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Thread: d800, Lightroom, and clipping

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    d800, Lightroom, and clipping

    I ran a little test to see exactly how the d800's dynamic range compares with meter readings, camera histograms, and Lightroom's clip indicators.

    This was not a conventional test by any means, and I looked only at the highlight end of the spectrum. I plan to look at shadows in a systematic way soon, but this is trickier ... subjective results depend on your tolerance for noise, which is going to be dependent on factors that vary from image to image. On the highlight end, either there's detail or there isn't.

    I used an image on my computer screen for a test target. The image is flat gray, with a series of bars along one side that are just a couple of percent lighter than the background.

    Being an old black and white large format guy, I'm using zone system vocabulary, so forgive me if I sound like I'm from the wrong century.

    Calling the camera meter's suggested exposure Zone V (assuming it's aiming for 18% gray), I used this as the base exposure. I then made a series of exposures, each one exposed a stop more than the previous.

    Around Zone Zone 9 (4 stops above base exposure) the histograms indicated clipping. I realize this is just a product of my chosen in-camera jpeg profile (in my case Camera Standard with added sharpening).

    At zone 12 (7 stops above base exposure) lightroom indicated clipping, even with highlights and whites dialed down.

    However, I don't know what this means, because there was no detail discernible in any image above Zone 10 (5 stops above base). Beyond this point, the lighter bars vanish into the background. Lightroom doesn't indicate clipping, and will darken the image below the full white of the screen, but there is no variation between light and dark visible in the image... so at this point we can consider the image to be clipped.

    In summary, at standard settings the camera histogram shows clipping about a stop before actual clipping, but Lightroom (which really should know better) has its own ideas, which have nothing to do with the saturation of the photosite. You will be out of captured detail or tonal variation well before Lightroom warns you.

    The good news is that 5 stops beyond middle gray is excellent for a sensor, and the jpeg histograms give a pretty fair warning, with about a stop of wiggle room.

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    Sr. Administrator Jack's Avatar
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    Re: d800, Lightroom, and clipping

    Just because it all looks the same tone of white (or black) on whatever viewing medium you're using, does not mean that it will *measure* the same. And when we get into very high (or very low) tones, we start to loose the ability to discriminate between them...

    The above is one of the biggest issues with explaining usable DR in contemporary DSLR's versus perceived DR versus the technical DR as read off the sensor.
    Jack
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    "Perfection is not attainable. But if we chase perfection, we can catch excellence."

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    Re: d800, Lightroom, and clipping

    Quote Originally Posted by Jack View Post
    Just because it all looks the same tone of white (or black) on whatever viewing medium you're using, does not mean that it will *measure* the same. And when we get into very high (or very low) tones, we start to loose the ability to discriminate between them...
    It measures the same. In my test there was no possibility of bringing out any contrast at Zone 10 and above (this is a correction from earlier ... I incorrectly remembered that there was recoverable detail in zone 10).

    Playing with the results just now I noticed that even at zone 12 (the highest exposure I tried) it's possible to use the highlight and exposure sliders to bring the values down below "clipping." But there's no information present. At this point the sliders are doing nothing but reducing the luminance of homogenous pixels.

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    Senior Member danielmoore's Avatar
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    Re: d800, Lightroom, and clipping

    Jack, it's high time I said it, your input elevates the merely interesting to the fascinating by both your insight and breadth of knowledge.

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    Sr. Administrator Jack's Avatar
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    Re: d800, Lightroom, and clipping

    Wow, thank you Daniel!
    ~~~

    Paul, I do not use LR at all anymore, but I can tell you that C1 v6 will pull detail out of a zone 10 highlight via the highlight slider if it isn't clipped. Moreover, C1 v6 applies some logic to the pull when the highlight is clipped, rendering a believable result at least some of the time (but admittedly not all of the time).
    Jack
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    Re: d800, Lightroom, and clipping

    Jack, I'd be curious to see if C1 pulls more highlight data off my test file.

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    Re: d800, Lightroom, and clipping

    Paul, I'm just curious which version of LR you're using. Thanks.

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    Re: d800, Lightroom, and clipping

    Quote Originally Posted by Charles Wood View Post
    Paul, I'm just curious which version of LR you're using. Thanks.
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