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Thread: Densitometer Reading Question

  1. #1

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    Densitometer Reading Question

    After exposing a white card to Zone VIII and developing it, the densitometer gives me a reading of 1.32.

    The clear part of the film reads 0.29

    According to what I read in "The Negative - Ansel Adams" this reading is in the right place for a diffusion enlarger for Zone VIII.

    Question:
    Is the reading of 1.32 the one I use or do I have to subtract the clear film reading 0.29 from 1.32 which would give me the net density and use that one?

  2. #2
    ic-racer's Avatar
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    Re: Densitometer Reading Question

    I always null my densitometer to the film base to minimize the number of mathematic steps.

    If you enlarge/expose some film base to just black on paper (not 'blackest black") then, with the same settings put the Zone VIII negative in the enlarger, and cover half, you should get just off white if negative development was appropriate for your enlarger and paper.

    As you know any exposure variation making the Zone VIII ngative will alter things significantly, so appropriate E.I. determination needs to take place first.

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    Re: Densitometer Reading Question

    Quote Originally Posted by ic-racer View Post

    If you enlarge/expose some film base to just black on paper (not 'blackest black") then, with the same settings put the Zone VIII negative in the enlarger, and cover half, you should get just off white if negative development was appropriate.
    Interesting you would put this because I have just been watching a Fred Picker video where he shows something very similar.

    He mentions exposing the clear film to reach max black on paper and use that time. You mentioned "Just Black". Any reason why not max black

  4. #4
    ic-racer's Avatar
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    Re: Densitometer Reading Question

    In spite of some common teaching, a scientific analysis of 'excellent prints' demonstrated they didnt all reach max black or whitest white.
    I read the Picker book in 1974, i really did not understand film until doing the tests in the book.

    In practical terms doing Picker's test, the paper can really suck up a lot of exposure before revealing its blackest black. This will cause the Zone VIII frame to print too dark and lead to the path of high contrast, overdeveloped negatives that will be difficult to print.

    My experience with students is the tests in the Picker book come out better in a workshop setting with an informed instructor.

  5. #5
    Tin Can's Avatar
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    Re: Densitometer Reading Question

    and I thought we want 35mm film leader to be very opaque

    tested by looking at a light bulb
    Tin Can

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    Re: Densitometer Reading Question

    I can equate to the Z VIII printing to dark which is the reason I am going to do the tests again. You say Just Black which can be subjective of course, I was thinking of doing a series of patches and picking the one just before it maxed out

  7. #7

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    Re: Densitometer Reading Question

    On some films, that unexposed and developed film base can be much denser than you would ever guess.

  8. #8

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    Re: Densitometer Reading Question

    IanB,

    Yes, I would recommend to zero out your densitometer on a piece of developed Zone 0 film before reading for either Zone I or Zone VIII. I use an entire frame or sheet, processed as I normally would, and read from the center area. This will minimize possible erroneous reading due to flare, uneven lighting across the card, etc. After zeroing out your densitometer, a good Zone VIII reading will be in the 1.25 - 1.35 range. Nowadays, I tend to push it into the higher end of that range because I print with cold light and today's VC papers can easily handle it.

    Regarding the max black, what you're looking for is the black patch that looks the same as all the rest following it. You want to view this strip under whatever viewing conditions you use to judge your prints when doing actual printing. Fred advised folks to find what they thought was max black, then back off a step. Why did he say this? Because most folks were using too strong of a light when viewing the strip. What you want is a convincing black, not necessarily the most blackest black unknown to man.

  9. #9
    ic-racer's Avatar
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    Re: Densitometer Reading Question

    Quote Originally Posted by Tin Can View Post
    and I thought we want 35mm film leader to be very opaque

    tested by looking at a light bulb
    i have read every published paper on bw film speed and analysis available from university library end the internet.
    I have not encountered that.
    Could be because film dmax is almost never observed with a 21 step wedge sensitometer exposure of bw negative film.

  10. #10

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    Re: Densitometer Reading Question

    Alan9940
    Thanks for that, I will zero out the densitometer that way. I will also do what you suggested with the max black. I did try it last night without backing up a step but I just felt to my eyes the grey was a little on the dark side for what I would think of Zone VIII so backingup 1 step may just put me in the right area.

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