A Simplified Zone System Calculator Table

Click to access zone_system_table-2.pdf

This is a simple zone system table I developed after working to learn the zone system a dozen years ago. Please feel free to use it or share it with attribution. I find it quite a lot simpler and faster than any formulas or logging techniques. It is a PDF set up to print as a 3X5 card or to be loaded onto your mobile phone for quick field calculations.

Simple instructions are on the card, but here’s how you use it:

  1. From the scene in front of your camera, previsualize the area of full shadow detail (zone III) and of full highlight detail (zone VII). These aren’t true black or true white, but the areas that should show some detail in the final image.
  2. Meter the area for zone III first, and find on the table the row where that aperture lands under zone III. Shutter speeds do not appear on the table, so set the shutter speed that pairs with your selected aperture in this reading and leave it.
  3. Meter for zone VII next. Looking down the same row where your chosen aperture was for zone III, find the aperture listed in the zone VII column.
  4. Set your aperture to expose for the aperture in the zone V column from that same row. You now have your exposure.
  5. In that same row, find the aperture you metered for zone VII. Look at the top of the column for the development N number.
  6. Develop according to that N number above your zone VII aperture.

An example:

You arrive at a scene and pull out your spot meter. You meter for the shadow that you would like to hold just a little bit of detail in the final print. That reading is 1/125 sec. @ f/5.6. Set your shutter to 1/125 and then look in the zone III column of the table for 5.6. See it? Sixth row down.

Next, meter the highlight where you’d like just some readable detail in that print. Meter also for 1/125. It reads f/32.

On that same row, look in the pink zone V column. It says f/11. That’s your exposure aperture. Set the camera to 1/125 @ f/11.

Look at the table one last time. Finding that VII reading (f/32) look to the top of the column where f/32 sits. It says N-1. That’s your development factor for that exposure. Scribble it on your film holder, in a notebook, on the roll itself, or on a memo on your phone. You might find your own process for using the table, too. For example, I have come to quickly read for zone III, jump to the zone V entry on the same row, set and shoot, then circle back to meter zone VII and find the development factor.

I don’t have a densitometer and never dialed in my materials the way maestro Ansel did. I use Chris Johnson’s basic development factors to adjust development times for most film/dev combos:

Standard films      T-grain films
N-1        0.7           0.9
N-2        0.6           0.8
N+1       1.4           1.1
N+2       2              1.2

If the results are not perfect, they are at least very good. My negatives all land nicely in the range of very small and easy printing adjustments, particularly with the flexibility of variable contrast papers. Frequently I land a perfect grade 2 negative.

Creative Commons License
This table is licensed for your use under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

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