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Thread: Histogram and white balance on Phase backs

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    Histogram and white balance on Phase backs

    Two questions! Firstly, the vertical guide lines that segment the histogram on an IQ back are spaced progressively further apart towards the RHS of the screen. Is this to represent the greater levels of information that can be gained in highlights?

    And secondly, on my 5DMkii I could dial in colour temperature (degrees Kelvin) to set white balance, an incredibly useful feature. I find the limited options to set WB well, limiting, on the Phase back. Automatic WB can go all over the place, and setting custom WB is relatively time consuming and still might not allow me to achieve the desired WB - eg, when shooting in shade towards a warmly lit scene. Might a "dial in" function be possible in a firmware upgrade?

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    Re: Histogram and white balance on Phase backs

    I'll add another question regarding the histogram:

    I believe the histogram on my Canon 5DII is generated from the JPG image and not from RAW data (even when shooting in RAW). I just read on a Luminous Landscape tutorial that as a result of how the histogram is generated, we can make the camera create a more accurate histogram rendition of the RAW data captured by going into the image profile being used and turning contrast to a minimum... that this of course will not change the underlying raw data but it will change the histogram.

    My question, then, is does anyone know how the histogram is generated in the IQ series? Is it from the RAW data or from the JPG image, and if from the JPG image, are there tweaks we can make to an in-camera image profile to improve the histogram so it more closely represents the underlying RAW data that was captured?

    Thanks in advance!
    Will

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: Histogram and white balance on Phase backs

    I believe it is generated totally by the Raw in a IQ back. Maybe someone from Phase can confirm this but I never seen a jpg file in any way on a Phase back.
    Photography is all about experimentation and without it you will never learn art.

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    Re: Histogram and white balance on Phase backs

    I too am looking forward to an answer. I use the histogram quite a bit to check for highlight clipping. I'd really like to know if the three channel histograms depict the distributioin of values at the RGB photosites, or if they represent the demosiaced values. If the histogram is based on demosiaced values, then it really isn't as usefull if you like to walk the fine line of pushing your exposure as far as you can without clipping.

    Also, I'm guessing there has to be a jpeg generated at some level to create the preview image on the LCD. I don't think you can actually view a raw image without processing it (demosaic, apply gamma curve, color space and white point).

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