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  1. #1

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    Determining Base Exposure

    How do you determine the base exposure of a print? In other words, how do you go about choosing which element or elements of the print to base your exposure on?

    How do you distinguish between a high value that should be the basis of the base exposure, and a high value that needs to be burned in? If the "high value" is not the basis for the primary print exposure, then what is?

    I was reading "The Art of Photography", by Bruce Barnbaum, and it was like the blinders had been lifted from my eyes.

    I've never really enjoyed printing, mostly because, well, I'm not very good at it. Many of my prints are too dark, muddy and lifeless, and now I think I know why.

    I've been basing my print exposure on values that need to be burned in!

    Barnbaum gives the example of a landscape that has two dominant areas. One is a washed-out sky, and the other is a foreground of land that is deep in shadow.

    If you base your exposure on the proper aperture/time for the sky, then adjust the contrast of the paper to retain detail in the foreground, you wind up with a perfectly balanced, perfectly muddy, perfectly awful print! You got off on the wrong foot, and nothing you do from that point on is going to rescue the print from being awful.

    What you needed to do was recognize that the print has two parts, both of which are low in contrast. If you try to solve the problem of the great disparity in range of tone between the sky and the foreground by using a low-contrast paper, it exacerbates the problem of the already-low contrast in each of the two parts of your print.

    What you need to do is treat the photograph as having two separate parts: the bright sky, and the dark land. Instead of switching to a low-contrast paper, you might actually use a higher-than-normal-contrast paper, to separate the tones in each part, then burn in the sky and dodge the land.

    I used this thinking process today in printing a scene with a bright beech tree, surrounded by leaves that are of various tones between Zone IV and Zone VI. The difference in tone between the lightest and darkest leaf is already small. If I base the exposure on that necessary to print tone in the bright tree trunk, I'll have to use a #1 or #0 filter, which will further compress the tonal range in the leaves, and I'll wind up with my usual muddy, lousy print.

    So instead, I based the exposure on the lightest of the leaves, and burned in the tree trunk. Eureka! <sigh>

    Thoughts?
    "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

  2. #2

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    Inexperienced printers tend to pull prints too soon and wind up with muddy or mottled looking prints.
    Last edited by Gerald C Koch; 07-26-2012 at 12:45 AM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  3. #3

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    Well, my thoughts are that Barnbaum's book is lousy. But if it's working for you, I can't really argue. Glad to hear you are starting to enjoy printing. People don't focus nearly as much on printing as they should.

  4. #4
    markbarendt's Avatar
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    What I have found for my own printing is similar, the toughest part is picking what to peg.

    Various subjects and sensibilities take various approaches, my norm is for pegging bright skin tones first, sans skin or a reference frame with a target, blacks are first; highlights are normally addressed as an after thought.
    Mark Barendt, Beaverton, OR

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

  5. #5
    Blighty's Avatar
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    I always ensure that the filtration and exposure are correct for the subject not the scene. Sometimes this is the difficult part - just deciding where you want the eye to rest. The burning in and dodging needed then (hopefully) becomes apparent.
    Norman is an island.Time and tide wait for Norman.

  6. #6
    Mike Wilde's Avatar
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    I use the form of Ralph L's test print rig from 'way beyond monochrome'. Mine lets you expose 7 identical parts of the image to yield 7 1x5" sections exposed 1/3 of a stop apart. The rig lets you slide a piece of 5x7 paper 1" over each time to expose a section of 1x5" window cut out of the overmask.

    I use the information from this test print on a quite small enlargement - like a 5" high print, to see where the bulk of the image looks best. This time becomes my base expsoure. I cheat a bit and integrate analyse to pick a time that will rrint well to be in the middle of the sequence. It only saves me from making a second more centred test strip.

    So now I have a base exposure time.

    I then look either way on the test swatches to see what areas look better with a bit less exposure. These become my dodge areas.
    Then I look to which areas look better with more exposure. These ares become my burn areas.

    If the dodge or burn area is too unruly to do by hand, it might be the starting point where I will consider making a contrast reducing unsharp mask.
    my real name, imagine that.

  7. #7
    David Allen's Avatar
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    The starting point for any print is to know the minimum time to achieve maximum black - assuming that your image has such a tone.

    When I print, I always determine an exposure/grade that gives me dark (but with details) shadows at the known maximum black time and which delivers a good separation for the mid-tones. Any remaining overly bright highlights I then burn in at a lower grade (typically Grade 2).

