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UniWB for very lazy people...

Discussion in 'Open Discussion' started by Andym72, Sep 25, 2013.

  1. Andym72

    Andym72 Mu-43 Veteran

    330
    Mar 4, 2013
    Reading, UK
    ... for Oly camera ETTR fans, couldn't you just set one of the Custom WB slots to the colour temp that balances Red and Blue (on the E-M5, for what I've found on the 'net this is at 4800K), and then crank the Green-Magenta adjust all the way to Green? Wouldn't that give near to a unity response in the histogram without all the fiddling about with taking shots of colour swatches on your PC screen with one-touch WB over and over?
     
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  2. m43man

    m43man Mu-43 Veteran

    359
    Aug 28, 2012
    Vancouver
  3. dcassat

    dcassat Mu-43 Veteran

    272
    Nov 16, 2011
    Cloverdale,CA
    I've done the UniWB calibration and I'm going to say no. The calibration of this white balance really does require the multiple steps in refinement to achieve "unity." I think the process is very well documented (at DPR) along with the myriad of issues that I had while troubleshooting the process (you may find my posts outlining my issues there). Don't attempt it unless you have a couple of hours uninterrupted, you will just go crazy!

    It's quite a learning process and is probably worth doing the exercise for that reason. The end result may give you up to 3/4 stop better DR. But you will be viewing everything in green which is a turnoff for many people. I still have the preset but chose to use autoWB instead for composition reasons. Color is pretty important for color compositions in my opinion and overrides any benefit that UniWB provides.
     
  4. m43man

    m43man Mu-43 Veteran

    359
    Aug 28, 2012
    Vancouver
    Color is my work too so I could never imagine messing up preview just to use UniWB, unless there is a OVF like x100 or DSLRs.

    So what Picture mode and Gradation settings did you end up using for the AWB method?
     
  5. dcassat

    dcassat Mu-43 Veteran

    272
    Nov 16, 2011
    Cloverdale,CA
    I have the contrast at +1, everything else at zero. I also have the highlight level set to +7 (gradation). I haven't found changing the highlight or shadow warning level indicators to be helpful but have tried.

    It's very important that you use Rawdigger (free download) to evaluate the exposures you're getting so that you can build your workflow to proper ETTR.

    Rawdigger shows you the real exposure of your images unlike the camera pre-shot,post-shot or Lightroom indicators.

    Let me know if you have other questions, I'll do what I can to help.
     
  6. m43man

    m43man Mu-43 Veteran

    359
    Aug 28, 2012
    Vancouver
    I understand the principles behind using Rawdigger but aren't the values scene-specific? As my subjects are so varied, there would be a large number of tests and workflows I need to build.

    That's why I was thinking maybe a compromise would be using "Picture Mode" with a specific "Gradation" setting that allows me to at least get the blue and green channels right. Using the post-shot histogram, I could ignore the red channel by just making the other channels aren't clipped. This thinking seems to hold up until DPR's report yesterday showing EM1's red channel is much better than EM5, which changes things.

    Perhaps my shortcut of testing and finding a "compromised" Picture Mode would negate the need for using Rawdigger to pre-test multiple scenes and workflows after all?
     
  7. dcassat

    dcassat Mu-43 Veteran

    272
    Nov 16, 2011
    Cloverdale,CA
    I see where you are going, you want to find a way to equalize the color channels in camera so that it "emulates" the benefits of uniwb. For instance you can use a magenta filter to help equalize the channels. But I don't think any camera "mode will get you closer. I think this may be a fruitless pursuit as without uniwb you will always have one channel that is dominate.

    My solution is simply to understand how the clipping point that the camera indicates relates to the actual clipping point of the sensor. I use RAWdigger to make sure that my exposure technique is creating an optimal exposure. And the answer is that the blinkies do a respectable job of showing the clipping point in the highlights MOST of the time. It's not exact and when I doubt it I bracket.

    The bottom line is that the JPG histogram blinkies do not truly represent the Raw data. We'll keep that on the wish list. I want my histogram to be of the RAW image data!

    I consider Gollywop and Anders to be the experts at DPR on this topic, you may send GW a message about your ideas. He has experimented with ETTR even beyond my own work.

    Please share what you learn.

    d
     
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