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Thread: zone system target?

  1. #1
    Resident Heretic Bruce Watson's Avatar
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    zone system target?

    I do enough testing (EI, normal development) that I'm bored by it. I go through five or six sheets of film each time. PITA. I'm getting ready to do it again (Acros in Acutol). I'm thinking there has to be a way to make this easier, less painful, and more accurate.

    What I'm thinking is, I need a zone system target to shoot. Maybe about 1.5x1.2 meters (5x4 feet). It would have, say, eight patches on it varying in reflectivity representing zone I through zone VIII. What the heck, make the patches for zone I and zone VIII bigger than the rest and separate them into 1/3 zone increments -- zone 0+2/3, zone I, and zone I+1/3 -- zone VII+2/3, zone VIII, zone VIII+1/3.

    Put that on the wall, light it evenly, and expose and process one sheet of film. Use a densitometer to identify where (.1 + filmbase + fog) occurs on this film. If it's in the zone I patch, you're done. If it's in either the zone 0+2/3 or zone I+1/3, you are also done because you can adjust your EI accordingly and not have to retest. Once you find your EI, you can immediately read the zone VIII patch and decide how to adjust your normal development time. Again, having the 1/3 increments would help you estimate your time adjustment.

    This just seems like it would save time, and save film/processing. But I can't be the first person to ever have thought of this. There must be a reason people don't do it. Enlightenment, one way or the other, appreciated as always.

    Bruce Watson

  2. #2
    おせわに なります! Andrew O'Neill's Avatar
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    zone system target?

    Why don't you try making a zone board as outlined in Gordon Hutchings', Book of Pyro? You get a piece of wood about 10 or 12 inches wide by about 6 or 8 feet long. Paint it flat middle gray. Cut out little squares of paper and write on each of them zone numbers from 0 to X. Clip them along the edge of the board. Inside a dark room stand the board up or hang it vertically. Point a spot light down on it. I use a 500 watt daylight bulb I picked up for a few dollars (Canadian 'cause I live here, eh!). I control intensity with a dimmer switch. With your spot metre (hope you have one!) take a reading from the zone X patch which is up on the top of the board. Now point your metre down a bit until you get a reading that is exactly one stop less than the zone X. Place the zone IX there. Continue on down the board. I've been using this method for years now. You only need maximum of 5 sheets of film but you can get by with 4. You get all zones on one sheet of film. When you are ready to test your film, take a reading from zone III patch, place that reading on zone III. Expose one sheet and develop it. If you have a densitometre you can check if your zone I is right and carry on from there. When you are ready expose 4 more sheets all at the same exposure and develop all for different times. This is a very easy way to in camera film tests. I leave my zone board in my darkroom when I want to do a quick test. I double check all the zones with my light metre just to make sure there was no change before I make exposures. Hope this helps and that I made sense.

  3. #3
    Moderator Ralph Barker's Avatar
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    zone system target?

    It would seem to me, Hogarth, that if you can get the target patches to represent the steps accurately, it should work nicely. The large size of the target should get around the bellows-extension issue of using smaller targets like the 2"x14" Kodak B&W step wedge. I suspect the reason most people use a blank wall and multiple sheets may be the convenience of not having to make or store a target of appropriate size.

  4. #4

    zone system target?

    I do something kind of similar (though not as precise) as you're suggesting, an idea I got from a profesor. On my cambo with a rotating back, I cut a piece of black matt board to fit inside the rear standard, and cut a square out of one corner that was just under 1/4 the size of the board. I put the piece of board in the rear standard behind the back, at a given EI make one exposure at zone 1, turn the back 90 degrees, make another at Zone V, turn it expose for Zone VIII, then do this is 1/3'rd stop steps from 1/3 faster than the rated speed, to 2/3 stops slower, leaving me with 4 sheets to process which is a more realistic scenario than is processing one sheet at a time. Then take each neg, figure out which one has the speed I want, and I have a rough idea of how the film curve is shaped, how my development is. Then if I want to plot the whole curve (from zone 0-X), I can do so with 3 sheets of film. Hopefully that gives others some ideas anyway.

    Peter

  5. #5

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    zone system target?

    George DeWolfe described this approach in View Camera mag quite a few years ago. Patches of mounting board with one stop reflectance difference; 4 patches glued on the fifth larger board. Works very well, I have used this method for years, gets you in the right ball park quickley, do fine tuning in the field.

  6. #6

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    zone system target?

