WB Confuzzeled

ronlane · Jul 16, 2018

smoke665 said:
@ronlane looks like white balance and color sampler are not quite the same both are 5x5 but WB is image pixels and color sampler is screen pixels. I haven't been home to check but supposedly WB sample size can be changed. the WB tool allows you to change the scale of the sample size...when WB tool is active, check the bottom of the Tool Bar...you'll see a Scale slider that will change the pixels to be used for WB sampling.

I do know that if the cards are angled to the lens you can have some significant differences in samples on the cards

That was the biggest thing I was working with yesterday was keeping it from being angled to the lens. I will check the other.

ronlane · Jul 16, 2018

You can change the size of the picker. While I did not see the slider, I was able to change it using the wheel on my mouse. I can go from 5x5 up to 17x17.

smoke665 · Jul 16, 2018

Okay thought about some things and tried something when I got home. I usually adjust WB from the target without any other adjustments to the file. However the target shot was slightly over a full stop under exposed. I bumped the exposure and then did another WB sample, which resulted in a dramatic change in the temperature of the white card, not so much on the gray or black from the original readings. By bumping the exposure it did greatly reduce the tint adjustment

The first image is a sample of the white card. Notice the temperature and tint adjustment. Previously I was seeing 12,000 temperature and a +20 on the tint. The image here without the drastic tint adjustment isn't all that bad.

Here is the sample of the gray card. The temperature is pretty close to what I was getting before but rather than the tint being completely pegged to the right it's only +14. Again the image WB is not objectionable on my monitor (unlike when it pegged right on tint)

Lastly is a sample on the black. The temperature is very similar to my first readings before I bumped the exposure, but the tint is only +8 as opposed to being almost pegged.

In conclusion, it appears that a underexposed target shot can fool Lr WB tool causing it to bump tint higher. I haven't tried it yet, but I suspect that an overexposed target will likely result in the tint being reduced to much. @ronlane when you were experiencing problems with skin tones, do you remember if your target was underexposed/overexposed by chance?

Unless I'm misinformed pure white is 10k and blue is 25k. So all of these are reading well into the blue light category????? I've had readings in the 6500-7000 range before but never anything like this. I know that plants give off CO2 during the night, CO2 is heavier then ambient air, we were there early in the morning as the reversal in photosynthesis was just starting. and CO2 can block the infrared range. With all the vegetation in the gorge, is it possible that some type of greenhouse gas effect was limiting some of the wavelengths? Been a long time since I was in college and most of that was lost from non use, long ago.