Nine Zones With One Click of the Shutter

Discussion in 'Exposure Discussion' started by dancqu, Mar 3, 2005.

  1. dancqu

    dancqu Member

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    Is there any way to do that? Is there any target
    made for that purpose? I'd like to take up less
    than nine frames of film. Dan
     
  2. Jorge

    Jorge Inactive

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    Stouffer step wedges....
     
  3. dancqu

    dancqu Member

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    That won't do. I've in mind a white to gray
    target perhaps two by three feet. Nine stops may
    be more than possible. I may play with some paint.
    Even five stops would be helpfull. Dan
     
  4. mikewhi

    mikewhi Member

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    With 4x5, I get 6 zones per sheet. If you shoot this, I can tell you how I do it. I don't shoot step wedges. Making a target with 5 or 9 patches exactly 1 stop apart will be a pain. You might try putting a Zone V negative in the enlarger and making 4"x4" exposures, each one stop apart and see how something like that works.

    -Mike
     
  5. smieglitz

    smieglitz Subscriber

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    Try the grayscale patches in a Kodak Professional Photoguide or pick up their reflective gray scale target ("control patches"?).
     
  6. Lee L

    Lee L Member

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    Dan,

    Jorge's suggestion is a bit brief, and he's assuming you'll intuit how to use the wedge. You don't say why this won't work for you, so I'll assume you don't understand one possible use of the wedge and jump in with that. Forgive me if you know this already. There's not enough information in the thread for me to determine whether you're aware of this way of using the wedge.

    You don't have to shoot the Stouffer wedges at 1:1 through the lens. You can use a transmission wedge, put it on top of the film in the holder, then expose in camera to an evenly lit uniform target with the camera focused at infinity, but at 5 stops more exposure than your meter reads for that target. I use a plastic diffusion disk over the lens for even illumination. This 5 stop increase over the meter reading puts the "middle gray" of the step wedge at the right level of exposure, and the other levels "fall" into place. You're basically making a contact print of the Stouffer wedge in camera. You can get 1/2 stop or 1/3 stop increment wedges.

    You can then contact or projection print the resulting negative on whatever material you use for display to calibrate from start to finish.

    Lee
     
  7. Bruce Osgood

    Bruce Osgood Membership Council Council

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    I understand "Place and Fall" but would metering a gray card and shooting at that exposure be different than your opening up 5 stops?
     
  8. Lee L

    Lee L Member

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    Bruce,

    The Stouffer wedges are 10 stops in increments of 1/2 or 1/3 stops. Think of it as putting a stepped neutral density filter over the film inside the camera. You have to overexpose 5 stops from the "flat field" you're metering outside the camera in order for the middle of the neutral density range on the step wedge to produce a medium gray on the film. If you just shot at the metered reading, you'd end up with the thinnest density in the step wedge registering slightly above medium gray, and the denser sections of the wedge would all fall below "Zone V". Opening up 5 stops from the meter reading (which doesn't account for the neutral density in the wedge in contact with the film) puts the middle of the Stouffer scale on Zone V, so you get the full range of the step wedge on film, or at least what part of that range the film/developer can handle.

    Lee
     
  9. BarrieB

    BarrieB Member

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    Not owning a 'Step-Wedge' having adjusted the exp. by 5 stops I assume that if this was done on several sheets of film one could then test various Developers / time combinations !!!!
    Could you use this method to obtain ' Personal Film Speed ' ?
     
  10. Bruce Osgood

    Bruce Osgood Membership Council Council

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    " Stouffer scale on Zone V" .....I got it now. Makes sense.

    Thanks
     
  11. rbarker

    rbarker Member

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    Another option might be to incrementally pull the dark slide to pre-marked spots, essentially making a "test strip" on one sheet of film through multiple exposures of a white wall. I haven't tried this, so I can't attest to its usefulness, but it should work. The cumulative total exposure should place the wall at the desired zone (VIII or IX), if my thinking is correct. The strip at the right Zone V density should tell you the speed, and multiple sheets could be used to zero in on "N" development.
     
  12. Lee L

    Lee L Member

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    See noiseoil's article: http://www.apug.org/forums/article.php?a=104 for a writeup on testing for film speed and development changes with a Stouffer wedge. He uses the 1/2 stop per step model.

