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Sony XDCAM EX Pro Handhelds
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Old July 21st, 2009, 02:47 PM   #16
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You guys are over thinking this whole business.

When the camera gives you a color temp estimate of what your white balance is, it is only that - an estimate not an dedicated expensive color meter. Over the years I have seen these numbers vary wildly. They are just estimates from a cheap camera circuit designed to help you have a relative idea of what your color temp is.

The presets are probably more accurate but again they aren't designed to be perfect color meters. The main thing is they are a different circuit so it would be plain amazing if they actually matched. Don't expect 2 cameras to match perfectly and don't expect these numbers to match other cameras. Use a decent monitor if you care about your color and get used to what your numbers actually mean.
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Old July 21st, 2009, 03:22 PM   #17
 
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Leonard...
I agree.
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Old July 22nd, 2009, 05:18 AM   #18
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Quote:
Originally Posted by Emile Wamsteker View Post
The difference is actually more pronounced than I could make out on the camera's monitor. Look at the shadows in the embedded preset version--they shift to cyan.

Anyway, I don't know if I'm splitting hairs here. I am mainly concerned with knowing how the camera "thinks" so that I can control it and therefore can get predictable results.
Well Emile, after seeing the pictures you are certainly not splitting hairs. That is a big difference. It is NOT a difference in between the 100k space. But from seeing them I'm glad to say it looks like there is nothing wrong with your camera.

For an overcast sky through a window the Preset is looking as it should that being more neutral. And the Auto WB is looking proper that being more warm. When you approach 4k especially, and for outdoors, preset will produce a picture more neutral than an Auto WB.

The order of accuracy as I think you know is such:
Preset
Auto WB
Manual WB

*******

General Comment:
Auto WB is pressing the camera's WB button, many
refer to this as Manual WB. This is a misnomer.

What is being increasingly referred to as "Auto WB" with
these sub $10k cameras is more aptly termed
Auto Tracing WB.

"Manual WB" in a professional camera infers manual
balancing of the encoder channels by an engineer.


*******

The preset may look cyan in comparison to the Auto WB here but it is actually more neutral given the light source. I was matching two broadcast cameras (Sony) today and had a similar difference under tungsten. The same experiment under tungsten will show a similar effect with green replacing cyan. Further below...

Do consider any color balance derived from any camera's Preset and Auto WB calibrations is created by the manufacturers inclination towards what looks pleasing for their cameras. An Ikegami Preset will be different from a Sony, from a Panasonic from a JVC. What you are seeing in Preset is the manufacturer's textbook rule of what that temperature should look like, and sometimes this will look ugly because as Alistair alludes that textbook rule doesn't control the lighting in front of the camera. Of course, the other way around hence Auto WB.

One temperature Preset is one thing. Preset temperature programming is another and a relatively unique feature. Thus the question stands on how Sony determined the color balance for the temperature steps. How were the incremental values of gain determined for the R and B channels?

Quote:
Originally Posted by Alister Chapman View Post
...a fixed preset... it is also useful for multi-camera shoots to help get all cameras to match when they can't all white balance together at the same time.
If it is the last resort yes. I'm confident you know they will not match perfectly especially different cameras. More especially from different manufacturers.


Quote:
Originally Posted by Leonard Levy View Post
You guys are over thinking this whole business.

When the camera gives you a color temp estimate of what your white balance is, it is only that - an estimate not an dedicated expensive color meter. Over the years I have seen these numbers vary wildly. They are just estimates from a cheap camera circuit designed to help you have a relative idea of what your color temp is.

The presets are probably more accurate but again they aren't designed to be perfect color meters. The main thing is they are a different circuit so it would be plain amazing if they actually matched. Don't expect 2 cameras to match perfectly and don't expect these numbers to match other cameras. Use a decent monitor if you care about your color and get used to what your numbers actually mean.
Not with you on that Leonard.

One would be wholly justified in expecting your camera to give you temperature readings accurate to it photocell within a range of +/-200k. Beyond this range is NOT an area of acceptable estimation. It is without argument an absolute performance requirement, and any professional camera not performing up to it is technically defective.

Essentially the working solution to temperature readings as they affect color balance variation is familiarity with equipment behavior. Specifically this is by determining numerical offsets. Every piece of gear with a temperature meter inside it will behave differently than the next except for all other things being equal, two identical units.

Leonard, if you light using a "dedicated expensive color meter" the accuracy of the meter is irrelevant vs. your camera. As I've said in the previous posts and other threads you will be dealing with two different photocell designs and deciding on temperature with your meter will not produce that precise color balance in your camera. The only relevance is the offset between your camera and the meter.

In my opinion the video monitor is in a way the blight of video. In essence, a handicap instrument than an instrument for accuracy. There is a wide span of indeterminate variation between phosphor batches and LCD backlights. On the other hand the variation between color meters and cameras is determinable.

