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Thread: Film speed testing

  1. #121
    Chuck P.'s Avatar
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    Re: Film speed testing

    Quote Originally Posted by macandal View Post
    I want to throw this out to anyone reading this. Has anyone done the Ansel Adams film speed testing he recommends in his book "The Negative"? That's the test I'm trying to do here and getting nowhere fast with it. Has anyone done it successfully? Can you share your experiences? Thanks.
    I did this test successfully one time, performing it precisely as instructed in The Negative, no problems for me. Sorry you're having trouble with it.

    But I never performed that method of film testing again because it consumes a lot of chemicals and film for my budget. I'm a big proponent of testing film for each combo that I use, but I want to maximize the film I have for photographing and use the least amount of film for determining EI and "N" development times. That said, you can achieve the same results much quicker here and since you have densitometer, you only need a 21 or 31 step wedge. You'll be able to determine your EI and development times from +2 to -2 with 5 to 8 sheets of film.

  2. #122

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    Re: Film speed testing

    Because there was density above film base, the exposure couldn't have been way off, but as it really didn't change over a stop of exposure, that would indicate the development was insufficient. Of course if could also mean drift with the densitometer. The range of testing exposure needs to be larger. Make it at least 2 stops. And just because the development time was correct doesn't mean something else went wrong.

    I maybe be biased, but this wouldn't be a problem using a step tablet.
    Last edited by Stephen Benskin; 5-Mar-2013 at 10:34.

  3. #123

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    Update on my (troubled) film speed test

    In case there's still anyone out there following my trials and tribulations, and, more importantly, who still cares about what happens, I did the Film Speed Test again and I think this time it worked. This is what happened.

    After trying to figure out what could have gone wrong and arriving at the conclusion (by me) that I had followed all the steps accordingly, I suggested a new set of shots (I think I said this in post #113). These shots would take me one more zone in either direction (it didn't much matter in the lower zone as the previous test had already taken me to zone 0; I went ahead and closed my aperture one full stop more anyway just because I'm obsessive about this sort of thing and I wanted to be damn sure about this). The previous test started at Zone I and stopped at Zones 0 and II. Well, this time I went to Zone III. My shot list and results looked like this:

    My Zone V was f/5.6 @ 1/125. I kept the shutter speed constant (i.e., I didn't change it for any of the shots), only changing the f stop.

    Shot 1: not exposed; just developed (my base) = 0.09 density (d)
    Shot 2: f/22 = 0.1 d = 0.01 net density (nd)
    Shot 3: f/16 2/3 = 0.1 d = 0.01 nd
    Shot 4: f/16 1/3 = 0.11 d = 0.02 nd
    Shot 5: f/16 = 0.12 d = 0.03 nd
    Shot 6: f/11 2/3 = 0.14 d = 0.05 nd
    Shot 7: f/11 1/3 = 0.16 d = 0.07 nd
    Shot 8: f/11 = 0.09 d = 0 nd
    Shot 9: f/22 1/3 = 0.09 d = 0 nd
    Shot 10: f/22 2/3 = 0.09 d = 0 nd
    Shot 11: f/32 = 0.09 d = 0 nd
    Shot 12: f/45 = 0.09 d = 0 nd

    The results I had shot before (shots 1-5 and 9-11) are pretty comparable. Shot 12 was to be expected and so I didn't shoot in thirds of an aperture stop after shot 11 (again, I wanted to be damn sure). As someone pointed out, though, the fun happens in shots 6 and 7, where my density starts going up and gets much closer to 0.1. The head scratcher is shot 8. Why, all of a sudden, did the density go down here? From (shots) 3 to 7, the density was climbing, then, on 8, it dropped. There was nothing different done while shooting this. They were shot in the number I described above, so I expected the number to be higher and therefore, much closer to 0.1. I really don't know what happened there. Maybe shot 7 shows this particular film at its highest density? I don't know. In any case, shot 7 brings me to an ASA of 32. Rounding this number to the closest lower ASA number (if I understood Ansel Adams correctly), this means that with this particular film-lens-film combo, I have to shoot as though it were a 25 ASA film. Is my assumption correct?

    What do you guys think?

    Thanks.
    Last edited by macandal; 19-Apr-2013 at 14:27. Reason: Corrected f stops in shots 3, 4, 6, 7.
    --Mario

  4. #124

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    Re: Film speed testing

    Quote Originally Posted by polyglot View Post
    I would recommend acquiring a copy of Beyond The Zone System by Davis. It lays it all out fairly neatly, though you will need to buy a (not very expensive) step wedge.
    +1
    Don't bother with Adams' method. Davis method is much superior.
    You do not need to test for each lens or each aperture. Film speed is determined by 1. film type and 2. development (developer type, time).
    Cheers!

  5. #125

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    Re: Update on my (troubled) film speed test

    Quote Originally Posted by macandal View Post
    In case there's still anyone out there following my trials and tribulations, and, more importantly, who still cares about what happens, I did the Film Speed Test again and I think this time it worked. This is what happened.

