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Thread: E-510 Gradation Settings Compared

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    Default E-510 Gradation Settings Compared

    The next photo I post to my blog is going to be of a grey card -- aside from the dogs, I've photographed nothing else for the past three days.


    I've taken a series of photos of my exposure target to gauge the camera's idea of a neutral grey and how the Gradation setting affects its output. The setup used the 50f2 at f/4.0 so that vignetting is non-existent, manually thrown out of focus so that surface irregularities won't affect the results, a custom white balance and a tripod. I'm blessed with very consistent light intensity.

    I shot in RAW+JPEG to determine if any of the changes affect the raw data. When the images were being reviewed on my computer, I used Photoshop Elements to view the jpegs, and Lightroom with all settings zero'ed to view the raw captures. I used Apple's Digital Colour Meter utility to take readings from the images to ensure that the results from one piece of Adobe's software was comparable to the results from another piece of Adobe's software.

    I'm someone who always reads the conclusion first, so here it is: The gradation settings affect how the camera meters a scene, as well as changing the jpeg engine's settings.

    When set to "High Key", the camera will over-expose by 1/3 to 2/3 of a stop. (my note: the test data below shows 1/3, but using the camera typically produces a 2/3 stop change.) When the gradation is set to "Low Key" the camera will under-expose by 1/3 of a stop. Keep the light and subject consistent, and in Aperture or Shutter priority modes, change only the gradation settings. At f/4, I was moving from 1/80 to 1/125 to 1/160. For raw data, this is exactly the same as dialing in exposure compensation, but it does not show up as such in the EXIF data.

    The changes in the jpeg engine are a little harder to evaluate from a single-tone target. I can't say how it will affect the contrast and response curves, but I can see that it's changing the value of middle grey by more than the shift in exposure. You can see this especially in the second set of test photos, where I used fully manual controls: the raw exposure is identical but the middle grey of the jpegs changes value. I leave testing this in the real world to others, as it's beyond my qualifications.

    Note that you can't forget about the gradation settings when you're capturing raw data in manual mode: the camera's meter will still tell you that you are over or under compared to its 'normal' setting. If you prefer your cameras' metering to me more conservative this could be worth looking into.



    I haven't included any of the sample photos, but I can provide them if anyone really wants me to. Here's the bare data:

    The gradation settings affect how the camera interprets mid-tones and biases the exposure. Shot in Av mode at F/4.0 and iso100:

    JPEG:
    Tv Value 8bit / percentage
    High 1/80 160 / 62.5%
    Normal 1/100 118 / 46.5%
    Low 1/160 85 / 33.5%

    RAW:
    Tv Value 8bit / percentage
    High 1/80 103 / 39.5%
    Normal 1/100 88 / 33.5%
    Low 1/160 73 / 29.5%

    Next I ran the same three shots but in Manual mode, 1/125, F/4.0, iso100:

    JPEG:
    Value 8bit / percentage Meter Indication
    High 109 / 43% -0.7
    Normal 106 / 41.5% 0
    Low 95 / 37.5% +0.3

    RAW:
    Value 8bit / percentage Meter Indication
    High 81 / 31% -0.7
    Normal 81 / 31% 0
    Low 81 / 31% +0.3


    ...note that the 8-bit values and the percentage values may not always match. I've had to do some rounding, and all three channels didn't always agree exactly. This is still just one person's test of a single camera; your camera may differ from mine and my methods may be flawed. Enjoy them for what they're worth.

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    Default Re: E-510 Gradation Settings Compared

    Confirms what Phil came up with on the E410
    http://www.dpreview.com/reviews/OlympusE410/page17.asp

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    Default Re: E-510 Gradation Settings Compared

    Hi Matthew,

    I'm just curious - how did you process the RAW files in Lightroom? As far as I know, Lightroom doesn't read the ORF files from the E-510 yet.
    Jim
    E-5, E-30, E-330 IR, 12-60mm, 50mm Macro, 70-300mm, 9-18mm, 40-150mm, FL-50R
    My Smugmug Site

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    Default Re: E-510 Gradation Settings Compared

    Download the ACR 4.1 update that includes the DNG converter, and run it through that. Then the DNG can be imported as usual.

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    Default Re: E-510 Gradation Settings Compared

    I thought that was the case. I wish the 1.1 Lightroom update would become available soon!
    Jim
    E-5, E-30, E-330 IR, 12-60mm, 50mm Macro, 70-300mm, 9-18mm, 40-150mm, FL-50R
    My Smugmug Site

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    Default Re: E-510 Gradation Settings Compared

    Hi matthew,

    Just my two cents.

    JPEG:
    Tv Value 8bit / percentage
    High 1/80 160 … –1.51 +0.95 stops
    Normal 1/100 118 … –2.46
    Low 1/160 85 … –3.46 –1 stops

    Next I ran the same three shots but in Manual mode, 1/125, F/4.0, iso100:
    JPEG:
    Value 8bit / percentage Meter Indication
    High 109 … –2.71 +0.08 stops
    Normal 106 … –2.79
    Low 95 … –3.13 –0.34 stops


    Luminance measurements are needless, and what is more, interpretation of them requires knowledge of exact shape of the tone curves.

    If assume that 1/100 is the reference exposure. i.e., 0 stops, then 1/80 / 1/100 = 100 / 80 = 1.25 and for the high key: log2 (1.25) = +0.32 ≈ +1/3 of stop, and for the low key: log2 (100 / 160) = –0.68 ≈ –2/3 of stop. Therefore:

    High 1/80 +0.32 stops
    Normal 1/100 0 stops
    Low 1/160 –0.68 stops

    Also remember that the sRGB or aRGB numbers (code values) are distorted and 224 isn’t two times more than 112. After backward transformation to linear sRGB for example, we can find: 224 corresponds to –0.42 stops or 0.7474 (74.7%), and 112 to –2.63 stops or 0.1615 (16.2%). Of course, 255 corresponds to 0 stop or 100%.

    From this it follows that 224 is 4.63 times more (2.21 stops) than 112 in the sRGB space. As well, 112 (–2.63 stops) is 4.08 times more (2.03 stops) than 56 (–4.66 stops).

    Have in view please, Phil Askey doesn’t know these fundamentals and his tone curves and other graphs look falsely.

    Added black and red numbers show the luminance and luminance differences respectively in relation to 118 (upper JPEG) and 106 (lower JPEG). Of course, we cannot interpret these differences.


    Best regards
    Alex

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