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Thread: PhaseOne white (un)balance

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    PhaseOne white (un)balance

    Hi there!
    I had the opportunity to test an IQ180 back for five days in April and noted some inconsistency with the automatic white balance, i.e. pictures taken a few seconds apart were yielding significantly different color temperatures.
    The PhaseOne partner here lent me another back, IQ180 as well, today.
    I attach two pictures taken two minutes apart in daylight, WB set on auto. The first picture has a WB of 4,850 and the second one of 2,800. I know the first one is not in focus: took me a few seconds to realize that focus activation had been set to the AEL button ;-)
    I then took some pictures of my wife in my studio, with the lighting coming from ProFoto lights. The inconsistencies are not that significant, but they are clearly visible.

    I know that I can take steps to fix this in Capture One, but I would anyway be interested to know whether other people have met the same issue and whether there is some explanation for this.

    Thank you.

    Attachment 73668

    Attachment 73669

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: PhaseOne white (un)balance

    To be honest I wouldn't compare Phase One auto-WB with something like a Nikon or Canon's abilities. I typically either create a custom WB off a LCC card or X-Rite ColorChecker if I have it with me or generally just leave it set to daylight and change it in C1 Pro.

    This isn't a strong point of the MFDBs really.
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    Re: PhaseOne white (un)balance

    Quote Originally Posted by GrahamWelland View Post

    This isn't a strong point of the MFDBs really.
    I didn't know this. Why is it so hard to implement proper auto WB in a camera?

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    Re: PhaseOne white (un)balance

    I've never trusted Auto WB on any camera, whether with a Phase MFDB or my Canon DSLRs. Auto WB is just too inconsistent.

    I set the camera WB to Daylight, and always am shooting in raw. If possible, I use a WhiBal grey card and take a WB frame that I can use in post in C1 Pro 7. Tweak from there, adjust, and finally output to CS6....

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: PhaseOne white (un)balance

    I always simplistically think of auto-WB as being analogous to reflective light metering vs incident light metering (assuming you are only using the sensor to sample it).

    With off sensor WB only you are looking at the entire scene in the lens, including the dominant colours, and averaging that out to determine a base tone to set the WB. The camera really doesn't know if the object you are looking at is a green tree under daylight or whether it's a yellowish green tree in golden light. It has to guess by neutralizing the colour cast across the averaged image to come up with the WB value. If the contents of the scene change due to you moving the camera etc then it's likely that the averaged scene value will also change and hence WB will be different. That's what you are seeing in the images shown here.

    What you do see with different camera systems is more or less sophistication in calculating the WB value in a frame. (i.e. like matrix metering, it may not be a simple average and also may involve some scene library calculation and manufacturer's proprietary algorithms to pick the best neutral reference).

    Ideally you need some form of secondary ambient light measurement to compare to the captured scene to really set auto WB 'accurately' (whatever that means because you'll probably change it for your creative choice later).
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"
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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: PhaseOne white (un)balance

    Auto means its taking a guess. And that is all it means. You have any subject in front of the camera that is not a perfect grey it will guess at making it grey. Don't ever use it PERIOD. Granted some cams do a fine job of getting it right but its never to be truly trusted. I always either use daylight or tungsten given the output and than use a passport color checker for C1 to balance it perfectly. The problem with auto WB on a back is its on the back and not coming through the camera system like a Nikon or Canon so its always guessing at what color temp to set it at. Daylight it's a fixed 5500 kelvin and will not change its up to you to make the proper adjustments. This is the way it should be too. Frankly they should not even put that setting in there.
    Photography is all about experimentation and without it you will never learn art.

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    Re: PhaseOne white (un)balance

    Quote Originally Posted by Pics2 View Post
    I didn't know this. Why is it so hard to implement proper auto WB in a camera?
    It's not in the camera. It's in the back attached to the camera. The back can only take a guess at the data its receiving.
    Photography is all about experimentation and without it you will never learn art.

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    Re: PhaseOne white (un)balance

    Auto white balance on a P1 back is simply not as good as on a Canon or Nikon.

    I've never used it and never really missed it.
    Doug Peterson , Digital Transitions | Email
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    Re: PhaseOne white (un)balance

    Thank you all for the explanation.
    I have been working with Nikon DSLRs for 15+ years and never thought about the fact that the WB "guesstimate" was from the back rather than the camera...

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    Re: PhaseOne white (un)balance

    Yea and my D800e does a nice job on AWB but you can easily fool it as well.
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Re: PhaseOne white (un)balance

    Well, I have actually never seen anything like that IQ 180 output yesterday ;-)

    This being said, the main learning point for me is that those systems are so different and intended for such different uses that they can't really be compared. But you know that already ;-)

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: PhaseOne white (un)balance

    Exactly and in fact the color and tone is so much better. But don't let the AWB get in your way they are great systems that produce amazing results. One thing I try to tell folks when it comes to MF. It's work and it takes effort and good technique to produce great images and when you nail it , there is nothing like it. I like my D800 e and get very good results but end of day no matter how you slice it MF is just better. I know there are many wars , debates and very very strong opinions on it between 35 and MF. The bottom line is this are you after IQ than MF if your after flexibility than 35. Ideally you have both or at least something to shoot what MF may not the best tool for. IQ 180 is a great back.
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Re: PhaseOne white (un)balance

    I don't mind AWB because I can fix it in ACR. I do value the tint adjustment in AWB and usually I only have to touch color temperature. I am using a Pentax 645D. With my P25+ in the studio, I set WB manually and I am tethered.

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    Re: PhaseOne white (un)balance

    I first tried AWB, but the images always looked terrible, so I switched to daylight. As has been already mentioned, it's a guess with Phase One as I don't believe there is any WB sensor for the back to use at least with a Tech camera. The images I take seem to work better in Capture One with Daylight as the selected WB.

    WB should be more precise on the DSLR as all of them have some form of sensor that actually communicates to the chip and processor, after sensing the ambient light.

    Paul Caldwell

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