2 Unknowns--Exposure & Develpment

Discussion in 'B&W: Film, Paper, Chemistry' started by Tom1956, Aug 18, 2013.

  1. Tom1956

    Tom1956 Inactive

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    OK, got my lensboard made and lens mounted on my 8x10. On Tuesday my Fuji Green X-Ray film comes and I'm off to the races. I've followed a thread on LF Forum, but it is a long thread of mostly back-patting on each other's shots. So I've thought up my own procedure to get a ballpark exp and development. So lets start with straight D-76 in a tray
    I'm thinking find a development starting time first, then move on to finding a film speed. Starting with what I might know as a standard, is that I BELIEVE film speed will be 80-100 range. So, I figure to shoot a fully exposed negative of a big sheet of white paper, with the camera, placing it on Zone 9-10, with a metered film speed of 40. This should give a fully exposed piece of film, but not absurdly exposed, like laying the piece of film on the table with sunlight coming in the window.
    Then, cut that film up, and make progressive developments of the pieces. Not having a densitometer, I figure to use my Luna-Pro pointed at some fairly bright lighting (so as not to overwhelm the meter cell). Then hold each piece of film up to the meter cell until I get to the one that shows no change in the reading. Somewhere between this piece and the piece before it SHOULD be a ballpark development time.
    From that point, begin cutting up more film to 4x5's and use a step procedure till I see detail in Zone 1, or perhaps just shoot a Kodak step wedge till I see a reasonable progression. This should be a base exposure for trial.
    So now I should have a ballpark film speed and development time that I can tweek from there. Opinions? Thank you.
     
  2. MattKing

    MattKing Subscriber

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    Don't use a piece of paper.

    Use something like a white towel - something with texture.

    I'll let others comment on the rest of your procedure.
     
  3. ic-racer

    ic-racer Member

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    Shoot any uniform surface without texture illuminated by light you normally use (ie tungsten vs daylight). Focus lens at infinity. Shoot zone I. Place processed negative over light meter, the frame that drops exposure by 1/3 stop = 0.1 log d = good exposure index.
     
  4. Bill Burk

    Bill Burk Subscriber

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    Do you mean clear & practically clear (then you would be placing the tone on Zone I or II) - or Black and So Black the meter can't tell any more (over 2.0 density - then your plan is fairly reasonable)
     
  5. Tom1956

    Tom1956 Inactive

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    Bill Burk thank you. I do not exactly understand your post. So yes, I meant black and so black the meter can't tell. Is this right? Or are you saying go the other way--no density and first hint?
     
  6. Bill Burk

    Bill Burk Subscriber

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    Ah, then your plan will probably work fine.

    Traditionally tests for speed are done first, the tests for 0.1 density. Because this doesn't change much over a wide range of development times. So I recommend you look for this first.

    When you do the development times tests, keep in mind, your meter probably will be able to accurately measure a dark Zone VIII / Zone IX test negative that is developed the right time.

    Compare the meter reading with nothing... to the meter reading with your dark test negative. The dark negative that the meter tells you is 4 stops darker than nothing will have 4 stops x .3 density per stop = 1.2 density... Which is a reasonable Zone IX target.
     
  7. Tom1956

    Tom1956 Inactive

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    Thanks. I really wanted to standardize my process for Pyrocat HD, which I've never used before. But they want $19.60 just to ship the 12 dollar product. That's 30 some-odd dollars just to get some in the house, and I have to watch every penny. I've got several packages of D-76 lying around, so D-76 it is. Frankly I have an idea I'm going to be fighting an excess contrast situation, but we'll see.
     
  8. Tom1956

    Tom1956 Inactive

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    Thank you ic-racer. Will do it that way. I still like the idea of ball-parking development time first. Then do this. And if a repeat of this process is performed, logically one would have it nailed.
     
  9. Bill Burk

    Bill Burk Subscriber

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    The "problem" with that approach is, to know what exposure Zone IX would be, you kind of have to have an idea what speed the film is...

    And the 0.1 density test results do not change dramatically with development time.
     
  10. Tom1956

    Tom1956 Inactive

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    Thanks, Bill. But this is one of those things I need to start somewhere on guessing a development time. 2 mins? 4?, 10? I need to knock that problem down to at least a vague idea.
     
  11. Bill Burk

    Bill Burk Subscriber

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    Hi Tom1956,

    Yes, most films there are plenty of advice where to start, definitely you want to pick a time around 5-10 minutes - or maybe 15 minutes but I don't know where to start with X-Ray film and the developer you want to use... You could ask that specific question and some people may know...
     
  12. Rick A

    Rick A Subscriber

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  13. ic-racer

    ic-racer Member

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    Like Bill pointed out, always get the exposure index first. Then do the development test.
    Development test is best done in darkroom with your favorite paper and enlarger light source. Project a processed (first guess at development time) Zone VIII negative with your enlarger so the film base is also showing. Adjust enlarger exposure so the film base just prints black with the least exposure possible. Place coin on white area of the printing paper. If you can see outline of the coin, development is correct.
     