    Incrementally pulling a dark slide could do the same job, but it would be hard to crowd as many steps as the Stouffer has in two rows into a single row. The Stouffer wedge is just a labor and materials saver. I figure it also keeps me from making the human error that creeps into making so many multiple exposures on one sheet, pulling the dark slide in increments... Did I slide the slide after cocking and shooting strip 13 and 14? But it could certainly be done that way by a careful worker.

    Lee
     
  13. smieglitz

    smieglitz Subscriber

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    The problem with doing the darkslide method revolves around the number of exposures that must be made as well as the fact that shutter errors will be multiplied and an intermittency effect occurs. (A series of cumulative exposures does not equal the effect of an instantaneous exposure which should be otherwise equivalent.)

    To do the darkslide method it is probably easier to do two sheets: one using a zone I exposure (= 1 unit of exposure) as the unit and a second sheet based on a zone V exposure (= 16 units of exposure). What you want to achieve is a series of stripes representing zones 0 through zone X or in other words, a series of stripes each one stop/zone apart with the following units of exposure in the sequence: 0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512.

    To get this the darkslide is withdrawn almost all the way so that only a bit of the film is covered. This will give the film-base +fog or zone 0 density. The film is exposed to a zone I exposure (-4 stops from the indicated meter reading) and the darkslide is inserted a little further. The film is given a second zone I exposure to bring the uncovered film up to a cumulative exposure equal to zone II. (You would now have zones 0, I & II represented if the film was developed at this point.) The darkslide is inserted a bit more and the zone I exposure is repeated TWICE (to get an area of cumulative zone III). The darkslide is inserted a bit more and the zone I exposure repeated FOUR times (to get up to zone IV). The series of exposures on this sheet now goes from zone 0 through zone IV or 0 through 8 units of exposure.

    The method is repeated on the second sheet except now the film is exposed using zone V (the indicated meter reading) as the unit. This will result in zones V through X on the film or exposures representing 16, 32, 64, 128, 256 & 512 units on the second sheet.

    A simpler way to do the test on sheet film is using the Stouffer wedge placed above the film inside the holder and giving an exposure equal to zone X. This gets all the densities on the film at once and eliminates the multiple exposure and intermittency effects.

    A third way to do this involves using 5 darkslides with holes punched in different locations. The film holder is loaded as usual with a standard darkslide in place. Once in the camera, that darkslide is withdrawn and replaced with one of the darkslides having a small hole punched through it. An exposure is made for zone I and then the darkslide is flipped and an exposure is made for zone II. That darkslide is then replaced with another having the hole somewhere else and a zone III exposure is given. The darkslide is flipped, zone IV exposure given, darkslide replaced with another, zone V exposure given, darkslide flipped, zone VI exposure given... until the zone X exposure has been made. The regular darkslide is then replaced so the holder can be removed from the camera and the film processed. The result of such a test can be seen in the example image which I hope will be found below. This is a test I did using an HP5+ sheet and testing for a van dyke brown print emulsion exposure. (Note that a Stouffer wedge has been placed on the film when making the contact sheet to help calibrate the print emulsion response. It is not part of the zone test described above.)

    Joe
     

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  14. dancqu

    dancqu Member

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    Well, that takes care of it in one frame - one click! But it
    won't do in my case; a 6 x 4.5 and two 6 x 7s.

    I have tested 9 zones with 10 frames; 2 zone 5s at aperature
    change. The 9 are nice to have and I've a splendid Tobias TB+
    which will read any and all zones it sees. All I really need are 5
    zones. It is zones 3, 4, 5, 6, and 7 that make a print. Zones
    2 and 8 can be guestimated. Zone 1, while a speed point
    for most, prints black, and zone 9 white.

    I think I'll make that trip to the paint store. A five zone
    2 x 2 foot should be easy enough. I'd like to remove any
    vignetting and even development issues by shooting
    center of frame. Dan
     
  15. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Try Gordon Hutchings' Zone board, described in _The Book of Pyro_.

    The basic technique is this--You make a long board with a lamp in a reflector on top aimed down the board (you could also just use a lamp or a light on a light stand and an evenly colored wall). The intensity of the light will fall off proportionally to the inverse square of the distance, so place the dark end on Zone I and label it, say with a large Post-It note and a marker. Then use a spot meter to see where Zone II falls and label that, and then Zone III, etc. Photograph the board, and the labels will tell you where to take your densitometer readings from.
     
