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Old August 16th, 2006, 03:20 PM   #1
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HVX White Balance made simple

Since posting the HVX color sample clip I've had a lot emails asking about what white balance settings I used or, what the best method is for getting proper WB setup.

First, a little background into what White Balance is:

The human eye doesn't compensate for changes in color tempurature, your brain does. When you move from outdoors to indoors your iris adjusts for the amount of light but your brain tricks you into thinking colors are the same. You actually have to learn to "see" color, which was one of the first things had to learn when shooting 35mm film, was to un-train my brain. You can actually see how yellow/red tungsten light is vs how blue things look in bright overhead cloudless sun (skylight) once you stop allowing your brain to make those adjustments for you - what us old-school film guys called "BCB" (brain color-blindness).

If you wanted your camera to see color just as your eyes do then the simple thing to do is never use any other color space than 5600k - that's what your eyes are "balanced" for. That's why most print and slide films are "daylight" balanced for 5600k, and color correction comes in the form of filters - or Photoshop. But, that's obviously not practical since indoors things get ruddy and fluorescents get green.

There's really 2 ways you can set WB in the HVX:

1) Most are using the traditional method of putting a WB card in front of the camera and using the AUTO WB set button and let the camera determine the proper setting. This can cause inconsistent results depending on exactly what kind of light is hitting the WB card. For example: if your target is getting bright sun but you incorrectly hold the card and the camera sees shade then the subject will go blue, and vice-a-versa.

The other con to use the AWB button is that it can over-compensate when you don't want it to, say for example during sunsets. In the Color Sample Clip I posted you'll notice the sunset colors were really vibrant, even before custom color settings were applied. If I had used the AWB button during those segments the colors would have been much flatter and muted.

2) The second method is much simpler and takes the sometimes problematic issues of capturing the proper light on the WB card. The HVX has 2 built-in presets for WB which covers 90% of what you might shoot: 3200K (tungsten) for most studio work (this doesn't apply if you're using the newer studio fluorescent type lights) and 5600k for all outdoor/bright sun work. So the simple method is thus:

A - Put the WB switch on the side to PRESET
B - Tap the AWB button on the front; this toggles between 3200k and 5600k in the camera. Once set you can fine-tune the WB manually:
C - Goto the SCENE FILE menu and use the COLOR TEMP setting which will shift between bluer (minus settings) and redder (plus settings).

Once you eyeball a perfect color response with manual temp settings (if need be), you're done. Never use ATW (auto tracking white) unless you're in an ENG or documentary situation where the WB is constantly changing and you want the camera in AUTO exposure mode.

Note: If you're in a primarily fluorescent or mixed lighting situation you can still use the simplified method and fine tune to compensate or, just use the AWB button and white card to compensate.

With regard to how I shoot, I always shoot location work with the 5600k preset and manually tweak to compensate for skylight or overcast conditions, epsecially with skin tone and studio is always at 3200k and so far I haven't needed to tweak temp for studio work.

If you shoot with D-SLR's you can use this same simple technique for WB; either manually dial-in 5600k or, use the bright sun preset which is the same. Studio strobes and on-camera flashes are also balanced for 5600k.
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Last edited by Robert Lane; August 16th, 2006 at 03:51 PM.
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Old August 16th, 2006, 04:40 PM   #2
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Wow Robert, nice info, helped me a lot! Thank you!

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Old August 16th, 2006, 04:49 PM   #3
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Robert,

I've just purchased an 82mm 85 filter (actually got an 85B) for exterior work because I was told that at pre-set 5600 the HVX is balancing by pushing the red gain higher and thus increasing noise.
I believe Barry said something about this months ago.
I'm actually following up my clients request on a camera rental.
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Old August 16th, 2006, 06:53 PM   #4
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Quote:
Originally Posted by Leonard Levy
Robert,

I've just purchased an 82mm 85 filter (actually got an 85B) for exterior work because I was told that at pre-set 5600 the HVX is balancing by pushing the red gain higher and thus increasing noise.
I believe Barry said something about this months ago.
I'm actually following up my clients request on a camera rental.
I hadn't heard that before so I haven't tested for that, but considering there is always noise in the HVX signal it probably just becomes more visible when reds are accented.