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  15. Tom1956

    Tom1956 Inactive

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    It could be that I am thinking along the lines of a misconception, but it has been my observation that the better photographic minds seem to congregate on this site, perhaps with no more providence than a group of tumbleweeds. Still, I find myself bringing thoughts that the other sites have long fruitless threads about, and seem to find better focus here on the final answers.
    All this said, I believe I've conceived a test that will require my having to develop (sacrifice) only 2 full size 8x10 sheets of film and glean everything I need to know on both exposure and development time. Just on the ideas advised in this 14 post thread, my thoughts are in order on the test procedure I will be carrying out this weekend. From that, I fully expect to be able to load up film holders and go out shooting with confidence. To give clue as to the idea I have in mind it to use the T-square and triangle to fabricate alternating "dark slides" to arrange 8 tests on the same sheet, one as exposure test, one as development time test. Actually 3 sheets will be used. The third to shoot the broadside of my house, which is a rural scenic view in itself. In the next 3 months I am going to shoot up 97 pieces of X-Ray film that only cost $29.00 including shipping. Hey, thanks everybody.
     
  16. Tom1956

    Tom1956 Inactive

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    OK I set up and did this test yesterday but the results were inconclusive. Just to be sure I have this straight, I am testing for a film speed bu making 8 exposures between ASA 40 and 160. So I am to meter on my big piece of cardboard for each film speed and close down by 4 stops? Thank you.
     
  17. Bill Burk

    Bill Burk Subscriber

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    Yes exactly. If your results were inconclusive, make bigger differences that will be easier to see: For example you could try EI 3 6 12 25 50 100 200
     
  18. nworth

    nworth Subscriber

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    Development controls contrast. It would be difficult to tell what was proper development by looking at a photograph of a uniform surface. Ideally, you might set up a patchwork of cards which reflected light as Zones 1, 3, 5, 7, and 9 (or, more realistically, 2, 4, 6, and 8). Photograph them a couple of times, cut up the film, and develop as mentioned. That way you could get an idea of speed (from the low value) and contrast at the same time.

    You used to be able to buy packages of reflection gray scale which were ideal for things like this. I don't know if they are still avaliable.
     
    Last edited by a moderator: Aug 25, 2013
  19. jerrybro

    jerrybro Member

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    When I set up my process for 4x5, I placed a Stouffer step wedge in a film holder on top of a sheet of film. I then found a large uniformly lit outside wall, metered the wall, opened up 4 stops, exposed and developed. This one neg helped me home in on my film exposure and development and told me more than any advice I'd read in magazines (what we did before the internet). Eventually I picked up an old densitometer and really calibrated everything. Now I'm coming back after a decade long hiatus and I'm starting all over again with new films, new developers and new papers.
     
  20. Tom1956

    Tom1956 Inactive

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    So which step in the Stouffers' wedge did you use that determined your film speed?
     
  21. Bill Burk

    Bill Burk Subscriber

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    If you plan to use a Stouffer step wedge, then you change the procedure significantly and you open the door to better testing. A step wedge gives better tests than if you do camera tests exposing for Zone I. I personally contact a step wedge to light in a sensitometer, which is basically a box that aims a flash at the strip.

    On your original plan of tests for Zone I, one of the sheets would have hopefully measured close to a density of 0.10 and the EI speed you shot that film at is what you would consider your tested speed.

    When you use a Stouffer step wedge, depending on the one you buy, the difference between steps is 1/3 or 1/2 stop each. So hopefully, when you exposed a step wedge, one of the steps of your developed film measures close to density 0.10 - You can count the steps to arrive at how many f/stops of light are blocked (you can do that in your head)... Or you can do some math using the known density of that step to account for how much light was blocked by that step.
     
  22. Tom1956

    Tom1956 Inactive

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    I only have a McBeth reflection densitometer, made in probably the early 80's, of unknown calibration. So I guess it's back to the Zone 1 method. So far it is evident already that this Fuji HR-T green is much lower than the ASA 80 as described by a few guys in the LF forum. Seems I need to move my test range a good bit lower.
     
  23. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    Please keep in mind that HRT is not panchromatic film and it's green sensitive. The film is not sensitive to warm colors like oranges and reds. So red objects that have a high luminescence might show up as black on your film. You can make this an advantage by processing Fuji HRT under a safelight and process by eye. I've done some test and with HRT and I've rated my film at ASA 200 with XTOL. Also the film has no anti-halation backing and there's an emulsion on both sides. The emulsion gets really soft and best processed in hangers or with flat bottom trays.
     
  24. Tom1956

    Tom1956 Inactive

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    Man, that's wild, According to the zone 1 test I just did, I'm getting a film speed of 25, maybe a hair faster--40 tops. That is with D-76 1:3 6 minutes at 70-72 degrees. I wonder why there's such a big difference? You say 200, some on the LF Form say 160, a lot more say 80, and I'm getting 25. Very strange. But I've already tried shooting an actual photo at 80 and it was underexposed bad. I'm asking around to friends for a computer mouse I can cut up and make a shutter tester out of, but my shutter SEEMS pretty close already. That's the only variable I can think of. My meter is dead on the money. It's a Luna-Pro that I put a 1.35 volt voltage regulator in, and it is in line with my 2 SBC's and my Sekonic.
     
  25. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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  26. Bill Burk

    Bill Burk Subscriber

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    OK. If it were standard film and developer, I'd be able to help more...

    Did you use a "Tungsten" light source? That might be way slower than daylight if I put 2 and 2 together right about red sensitivity (because Tungsten bulbs are "sort of" on the reddish yellowish side of the spectrum).

    Next, I'd seriously develop longer. This could account for less speed than expected. Maybe you'll eventually find your time should be 10 to 16 minutes.

    And finally since you kind of estimated the speed at 25 - use that as your Exposure Index to base your calculations for the high "Zones" exposures.