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  1. #31
    Steve Smith's Avatar
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    Quote Originally Posted by markbarendt View Post
    I was lucky enough to find and read Dunn & Wakefield's Exposure Manual a while back.
    I bought a copy of that last year.


    Quote Originally Posted by markbarendt View Post
    They actually recommend duplexed incident metering for slides, one traditional reading (mid-tone) is averaged with a light source (highlight) reading.
    And mentioned that in the similar thread we had at the time!!

    Basically, it's using the incident meter at the subject and taking one reading pointing at the camera and one pointing at the light source and going half way between the two.

    This only applies to incident meters with flat diffusers (if I remember correctly) as domed diffusers already take this into account by design.


    Steve.
    Last edited by Steve Smith; 05-02-2012 at 06:48 AM. Click to view previous post history.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  2. #32
    markbarendt's Avatar
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    Yep, exactly Steve.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  3. #33
    RalphLambrecht's Avatar
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    bxxxxxxxxxxb&wfilm is ver orgiving in tems of over exposurebut has little lstitude in terms of under exposure
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  4. #34
    RalphLambrecht's Avatar
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    andre,
    welcome to analog. your method seems very sensible to me!
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  5. #35
    Bill Burk's Avatar
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    fralexis,

    You are getting good, sometimes conflicting advice. Your interpretation of Ralph's charts on post #21... that it is OK to rate at half box speed... is a simple and effective way to assure adequate shadow detail and ease of printing.

    More precise metering can provide you "better" negatives. Better being relative. Less grain (which today is not a common goal of analog photographers). Shorter, or more consistent print exposure times (which can make darkroom work more productive, again not a common goal today).

    I use a 4x5 rangefinder which sometimes requires me to use full rated speed when handheld. But when I shoot landscape, I do not need the highest film speed because I am using a tripod and I love the aesthetic of water at slow shutter speeds.

  6. #36
    andrew.roos's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    andre,
    welcome to analog. your method seems very sensible to me!
    Thanks Ralph!

    And thanks for the very informative illustrations you posted, especially the one showing the same scene photographed with over- and underexposure. It makes the point very effectively.

  7. #37

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    Another way to look at this is that your exposure latitude is a function of two things:

    1) the contrast of the scene you are photographing; and
    2) how many effective contrast grades of paper you have available to you.

    At one end of the spectrum, let's say you are photographing a subject that has both whites and blacks that you want to render realistically, and that the white value is in sun, and the black value is in shade. Let's also assume that you are going to make a contact print, and that you have exactly one grade of paper (#2) and one developer (Dektol).

    In this situation, you have very little latitude for error, either in exposure or development, because you need to render a full tonal scale, and the only tools you have available to you are, ummm... exposure and development. The difference between the low value in shade and the high value in sun is about 8 stops.

    If you underexpose the negative, you'll lose important shadow detail just above pure black, and if you overexpose or overdevelop, you'll blow out your high values, and they'll be rendered without any tone or detail.

    Now let's change the situation. The scene is the same, but it's now overcast, not sunny. The difference between black and white is now only about 5 stops. Furthermore, you're using a variable-contrast paper, and you have filters that get you from grade #0 to grade #5, and everything in between. On top of that, you have both Dektol and Selectol-Soft (or a Beers developer) that can also adjust the contrast grade of the paper you're using.

    In this situation, you have a ton of latitude! Assuming you give the scene enough exposure to get the low values above film-base-plus-fog, you can be off up to three stops in exposure (or the equivalent in over-development), and still get a printable negative. The contrast of your scene is much smaller than your effective contrast grades in printing paper (effective = actual paper grades +/- those attained with soft/hard developers), so you can take your scene's tonal scale, and move it all over the place, or expand and contract it at will.

    I agree with everyone else that, whatever latitude you have, it's on the "high" side. If you underexpose the negative, and there are "low" values in the scene that are important, then you're SOOL. If you overexpose the negative, then it mostly depends on the range of the important values in the scene.

    It's for this reason (and the decline in the ability of modern films and papers to separate the low values in the scene from each other) that Fred Picker, late in his career, changed the way he determined proper exposure. Rather than expose for the low values and develop for the high values, he said "Place the highest important value on Zone VIII, and expose." That exposure placed the low values in the scene as high up on the scale as they could go, and he could then use the other tools at his disposal (mostly paper grades) to place the low values where he wanted them in the print.
    "What drives man to create is the compulsion to, just once in his life, comprehend and record the pure, unadorned, unvarnished truth. Not some of it; all of it."

    - Fred Picker

  8. #38

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    A wrench I'd like to throw in is that development affects the film's effective exposure latitude. For example, when dealing with very high contrast subjects (and this is one of the serious flaws in Barnbaum's book), given a fixed subject brightness range, exposure latitude decreases as development is reduced, due to shouldering effects.

    This runs counter to the way we typically think about development in the context of the zone system. It could be called "zone system failure". The standard zone system formula assumes the shape of the film curve remains essentially constant, and that development modifications shift the curve and/or rotate it. This is valid within a certain density range, but begins to break down when the subject brightness range is long enough to indicate significant or severe contractions.

  9. #39

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    Quote Originally Posted by mingaun View Post
    Ralph, thanks for those images which speaks very clearly.

    Mark
    It iwill be well worth your while to get Ralph's book. Not expensive given the content. In fact probably the best "bang for buck" photographic book in the market place

    pentaxuser

  10. #40
    RalphLambrecht's Avatar
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    thanks, but i'm blushing now. Keep in mindthatsome individual chapters are available as free pdfsfrom my website.othes may be made availble upon request.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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