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Author Topic: WB with Colorchecker Passport  (Read 1489 times)

Mike Guilbault

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WB with Colorchecker Passport
« on: February 18, 2012, 11:42:58 PM »

When creating a custom white balance with the CC Passport, how much of the target needs to fill the frame in the camera?  In other words, do you need to fill the entire frame with the target to get an accurate white balance?  It's a pretty small target and I usually can't fill the frame with my 17-35 so end up having to switch lenses - but is that necessary?
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Mike Guilbault

Schewe

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Re: WB with Colorchecker Passport
« Reply #1 on: February 18, 2012, 11:53:45 PM »

LR 3 or 4? The reason I ask is that a new feature in LR4 is the ability to resize the White Balance tool's target...but generally as long as the WB tool is ONLY seeing pixels from within a specific chip, you should be fine.
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bill t.

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Re: WB with Colorchecker Passport
« Reply #2 on: February 19, 2012, 02:47:52 AM »

If the target is too fuzzy you get an error message to the effect that the software can't find the white L crop marks at the edges of the Macbeth target.  So it's partly dependent on sharpness, the ability to distinguish the crop marks seems to be one the main ways the go/no-go judgement call is made.
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Mike Guilbault

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Re: WB with Colorchecker Passport
« Reply #3 on: February 19, 2012, 10:41:21 AM »

Actually Jeff, I was referring to the shooting of the target with the camera to get a WB Preset, before you even get to LR. Thanks for the head's up of the resizable WB tool in LR4 though - didn't realize that!  I'll have to look for it in my Beta.

Bill, I'm shooting with a D700 and if I have my 17-35 on I can't fill the frame without getting so close that the target gets out of focus.  When I take the preset, the camera comes back and displays "Good", so I'm assuming it is.  I guess if it's TOO out of focus I wouldn't get a Good preset. 

I guess the core of my question is that how much viewfinder do you have to fill with the target to get an accurate WB reading to create an in camera WB preset.  Is it the entire viewfinder, a centre spot, or does it depend on what you have your Meter set too, i.e.. spot metering?
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Mike Guilbault

bill t.

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Re: WB with Colorchecker Passport
« Reply #4 on: February 19, 2012, 02:06:11 PM »

Hold up the card against a green or other single-color background on a sunny day.  Red brick walls come to mind.  Shoot tests with the card at different distances, see where the surrounding color starts to trash the white balance.  Or use on of those little diffuse dome thingies and face the light, maybe even a small sheet of milky plex held over the lens would serve that purpose.
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Mike Guilbault

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Re: WB with Colorchecker Passport
« Reply #5 on: February 19, 2012, 03:04:30 PM »

I was thinking of doing something like that - I was just wondering if someone already knew the answer. Maybe I'll contact someone at X-Rite
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Mike Guilbault
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