I wouldn't recommend using any color corrective filters on any digi-body, video or still other than ND or circular polarizer. You'll lose a bit of light with CC filters and it really makes CC in post much harder and makes fine-tuning WB in the camera a little more difficult too. The reason is that the filter is a fixed amount of color and can't be changed; you may find that the 85B is either too much or too little compensation and will have to compensate again with in-camera settings. Then you're making 2 different kinds of correction which is really going to make getting good color more challenging.

If using the screw-on filter is a more comfortable workflow or gives you satisfactory results then by all means do it, but I wouldn't recommend it. Your best bet is making in-camera WB corrections as good as you can and then using post techniques to finish the job.
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Old August 16th, 2006, 08:31 PM   #5
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Robert,
I would keep in mind though that on all professional 2/3" cameras, Daylight balancing is accomplished through a filter wheel with an 85 or 85ND filters.
Old Ikegami's used to give you a switch for electronic 85 equivilents but it was generally avoided for the same reason mentioned above - elevated reds and noise. Only used it in very low light like at magic hour, when you needed the stop.

On the HVX the ND switches appear to be physical filters ( i'm not totally sure though) but the 5600 adjustment is certainly electronic so I would think a physical filter would be preferable.
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Old August 16th, 2006, 10:09 PM   #6
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What about the Black Balance?

I was testing different WB settings this weekend. I assume, of course, that I first had to set my proper exposure and THEN set my WB. Using a plain sheet of paper, I was careful to not have any shadows casting on it, but I found that the angle was important as sometimes a glare (though one not visible to my eye) seemed too bright for the camera. I tested on a bright clear day over the course of a few hours. Frankly I didn't notice any difference between my custom set and the 5600k preset - a good thing I guess.

My question is, if I find a custom setting I like do I have to reset it even if I toggle through different frame rates. Do I have to reset WB if I go from P2 to tape? Also the manual says to reset the black balance when you first get the camera. I've been setting White Balance AND Black Balance every time I go out. Is this inadvisable?
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Old August 16th, 2006, 10:14 PM   #7
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Good question Brian. To my knowledge setting BB is only required once but Barry can probably answer this in more detail.
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Old August 17th, 2006, 12:59 AM   #8
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You won't have to reset color balance after changing things like frame rates. It should hold for quite some time, probably many days, maybe until you change it. I often look at my white balance in amonitor to see if the old one looks better than a new one might.
Probably not a bad idea to reset BB relatively often.
In daylight the color will chanmge depending on time of day esp early and late and depending on cloud cover or whether you are in sun or shade. Sometimes a nearby buildings color or lots of green reflection from grass or foliage can through it off.
Personally I find the pre-set to be a bit cold looking especially under cloud cover or shade.
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Old August 17th, 2006, 09:44 AM   #9
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A couple of thoughts:

I, like a lot of people, carry a pocket-sized sheaf of CC filters in various colors and densities. I suppose they're commercially available; I made mine out of old Kodak gelatin filters I had. If a regular white balance makes the scene look too blue, for example, I'll re-white balance through a CC blue filter, which pushes the image toward the yellow (i.e, away from blue). I can also gang up a blue and a cyan to push the camera toward orange... you get the idea. It's far more controllable than just the red/blue color temp shift built into the camera. It's also the only way to push the image toward/away from green (in fluorescent situations), etc.

For what it's worth, faded bluejeans also make a good white balance card when you need to really warm up a scene. You'd think they're way too blue, but they're not.

As for black balance, most manufacturers recommend black balancing at least once a day. Among the things black balance does is squelching bad pixels. If you have a pixel that falls outside the normal acceptable range of brightness, the camera will electronically substitute information from the pixel next to it. That 'map' of bad pixels is maintained in memory. When the camera is powered down for a long time, that memory is erased and you'll need to black balance again.
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Old August 17th, 2006, 10:12 PM   #10
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Yeah Leonard - I guess I did find the preset to be just a little cool. I am going to buy some Warm WB cards or make some myself. Nice to know I don't have to reset after the frame rate change too. I do plan on trying Roberts suggestion to alter the Preset w/color menu.

Man, I never would have thought to WB off a pair of jeans though. (Did you ever see that movie starring Ryan O'Neil where he invents these see-through jeans? Saw it as a kid and it must have messed w/my mind...)

Anyhow that BB mapping is a great feature. I've heard of people massaging dead pixels to life in LCD screens, but that function is pretty cool and I bet something not many people know about. Thanks Scott.
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