EX-1 Picture Profiles and White Balance Settings
 

I have Bill Raven's picture profiles loaded into my EX-1 and noticed that one of the settings under the pictures profiles menu is for "white" (I'm assuming white balance). I'm hoping someone can help clarify things for me. Raven's has the "white" setting in each of his profiles set to "5600k Preset". I've always kept the camera's default WB preset at 5600k, however, I hardly ever use it, as I typically do a custom white balance every time I shoot, saving it to the A and/or B WB custom presets. My question is, what is the relationship between the WB setting in the picture profiles menu and the camera's WB settings.

Because Raven's PPs have a WB 5600k preset, does it mean the PPs will work when the camera's WB setting is on the 5600k preset? Or do I need to go into the picture profiles and reset the White setting each time I do a custom camera WB? For example, I just ran a test: I did a custom WB and stored it to WB-A. The WB was 3600k. Then I went into the PP settings and changed the "white" setting from "5600k preset" to "3600k preset". I noticed that the camera's WB preset was effectively changed in the process and the default 5600k WB Preset changed to 3600k. Oddly, however, when I toggled back and forth between the camera's WB preset and the custom WB-A setting--which are BOTH set at 3600k--there was a slight, but perceptible change in color temperature between the two. Since both are the same color temperature, I assumed there wouldn't be a difference when toggling back and forth. Perhaps it's because one setting is displaying 3600k with the PP settings, and the other is displaying 3600 without the PP settings. Would someone be kind enough to shed some light on what I am seeing here. I will greatly appreciate it.

Thanks so much for any assistance.

Cheers,

-Emile Wamsteker

What are the PP settings?

Not knowing the PP settings, and presuming they are affecting color downstream of the base white balance temperature read by the camera, that is the logical explanation me thinks.

PP Settings
 

Hi Max,

These are the PP settings

Matrix ...............on
Select................hisat
Level..................0
Phase.................-5
R-G...................75
R-B...................0
G-R...................-18
G-B...................-32
B-R...................-27
B-G...................13
Gamma Level.............. 0
Gamma Select.............CINE1
Black..........................-12
Black Gamma..............0

Hi Emile...

Just read your post. White Balance is another way of "normalizing" the camera sensor for the "color temperature" of the light that's illuminating your picture. Very generally, White Balance is around 5600 deg Kelvin for bright sunlight and 3200 deg Kelvin for indoor incandescent lighting. An actual scene can vary from these numbers depending on the light source or light mix.

When one white balances a camera, they are basically making the color interpretation by the camera as neutral as possible. In order for the Picture Profiles I posted to work properly, the camera MUST be white balanced for the light source. Otherwise the PP's are worthless.

Hi Emile and Bill,

According to the post Emile did execute WB to the scene. Then changed the Preset temperature to match (numerically) to what the camera read. When switching between the scene WB and the Preset a shift is observed.

If you can post frame grabs of the scene WB and Preset Emile that would help. Barring that I'd go with temperature shift by numbers not being as accurate as the same number derived from a scene WB. Even though mathematically 3600 equals 3600. Doesn't sound like it makes sense I know. For a cohesive answer to that I'd want to first know Sony's process for programming in Gamma and Red Blue channel response in correlation with the kelvin choices when changing the Preset.

Hi Emille

The PP settings give you the ability to specify the preset colour temperature, I guess because you might want it to be appropriate for where you predominantly use the camera. If it lives in a studio, 3200 would make more sense than the 5600 or higher for outdoors use. You could have some PPs that you use in daylight and others in studio, so might want a different preset WB.

However, it is only the preset, and is only used if the switch is set to preset. If you do a white balance (or use ATW) the preset value makes no difference.

N

First I want to thank you all for helping me on this.

I am still not entirely clear, but making progress.

It may help for you to know how I understand WB and tell you how I have my WB workflow set up.

The EX-1 has a WB toggle switch on the side with three settings: PRST, A, and B. I know you know this, but please bear with me, I just want to make sure we're all on the same page.

PRST is the factory preset which comes shipped at 3200k. A and B are programmable for custom WBs. Actually "B" comes shipped in Auto Trace WB, but it can be configured as memory, which I have done.

My setup: I changed PRST from the factory preset of 3200k to 5600k (for run 'n gun situations outdoors when I don't have time to do a custom WB). I programmed "A" to 3200k (for run 'n gun situations under tungsten when I don't have time to do a custom WB). "B" is for custom WBs only. Because I try to custom WB as much as possible, I am mostly toggled to the B setting.

So, when I do a custom balance (toggled and saved) to B memory, are my PPs pulling those WB numbers? I ask this question because when you go into the PPs menu [PICTURE PROFILES>SET>WHITE>PRESET WHITE: (color temperature)] it appears that it is set up to pull whatever number is associated with the PRST toggle--in this case 5600k. If it is pulling 5600k, and I am toggle to "B"--which is, say 3600k--then there is a problem.

More clarification will be greatly appreciated.

Emilie....

Several comments:
firstly, the EX1 should use whatever WB setting you have selected with the switch, regardless. A= custom preset, B= custom preset, PRST=3200 or whatever you've set in the PP menu.

