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Thread: Exposure Target - C1

  1. #1
    Super Duper
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    Exposure Target - C1

    Hi,

    Is there any way to use an exposure target in C1?

    I'm photographing manuscripts and books using a copy set up. Some books fluoresce more than others due to bright pages, some are nearer to the light because they are thicker.

    Is there any way to say photograph a chart with each job then click something on a grey square and adjust the exposure until a readout of values on the square is accurate? I could then do that with every job to make sure that I have exactly the same baseline.

    You can do this with the levels tool if you have a black and white square. Technically. In reality the white square is never white enough neither the black dark enough for accuracy.

    I'd like something where I would establish a benchmark so that even if the lights move slightly or I had a slightly wrong setting or indeed one lens has a different t-stop than another so that the f16 of one is different to the f16 of another, I could use this benchmark to always be able to equalise the exposure to accurate. I need accuracy more than my eyeball can provide.

    This is especially important as shooting an LCC seems to change the exposure drastically and differently each time. I need to be able to get back to accurate using a benchmark.

    Any suggestions?
    I am not a painter, nor an artist. Therefore I can see straight, and that may be my undoing. - Alfred Stieglitz

    Website: http://www.timelessjewishart.com

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    Re: Exposure Target - C1

    my first guess would be to shoot a neutral grey card, then adjust exposure so your histogram bump is centered and keep the exposure constant for each shot, letting the dynamic range of the sensor cover the subject range

    what am i missing?

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    Re: Exposure Target - C1

    It's not accurate enough, I need a to be able to shoot a patch and then bump the exposure until it reaches my benchmark of 200,200,200 or whatever. I can do that in ACR or PS but I can't see a way to do it in C1. I know I can see the RGB values when I pan over an image but don't know how to create a target area by clicking so that the values will stick at the top of the screen as I use the mouse to change the exposure or whatever.
    I am not a painter, nor an artist. Therefore I can see straight, and that may be my undoing. - Alfred Stieglitz

    Website: http://www.timelessjewishart.com

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    Sr. Administrator Jack's Avatar
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    Re: Exposure Target - C1

    Shoot a color checker passport gray ramp, then adjust exposure for the mid or upper quarter mid gray, then tune each end with the levels tool. This will establish the mid/upper-gray, with and black and white points for shot-to-shot uniformity. If you need to further adjust the lower (and/or upper) quarter-tone grays, then I'd use the curves tool.
    Jack
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    Re: Exposure Target - C1

    Yes but adjust to what target? How do I get C1 to give me RGB values other than hovering the mouse over the image?
    I am not a painter, nor an artist. Therefore I can see straight, and that may be my undoing. - Alfred Stieglitz

    Website: http://www.timelessjewishart.com

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    Re: Exposure Target - C1

    From the Phase One Blog:

    Adjustments by Numbers
    2011 February The Image Quality Professor's Blog
    3/4 down the page.

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    Sr. Administrator Jack's Avatar
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    Re: Exposure Target - C1

    To expand on the link above -- to get the flags, click and hold on the dropper tool in the top bar -- after 1 second, all the tool choices open up. Choose the "add color readout" icon and you can place as many as you need by clicking on the appropriate location. If you re-click inside the flag, you can drag and move it; use opt+click to delete it; shift+opt+click to delete all.
    Jack
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    Re: Exposure Target - C1

    More than perfect, thank you, thank you!!!!!!!!!!
    I am not a painter, nor an artist. Therefore I can see straight, and that may be my undoing. - Alfred Stieglitz

    Website: http://www.timelessjewishart.com

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    Re: Exposure Target - C1

    Just tried it out in the studio, couldn't be more happy, has solved a very big problem for me. Really appreciate your help guys!
    I am not a painter, nor an artist. Therefore I can see straight, and that may be my undoing. - Alfred Stieglitz

    Website: http://www.timelessjewishart.com

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