    This is, indeed, a viable method. I've been doing it for years.

    The squares only have to be large enough to read with your spot meter. The trick is arriving at accurate densities. I was able to get them to within a few tenths in the darkroom and closer with an airbrush. It's a bit of a project but well worth the investment. You can find a complete account of my "Abbreviated Zone System" here:

    http://www.wehmancamera.com/tecban.html

  7. #7

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    zone system target?

    Another quick way is to expose a sheet of film in contact with a Stouffer 21-step (or 31 step) wedge in your camera while pointing at an evenly lit white surface (texture not required). Expose the negative using a zone X exposure at the manufacturers recommended speed. Develop, and either read the patches with a densitometer, or eyeball it. If the 3rd lightest patch is 0.1 over fb+f, then your film speed is correct. For each step to the right, knock a 1/2 stop off your film speed. For each step to the left, add 1/2 stop. In this case, a 31 step wedge would probably be better than a 21 step wedge, but it's accurate enough.

    To determine if the contrast of the negative is correct, you should make an enlarged print, and try to get the value V patch to match a gray card, or something you know is 'round about value V. If the value VIII patch is just off pure-white, then your contrast is correct. Too white, decrease development time; too gray, increase development.

    Later, rinse, repeat, until you've got it nailed. Then, using your new EI and develoment times, expose 4 more negatives and use shorter/longer development times to determine N-2/N-1/N+1/N+2 development times.

    Ideally, it should take about 6 negatives to get a pretty good idea of what your correct EI is, and what your N+/- times are.

  8. #8

    zone system target?

    Edmund optics has a number of test targets.

    http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=1329

    But I was thinking it would be real easy to just an inkjet to print 8 or more large squares and paste them to a foam core board.

  9. #9

    zone system target?

    Hogarth,

    I know exactly how you feel because I am about to recalibrate using new films and lenses. I use a method that I found in a book called How To Use The Zone System For Fine B&W Photography by John P. Schaefer, HPBooks. The book is out of print but you could probably find it on half.com or amazon.com, etc. The procedure does, however, require a separate exposure for each zone but you can do many tests on a single sheet of film.

    To do it, you get an old film holder and about a dozen spare slides. You could, of course, buy new slides for a holder you already have, but I found a pile of old holders that I used. You will have to modify slides so that you cannot use them for photography. I found that to be no problem.

    Now, you drill a hole in each slide but in a different location. I have three rows of holes with four holes in each row for a total of 12 holes. I would have to dig them out to see, but I think I drilled holes about 3/8" or so. You can easily fit even more holes.

    Now, you put the loaded holder in the camera (this slide has no hole, of course). Then remove the "good" slide, replace it with your first "holed" slide and make your first exposure. If this is your film speed test, just repeat adding (or subtracting) 1/3 stop for each successive exposure. (I generally just change the EI on my spotmeter and place the exposure on Zone I but whatever works for you is fine, of course.)

    When developed, I just look for the closest (equal to or over) .10 d.u. over b+f to determine my film speed.... just standard procedure.

    Then you use the same slides to do your development tests. Each sheet of film will have at least 12 exposures on it. I'm talking 4x5" film here - you can get many more on larger film, of course. If you are shooting a larger format (say 8x10) and you have a reducing back, you can still use 4x5" film for the test to save money on film. So, with a single sheet of film, you can plot the curve for a specific development time or method.

    This probably all sounds more complicated that it really is. If anyone is really interested, I could scan pictures and text from the book and send it to them. The book actually had some good ideas but the author almost literally walked in Ansel's footsteps to take pictures he used for examples. In some cases, he literally put his tripod in Ansel's tripod holes! Irritating, but the book is still quite useful.

    That said, I really like the idea of getting all exposure tests on a single sheet with one exposure. That would eliminate potential errors be much less tedious. I know someone who had a grid of ND filter material that he placed on a light table and exposed all at once. He described it to me but I didn't actually see it myself so don't know the exact setup. If you did this, of course, you would have to figure in your bellows factor which is no problem.

    I do remember reading Hutching's method in his book (which I have) but I forgot all about it. It sounds promising. With any artificially lit tests, I would make sure that the EI is the same for that film under that type of light before doing the test. I find, for example, my films to be less sensitive to tungsten lighting.

    Great question. And very timely for me.

    Best

  10. #10

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    zone system target?

    All good ideas. My suggestion is, whichever method you select, test that Acros in Perceptol 1:3. You would probably like the results very much.

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