    To achieve this requires a couple of hours of boring tests to determine your personal EI, the minimum exposure required to achieve a maximum black and knowing where to peg the darkest shadows where you wish to retain detail.

    The key to achieving consistently good negatives is the correct placement of your shadows when exposing the film and ascertaining the correct development time for achieving good separation without losing the highlights. A simple and relatively quick way to way to pin all this down for the future is to do the following (WARNING: reading these instructions is more time consuming and a lot more laborious than actually doing it!!):

    1. Find a scene with with a good range of tones

    2. Using the box speed, meter the darkest area in which you wish to retain shadow detail

    3. Move the camera so that you are only photographing this shadow area

    4. From the meter's reading close down the aperture by 2 stops or increase the shutter speed by two stops and then expose 6 frames at: the given exposure then +1 stop, +2 stops, -1 stop, -2 stops and -3 stops less than the meter has indicated

    5. Process the film

    6. Using the frame that was exposed at -3 stops less than the meter indicated (which should be practically clear but will have received lens flair, lens and developer fogging - i.e a real world maximum black rather than an exposed piece of film edge that has processing fog but not received any light as would a real part of the negative) and do a test strip to find out what is the minimum exposure to achieve maximum black - Print must be fully dry before assessing this.

    7. Do another test strip with the first exposure being what you have selected for achieving maximum black minus your dry-down compensation then plus 1 second, 2 seconds, etc

    8. The time that achieves full black inclusive of compensation for dry-down is you minimum exposure to achieve maximum black for all future printing sessions - print must be fully dry before assessing

    9 You now know the minimum time to achieve full black inclusive of exposure reduction to accommodate dry-down

    10. Using this minimum exposure to achieve maximum black exposure time, expose all of the other test frames.

    11. The test print that has good shadow detail indicates with an exposure that will render good shadow detail and achieve maximum black provides you with your personal EI for the tested film/developer combination

    12 If the negative exposed at the meter reading gives good shadows, your EI is (when metering shadows where you wish to retain good detail) the box speed (i.e. for 400 film you need to set your meter at 400)

    13. If the negative exposed at +1 stop more than the meter reading gives good shadows, your EI is (when metering shadows where you wish to retain good detail) 1/2 the box speed (i.e. for 400 film you need to set your meter at 200).

    14. If the negative exposed at +2 stops more than the meter reading gives good shadows, you EI is (when metering shadows where you wish to retain good detail) 1/4 box speed (i.e. for 400 film you need to set your meter at 100).

    15. If the negative exposed at -1 stop less than the meter reading gives good shadows, you EI is (when metering shadows where you wish to retain good detail) double the box speed (i.e. for 400 film you need to set your meter at 800).

    16. If the negative exposed at -2 stop less than the meter reading gives good shadows, you EI is (when metering shadows where you wish to retain good detail) 4x the box speed (i.e. for 400 film you need to set your meter at 1600).

    You have now fixed your personal EI but there is one more testing stage to go.

    1. Find a scene with with a good range of tones

    2. Using your EI, meter the brightest area in which you wish to retain highlight detail

    3. Move the camera so that you are only photographing this highlight area

    4. From the meter's reading open up the aperture by 3 stops or decrease the shutter speed by three stops

    5. Expose the whole roll at this setting

    6. In the darkroom, process one third of the film for recommended development time

    7. When dry put negative in the enlarger and make a three section test strip exposing for half the minimum black time established earlier, for the established minimum black time and for double the minimum black time.

    8. Process print and dry it.

    9. If the section of the test strip exposed for 1/2 the minimum black time gives bright highlights with a trace of detail then the film requires a minimum of 20% more development

    10. If the section of the test strip exposed for the minimum black time gives bright highlights with a trace of detail then the film is correctly developed

    11. If the section of the test strip exposed for double the minimum black time gives bright highlights with a trace of detail then the film requires a minimum of 20% less development

    12. You can use the rest of the exposed highlight test film to fine tune the development time.

    YES - it is VERY VERY boring but . . .for the investment of minimal materials and a few of hours you will have pinned down all of the key variables that it is really worth doing.

    Back in the real world, all you then need to do in future is meter the shadows that you wish to retain good detail with meter set at your EI and then stop down the aperture 2 stops or increase the shutter speed by 2 stops. In the darkroom start your first test print with the minimum exposure to achieve maximum black (inclusive of dry-down compensation) and go from there (meaning this will give a tonally very good print but your vision for the scene might be for more/less contrast, brighter/darker mid-tones, etc).

    Best,

    David
    www.dsallen.de



 

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