Calibration using 10 zones on a single sheet

[Shilesh Jani]

Hello all,

I am planning on calibrating my film, EI, exposure, development, and scanning process. I want to expose a total of 10 zones on a single sheet. The only way I can think of doing this is to pull out the dark slide (or in my case the paper package of QuickLoad) in 10 discrete steps and make an exposure each time. The exposure at each step will be placed at zone I. So the cumulative exposure for the 1st step will be at zone 10.

Is there any other way of doing this in a single step?

Thank you.

Shilesh

[Donald Miller]

Yep, it is called a Stouffer step wedge.

[Ken Lee]

Find a subject with 10 zones. Or at least find a subject with zone 0, 5, and 9. For zone 5 you can use a standard grey card. If ths sun is bright enough, and the light is especially clear, you can use a sheet of white paper, and for zero, find a shady spot and place a very dark item there. Just measure everything with a good spot meter.

[Roy Harrington]

Hi Shilesh,

The Stouffer stepwedge is a nice way to do it. It tends to be a little tight but I load a piece of film and then the stepwedge in front of it. Then, you have to expose at Zone X or XI.

I used to do the dark slide method though pretty regularly. I found it more convenient because you don't have to keep running back to the darkroom for each test shot. Another thing to consider is that you will be using the shutter and aperture in the ranges that are more realistic. The algorithm is slightly more complicated though since you want an exponential scale for Zone exposure. Expose the whole sheet at Zone I, push the slide in half inch, expose another Zone I, slide in half inch, then expose Zone II, half inch, Zone III, etc. In other words two Zone I's but one of all the others. The idea is that I+I = II, II+II = III, III+III = IV... If you do 3 sheets 1/3 stop apart you get all possible EI's.

Roy

[Darin Cozine]

Here is a step-by-step guide for what to do:

1: (optional) Use a pen to mark a darkslide so you can make 10 evenly spaced exposures. Just under 1/2 inch per zone works best. I use 3/8ths, but you can go up to like 7/16ths i guess. The first mark should completely uncover the film -mark it #1.

2: Select a target which is evenly lit and the same tone. A big grey card works fine, but dont use a small target else you will have to compensate for bellows extention. I used a white foam-core board.

3: Select a normal or longer lens. -Viginetting from a wide-angle lens could tweak the results.

4: Make sure the target is evenly lit. I would suggest against using flash.

5: If possible, select an aperture that allows for -4 to +4 stops.(if metering for zone 5 or if using an ambient meter+grey card) -You dont want to change the shutter speed if possible. Also try to use a medium shutter speed, as those are usually most accurate in older shutters.

6: Move your darkslide to the 1st mark and set your shutter at -4 stops. (or just meter for zone 1) Take the first exposure.

7. Move your darkslide to the 2nd mark AND REPEAT THE SAME EXPOSURE. (the film is now getting 1 + 1 exposure, or zone 2)

8: Move your darkslide to the 3rd mark. NOW open the aperture one stop. Expose the film. (the exposed film is now getting 1 + 1 + 2 exposure, or zone 3)

9: Move your darkslide to the next mark and open the aperture one stop. Repeat until you get to +4 stops. (I know it sounds weird that zone V +4 stops will get zone X, but remember that all the previous exposure give you 1 extra stop. so it is actually "5 +4 +1 = 10"

[Shilesh Jani]

Thank you all. Especially Roy and Darin for pointing out that I+I+I is NOT equal to III.

Regards.

Shilesh

[Kirk Keyes]

The only problem with doing successively additive exposures as Darin suggests is that 10 exposures at 1/10th the time do not always add up to 1 exposure at 1 time.

[Tom Smart]

I ran across this thread when I was going to ask a similar question, to I'll tack it on here. I am planning on doing a similar test, but only want 4 zones on a sheet of 4x5 film: b+f, Zone I, Zone III and Zone VIII. These zones fit the way I use my new spot meter, which is to base the exposure off Zone III (usually), and base the development time off of Zone VIII (if it is indeed 5 steps away, it gets N dev. time).

So I wanted to varify the stops I should use for my personal step wedge. Let's say for instance that f-11 gets me a Zone III. I think I can leave the first part of the sheet blank (for b+f), expose the rest at f-22 (Zone I), push the darkslide in and do f-16 (Zone III), push the slide in and give a final f-5.6 (Zone VIII). Is this accurate?