  16. Lee L

    Lee L Member

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    OK. I have a better idea what you're up against now, and I appreciate the wish to get away from lens falloff.

    First, you could try a Kodak Q-13, reflection step wedge and color control patches that smieglitz mentioned. The gray scale there is 20 steps in 0.10 density increments between 0.0 and 1.90, but it's smaller than you want.

    Second, I too have thought about using paint color samples and countertop laminate samples for DIY step wedges. The laminate has the advantage of performing well in the field. I actually picked up samples of both about 2 weeks ago, but haven't had time to calibrate them. I have some laminates that would do well, but I'm sure you can pick some out at your local store. The most neutral set of paint samples I found locally was the Behr brand at the local Home Depot, series 780E for the lighter patches and 780F for the darker patches. These come with four dark grays and three light grays on two cards that are 5" x 6", and would make a decent target. Estimating visually from the Kodak Q-13 scale, they appear to be about the followng reflection densities: 0.0, .05, .1, .3, .5, .8, and one about 1.3 or 1.4. You could also find a darker black I'm sure.

    You used to see larger samples of some laminates that would make a good larger target, about 5" x 6" each, but I haven't seen those lately. My local Home Depot doesn't carry laminate samples in any size anymore, but Lowes has a good selection of small ones.

    The Hutchings Zone Board sounds good too. I haven't read the book. I'll have to calculate some practical dimensions for that.

    Hope this helps.

    Lee
     
  17. dancqu

    dancqu Member

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    Why not a pint of flat white and flat black.
    I may even 'print' five maybe 7 zones. I think
    my Sekonic L-228 analog good to .03; not bad
    for calibration.

    Black paint; I've read of 2.08. Probably nothing
    very special. Dan
     
  18. Lee L

    Lee L Member

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    Flat white and flat black paint would work well. Some places do a custom computer match to an existing color, so you could take in a gray card and try to get a matching pint of that as well for a three zone setup. I have no idea how close they could come to an exact match.

    There are sheets of felt in craft shops sized 9x12 or so. A white, black, and a gray or two might work for a larger target. How about high brightness office paper, a gray card, and some black felt for a three zone target? You could use multiple pieces of each for a larger target. How about a few pieces of appropriately chosen matt board? These options would make a nice larger target. The possibilities are pretty much endless if you don't need calibration to exact values.

    Has anyone tried half-tone style scales produced on a laser printer? With certain computer graphics programs, you could produce your own custom scale. Print a bunch of different densities and measure, then make a scale that works for you. For a large target, you could do full sheets of single tones and put them together on a backer board.

    Lots of ways to get there.

    Lee
     
  19. dancqu

    dancqu Member

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    No, no. Mix the paint. A really good white and black may
    be zones 1 and 9 or close. The five middle zones would need
    to be mixed. I think 7 zones possible.

    The linearity of my Sekonic L-228 may be a problem. Do you
    know of any way to check a light meter's linearity? Dan
     
  20. darinwc

    darinwc Subscriber

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    I wouldnt think that any reflective surface would provide enough difference to cover more than 2 or 3 zones. Remember that in a photography setting, you are trying to capture areas that are brightly lit verses shaded.
     
  21. Lee L

    Lee L Member

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    The standard gray scale patches on a MacBeth Color Checker cover reflection densities from 0.05 to 1.50, which is 4.8+ stops. I'm not quite sure what you mean by zones in this context, but if you mean stops, you can certainly get a broader range than 2 or 3 stops with common materials all in the same incident light.

    Lee
     
  22. Kirk Keyes

    Kirk Keyes Member

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    I visited Alan Ross last year, and he had a large black box mounted on his window, so I asked what it was. He opened it up and it had a 3x3 (I think, maybe 3x4) grid of Wratten ND filters mounted against the window. Each grid was a one stop difference. The other side of the box had an opening to place the camera lens into so it can shoot the grid. He had an additional side opening so he could meter off the grid before making an exposure.

    He commented on how expensive it would be to make one of these today due to the cost of Wratten filters, but I think it could be done quite a bit cheaper with Lee or Rosco theatrical filters. The grids were something like 3 or 4 inches square, and you could buy a sheet each of 1, 2, and 3 stop ND theatrical filters and just cut them up and sandwich the filters. Total cost for the filters should be about $25.

    If you do this, make sure you set the focus for the lens at infinity. The grid will be out of focus, but the samples he showed me were not too blurred that you couldn't make good densitometer readings.