FYI, yes you can make two EX cameras match as well as any other professional camera. This is done first through the maintenance menu, not through picture profiles.
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Old July 22nd, 2009, 05:56 PM   #19
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The Missing Manual

Quote:
Originally Posted by Max Allen View Post
FYI, yes you can make two EX cameras match as well as any other professional camera. This is done first through the maintenance menu, not through picture profiles.
Sony is mute on this whole subject because they provide NO information what so ever on the maintenance menu and the most basic of window dressing to make practical use of their picture profiles. Please do share to enlighten the rest of us mere mortals ;-)
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Old July 22nd, 2009, 08:33 PM   #20
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"One would be wholly justified in expecting your camera to give you temperature readings accurate to it photocell within a range of +/-200k. Beyond this range is NOT an area of acceptable estimation. It is without argument an absolute performance requirement, and any professional camera not performing up to it is technically defective."

Max, Its nice for you to set those standards, I've just never seen that kind of accuracy in cameras and I don't think the manufacturers care about it all that much. Just my guess. I remember when the D30 cameras first came out , 3200 degree lights would read as 2200. we got used to it. Sony cameras often used to balance green as a matter of course so we got used to carrying green gel to cheat it back.

Presets look different both because of color temp and the colorimetry and matrixes of the individual cameras. Lots involved.

I would never use a color meter to set my video color balance, just trying to say that I doubt whether manufacturers care that much about this system being accurate.
After 25 years shooting, I find a trustworthy monitor and waveform to be the best way to set exposure and color and don't personally know anyone who prefers any other method. That's why in a well crewed professional situation you usually have a good monitor, a paint box and a tech.

Of course once you know your camera then you can trust how it white balances or what the presets look like - until you've seen the evidence though its a crap shoot.
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Old July 22nd, 2009, 10:08 PM   #21
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Hi Leonard,

My point is if your camera read tungsten as 22k that does not make your camera inaccurate. You said carry green gel so I'll assume this was ENG with varying light sources. As long as it does not read 22k one day and 25k the next. The green issue aside, 22k is accurate to the photocell receptor in that camera so it can be considered tungsten balance for that camera. Now if you're matching another camera which reads the same light as 32k, you know that means 22k in your D30 so you won't raise your D30. Or if you want to cool the image you won't light or balance at 35k you'll raise to 25k.

I haven't seen D30s, D35s, D50s or D55s balance that far off. Not saying you're wrong but I haven't seen it. If AWB yielded so much green that is not normal. Some red or blue is typical of the SD Sonys but not green.

I understand what you mean. Not saying don't use monitors but on the scale of accuracy monitors don't score high in my book. Waveforms are an evolved incarnation of a meter and obviously in the top of that scale. It deserves a look back to note how the film industry developed and matured in this regard. It wasn't with the use of monitors but meters. As you know not having WYSIWIG required DPs to know their cameras and stock intimately, creating the image with care. I think video has been spoiled in that we place unconditional trust in the monitor. So the history of video is wrought with ugly lighting and bad levels. A waveform as you included can solve all that of course.

Meters are highly useful, they shorten lighting time immensely. When I know the sensitivity of a video camera and can match my light meter I no longer need to walk back and forth to the monitor or the waveform while lighting. I basically use them only for a final check this way. Especially useful when lighting something in the distance.

As far as color meters, many many uses. You can pre-balance 1 or 10 cameras to a scene when you've metered the lighting beforehand and you don't have to be on location. On location hook up, turn the cameras on and everything is matched. You can match different temperature sources without a monitor or waveform. You can tune LEDs to not cause false color errors without having a camera up. It goes on and on.

Many video guys are unaware of why or how metering for video can be used. Of course being me I blame this on the security blanket of the video monitor. But if you use a waveform then we can be friends.

Last edited by Max Allen; July 22nd, 2009 at 10:40 PM.
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Old July 22nd, 2009, 10:37 PM   #22
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Quote:
Originally Posted by Barry J. Anwender View Post
Sony is mute on this whole subject because they provide NO information what so ever on the maintenance menu and the most basic of window dressing to make practical use of their picture profiles. Please do share to enlighten the rest of us mere mortals ;-)
Hello Barry,

I have to agree with Sony on being mute on the maintenance menu. It is very simple to mess up your camera with the amount of controls available in there which frankly I was surprised they included, but that's part of the reason why my company bought one.

Please understand I don't want anyone to mess up their camera. To describe it what you'd be doing is what the camera does when you press the AWB button and ABB function. Except you will be doing this manually. Adjusting gain on the RGB channels for White and Black. After this you'd then go into the PPs to match all the gammas, then you will be lining up the matrix.

I can't say how strongly I recommend to stay away from this unless you fully understand what you are doing to the camera. A vectorscope is a necessity, a waveform is preferrable and a test chart with color chips is needed. If you have to do this then have an engineer or DIT perform it. If something goes wrong (which it shouldn't) you at least have some recourse now as they will be responsible for the work.

If you want to get as close to this as possible then perform AWB not using a white card or warm card but using a greyscale. As always the only test charts, be they white cards, warm cards or anything else, I recommend is DSC Labs.

Of course you can always decide to learn camera engineering too. Read, talk with engineers, maybe take a course. There are "engineers" I know who follow some strange processes so let's say it's good part "art" also. I'm always learning myself.
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