Having said this, I believe there is some evidence that the WB derived from pressing the WB Button, on the front of the EX1, is not exactly correct. IOW, if you see a difference between an embedded preset of 3200 and a "calculated" 3200, I would assume the in-camera preset is correct and the "calculated" 3200 derived from pressing the WB button, is not correct.

Just as a side note: I hope you're taking your WB measurements from an evenly illuminated white or grey card. It's very important that the white/grey card you use to set the WB is illuminated by the overall illumination source and not influenced by a colored reflection off of a nearby specular source like a blue wall, red brick wall, or whatever.

Hi Bill, and Max,

That's perfect. All right, so I'm good on the PP white setting. WB values go into PP based on my external toggle switch position.

About the difference between the calculated and embedded preset? The camera is programmed to show the color temperature in 100k increments. It does not break it down into single unit values. Could it be that the true reading is somewhere in between? For example, in this situation, I did a white balance and the number that came up was 3600k, which I saved to "A" memory. Is it possible, for example, that the true calculated reading was 3649, but a NUMERIC value of 3600k was shown because it needs to round up or down the numeric display value to the nearest 100k? However, the IMAGE itself is displayed on the monitor using the under-the-hood true value of 3649, and this is why there is a difference between the embedded 3600k image (which is a true 3600k) and the calculated 3600k image, which is really 3649 with a displayed numeric value of 3600k? I should mention the shift is very slight, but perceptible. If this might be the case, could a 49k shift even be seen?

Hi Emile and Bill and Nick,

It's a good question I think.

Can't speak for what is happening inside an EX camera until I run it by an EX engineer although traditionally that's how it works. What the temperature meter in your camera reads is accurate to its photocell but the readout is rounded off to the nearest 100k even if the actual temperature is in between the 100k space. As I understand it, this by reason of 100k jumps having been determined to approach the limit of perceptual color changes and being easier to work with when matching temperatures with other cameras and lighting.

You said it's a slight difference and that is making sense. That's why I asked if you could post frame grabs since I don't know how good your eyes are.


I'm assuming the opposite Bill. Until I know Sony's engineering steps that determined what for example "3600k" is supposed to be when programming the Preset position, between custom and preset WB I'd call Preset inaccurate. Sadly there is no accepted industry standard for the photocell designs going into devices when it comes to reading temperatures. Take 5 cameras and WB on the same card and you will get 5 different readings. This is also the case with color meters.

Max,

I will post some frame grabs tomorrow. I guess I can post them directly to this thread? I'm new to this forum so I'm not sure. Looks like I can.

Thanks for the feedback.

Cheers,

-Emile Wamsteker

FYR
http://www.dvinfo.net/conf/sony-xdca...b-results.html

Hey Bill,

Haven't read that thread yet, but I will. Thanks.

Max,

Attached are two files. Both were created with all the camera settings in manual mode. No AWB, no auto Iris, no nothing. I was shooting through a Letus adapter with a Canon 35mm 2.0 wide open. I didn't manipulate the images in any way. I transferred them to FCP via XDCAM and then exported them as still images from FCP.

One file, pictured to the left, titled EMBEDDEDPRST3600, represents a frame grab from footage when shooting toggled to PRST (at 3600k). Just to remind you, the PRST setting was originally set at 5600k, but I switched it to, 3600k through the PP menu [under PICTURE PROFILES>SET>WHITE>PRESET WHITE: 3600] before shooting the clip. The other image, pictured to the right, represents a frame grab from footage when shooting toggled to the WB "A" setting which custom white balanced to 3600k.

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.

What is the light source?

The preset white balance settings assume a pure full spectrum light source while the manual white balance will to some degree compensate for light sources that are not full spectrum or have peaks in some colours. For example light reflected by some materials or paints may not be full spectrum as some wavelengths may be absorbed by the material. Normally you would expect a manual white balance to give you the purest whites for the given lighting while the preset will give you a close approximation.

One advantage of using a fixed preset is that it can make grading easier as you have a consistent setting to start with. 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.

Hi Allister,

Thanks.

The light source is window light on an overcast day. I guess what we are trying to figure out is why two separate 3600k readings give different results. One of the readings was created and saved to the WB "A" memory, and the other is the camera's embedded preset of 3600k. I suspect the difference lay in the rounding up and down of numbers by increments of 100k. While the camera may display a numeric value of 3600k, the true value (which could be 3649, or some variation thereof) is reflected in the actual image.

As much as we want to be scientific about this, the true tolerances of WB and PPs are not as tight as most of us would like, and only a Sony engineer would be able to explain the discrepancy I've found here. That said, I've learned a couple of valuable things out of this: take care to white balance your camera properly and choose the picture profile most appropriate to the given scene. Further, keep your head about you and realize it ain't gonna be perfect but that you should be close to the desired result. In the end, it will be refined in Post anyway. The idea is to try to come as close in-camera as possible to minimize the amount of time spent tweaking in FCP later.

Thanks again, everyone! Especially Bill for generously sharing the picture profiles he built.

Cheers,

-Emile Wamsteker