    After trying to figure out what could have gone wrong and arriving at the conclusion (by me) that I had followed all the steps accordingly, I suggested a new set of shots (I think I said this in post #113). These shots would take me one more zone in either direction (it didn't much matter in the lower zone as the previous test had already taken me to zone 0; I went ahead and closed my aperture one full stop more anyway just because I'm obsessive about this sort of thing and I wanted to be damn sure about this). The previous test started at Zone I and stopped at Zones 0 and II. Well, this time I went to Zone III. My shot list and results looked like this:

    My Zone V was f/5.6 @ 1/125. I kept the shutter speed constant (i.e., I didn't change it for any of the shots), only changing the f stop.

    Shot 1: not exposed; just developed (my base) = 0.09 density (d)
    Shot 2: f/22 = 0.1 d = 0.01 net density (nd)
    Shot 3: f/16 2/3 = 0.1 d = 0.01 nd
    Shot 4: f/16 1/3 = 0.11 d = 0.02 nd
    Shot 5: f/16 = 0.12 d = 0.03 nd
    Shot 6: f/11 2/3 = 0.14 d = 0.05 nd
    Shot 7: f/11 1/3 = 0.16 d = 0.07 nd
    Shot 8: f/11 = 0.09 d = 0 nd
    Shot 9: f/22 1/3 = 0.09 d = 0 nd
    Shot 10: f/22 2/3 = 0.09 d = 0 nd
    Shot 11: f/32 = 0.09 d = 0 nd
    Shot 12: f/45 = 0.09 d = 0 nd

    The results I had shot before (shots 1-5 and 9-11) are pretty comparable. Shot 12 was to be expected and so I didn't shoot in thirds of an aperture stop after shot 11 (again, I wanted to be damn sure). As someone pointed out, though, the fun happens in shots 6 and 7, where my density starts going up and gets much closer to 0.1. The head scratcher is shot 8. Why, all of a sudden, did the density go down here? From (shots) 3 to 7, the density was climbing, then, on 8, it dropped. There was nothing different done while shooting this. They were shot in the number I described above, so I expected the number to be higher and therefore, much closer to 0.1. I really don't know what happened there. Maybe shot 7 shows this particular film at its highest density? I don't know. In any case, shot 7 brings me to an ASA of 32. Rounding this number to the closest lower ASA number (if I understood Ansel Adams correctly), this means that with this particular film-lens-film combo, I have to shoot as though it were a 25 ASA film. Is my assumption correct?

    What do you guys think?

    Thanks.
    Hi Mario,

    Exactly what it means. You may proceed under the assumption that your speed is 25 or 32, for 7 minutes in D-76 stock for Arista EDU 100.

    You can see a trend supporting that conclusion. Whether you want to give the extra 1/3 stop based on trend and call it 25 (ignore 8 but believe it would have been 0.1 nd if correctly tested). Or if you want to take 32 as the speed (7 is the closest you had to correct, but since it is a real test result, you know what you would get). Is up to you.

  6. #126

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    Re: Film speed testing

    Maybe you can call it 50 or 64. I am re-thinking how the finding of the 0.1 net density should relate to your chosen EI speed. I may soon recommend making adjustment when you perform a test without flare.

    I believe your camera test was without flare.

    The clearest explanation of the reason you can choose a higher speed than your tests results suggest comes from Ansel Adams himself...

    Francesco Fragomeni shared a video of Ansel Adams, narrated by Beaumont Newhall.

    Listen at 8 minutes, 11 seconds in... "Shadow densities exactly on the right Zone. A little camera flare helped the shadow as expected."

    Early-ansel-adams-footage

  7. #127
    Chuck P.'s Avatar
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    Re: Film speed testing

    Quote Originally Posted by Bill Burk View Post
    Maybe you can call it 50 or 64. I am re-thinking how the finding of the 0.1 net density should relate to your chosen EI speed. I may soon recommend making adjustment when you perform a test without flare.
    The adjustment can also be made on a per exposure basis, using an educated guess as to how much flare may be possible given the subject, I don't like the idea of considering flare to be some mathematical statistical average always to be considered as some constant----I've got too many negatives without any consideration for flare at all that are inarguable in terms of the quality of the exposure and processing and resulting densities-----but! that's not at all to mean that they are equally as good in terms of "art". This is what I do anyway while keeping the EI constant as determined by my own flare-free film test (as found in Schaefer). I'll make a small adjustment with the aperture or shutter (depending) just like you have suggested with assigning a higher EI to adjust for flare, the effect is the same either way, I don't fiddle with the speed rating while in the field. We can't control the subject flare, but we can combat it's effect on the toe of the curve, IMO.

    This is, IMO, what AA did by making such a low shadow placement (Zone I) in the video you referenced. That was a high contrast lighting situation (bright sun with distinct, strong shadows) with the shadows placed on Zone I, with the full intention of flare helping to bring the shadow densities back up to a preferred amount. Did he control flare from the scene, no----but he did control it's impact on the toe of the film curve by intentionally providing less exposure to the shadows than what may normally have been given if flare was not a concern for that exposure. Anyway, that's my take on it.

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