are marked. If you get an exposure reading of 1/8 at f18, do you move the aperture lever as smidge past f16? How confident are you about the accuracy of your smidges? Are the shutters on all of you lenses calibrated so you know if they are a 1/3 step over or under (or worse)?

[neil poulsen]

Well... to a certain extent this works . . .

I appreciate the input on this, which I will bear in mind.

As to my own practice, I rarely use N-2, mostly N-1, N, N+1, and once and a while greater expansions. For shadows, I may consider what I can expect for a Zone III area in a scene, but I like to expose for Zone II. Less change in speed that way. (Lower on the toe.) Not entirely sure about the wisdom of this; it's just what I do.

As for testing B&W film speed using the 0.1 fb+f methodology, perhaps one can think of this analogously as lowering color film speed somewhat from that recommended by the manufacturer, so as to make sure that there's sufficient detail in the shadows. This is a common practice in color negative photography.

I've always thought that "0.1" for B&W film was selected as the smallest value that minimizes the exposure needed to, none the less, provide sufficient detail in the shadows. In this regard, shooting B&W film at the mfg. recommended film speed just doesn't cut it. At least, not for me.

[Bill Burk]

{Richie, sorry about adding deeper concepts than you need in your beginners' thread.}

First off, I agree development time has minimal impact on the exposure needed for usable shadow densities of a negative.

The arcane point I am making is that it is a mistake to take your speeds from the 0.1 speed point "all the time". Because the 0.1 speed point moves around a lot. Just look at the little diamonds I drew on the toes of their curves where they cross 0.1... then look up at the associated film speed that you would find... if you always take the 0.1 speed point.



http://beefalobill.com/images/tmxfamily.jpg

[Drew Bedo]

Not a strict Zone guy myself so please accept my remarks with the tolerance you would give to a 5 year old ("yes dear . . .that's nice".)

Bracketing? You are shooting bunch test films, why not shoot several sheets of the scene in thirds of a stop, or whatever interfal you think best? Not only will you get he technical info you are looking for, but some images may be worth printing.

Make sequential exposures on one sheet of film while drawing the slide 1/3 or 1/2 way. ADjust the shutter speed and aperature to get the exposure you want. The development will be identical for each increment of exposure.

A more elegant solution for making two exposures on one piece of film would be a sliding back.

Cheers