Odd experience with WB

Hello hello

Yesterday I attempted to take a photo outside after picking a half bushel of beets. I laid white paper (several layers thick) on top of the bushel and took a photo. Then I told the camera to use that for WB and it gave me an error saying something to the effect that the image selected may not create proper WB. So I did it again 3 more times and kept getting same error.

After all that, EVERYTHING looked very green (white paper, wood porch, sky, etc.)

So then I set it to auto WB and the green went away.

Any idea what happened?

judydelo1 said:

Hello hello

Yesterday I attempted to take a photo outside after picking a half bushel of beets. I laid white paper (several layers thick) on top of the bushel and took a photo. Then I told the camera to use that for WB and it gave me an error saying something to the effect that the image selected may not create proper WB. So I did it again 3 more times and kept getting same error.

After all that, EVERYTHING looked very green (white paper, wood porch, sky, etc.)

So then I set it to auto WB and the green went away.

Any idea what happened?

Click to expand...

most likely your sample WB shot was over exposed, so the camera couldn't use it properly, and that's what it was warning you about. Next time look at the histogram and make sure there's no blown highlights (no blinking pixels) in the WB shot.

judydelo1 said:

Hello hello

Yesterday I attempted to take a photo outside after picking a half bushel of beets. I laid white paper (several layers thick) on top of the bushel and took a photo. Then I told the camera to use that for WB and it gave me an error saying something to the effect that the image selected may not create proper WB. So I did it again 3 more times and kept getting same error.

After all that, EVERYTHING looked very green (white paper, wood porch, sky, etc.)

So then I set it to auto WB and the green went away.

Any idea what happened?

Click to expand...

Not all white paper is equal to white, a gray card would be better.

Generally that error means the white paper is over exposed. This is one of the issues with using a white target. Many people prefer a neutral grey target as you are less likely to over expose it.

If you do use a sheet of white paper, you should watch out for paper with optical brighteners. Brighteners glow a little bit when exposed to UV light. This can make your whites look "whiter than white". The problem is that if your light source contains UV light (and sunlight falls into this category), then your "white" sheet of paper may have a slight blue tint. Not a good choice for a white balance reference.

For the same reason you may want to avoid using clothes as a reference target. Many detergents will add optical brighteners to clothing.

judydelo1 said:

Hello hello

Yesterday I attempted to take a photo outside after picking a half bushel of beets. I laid white paper (several layers thick) on top of the bushel and took a photo. Then I told the camera to use that for WB and it gave me an error saying something to the effect that the image selected may not create proper WB. So I did it again 3 more times and kept getting same error.

After all that, EVERYTHING looked very green (white paper, wood porch, sky, etc.)

So then I set it to auto WB and the green went away.

Any idea what happened?

Click to expand...

Could you show the shot with white paper that you tried to use for white balance reference? Was that paper glossy, glossy/reflecting, or occupying only a small portion of the frame?

That makes sense. Thanks! I thought something was wrong with my camera for a minute.

dwalby said:

judydelo1 said:

Hello hello

Yesterday I attempted to take a photo outside after picking a half bushel of beets. I laid white paper (several layers thick) on top of the bushel and took a photo. Then I told the camera to use that for WB and it gave me an error saying something to the effect that the image selected may not create proper WB. So I did it again 3 more times and kept getting same error.

After all that, EVERYTHING looked very green (white paper, wood porch, sky, etc.)

So then I set it to auto WB and the green went away.

Any idea what happened?

Click to expand...

most likely your sample WB shot was over exposed, so the camera couldn't use it properly, and that's what it was warning you about. Next time look at the histogram and make sure there's no blown highlights (no blinking pixels) in the WB shot.

Click to expand...

Very interesting! I'm sure that's what happened because the same stack of white paper worked inside and away from direct sunlight.

Michael Fryd said:

Generally that error means the white paper is over exposed. This is one of the issues with using a white target. Many people prefer a neutral grey target as you are less likely to over expose it.

If you do use a sheet of white paper, you should watch out for paper with optical brighteners. Brighteners glow a little bit when exposed to UV light. This can make your whites look "whiter than white". The problem is that if your light source contains UV light (and sunlight falls into this category), then your "white" sheet of paper may have a slight blue tint. Not a good choice for a white balance reference.

For the same reason you may want to avoid using clothes as a reference target. Many detergents will add optical brighteners to clothing.

Click to expand...

This is the white paper shot outside prior to everything becoming gree

Iliah Borg said:

judydelo1 said:

Hello hello

Yesterday I attempted to take a photo outside after picking a half bushel of beets. I laid white paper (several layers thick) on top of the bushel and took a photo. Then I told the camera to use that for WB and it gave me an error saying something to the effect that the image selected may not create proper WB. So I did it again 3 more times and kept getting same error.

After all that, EVERYTHING looked very green (white paper, wood porch, sky, etc.)

So then I set it to auto WB and the green went away.

Any idea what happened?

Click to expand...

Could you show the shot with white paper that you tried to use for white balance reference? Was that paper glossy, glossy/reflecting, or occupying only a small portion of the frame?

--
http://www.libraw.org/

Click to expand...

The shot was taken using manual exposure, which is not good for white balance, unless you set the exposure carefully.

ExposureTime: 1/5

FNumber: 9.0

ExposureProgram: Manual

ISO: 200

Yes, you overexposed it completely, but not because it is a shot of white paper. Unless you use auto exposure or watch the blinkies same can happen with gray

--
http://www.libraw.org/

I had to look up what "blinkies" mean - and see you're referring to highlights alert. I didn't have that turned on but I will from now on. Thanks!

Iliah Borg said:

The shot was taken using manual exposure, which is not good for white balance, unless you set the exposure carefully.

ExposureTime: 1/5

FNumber: 9.0

ExposureProgram: Manual

ISO: 200

Yes, you overexposed it completely, but not because it is a shot of white paper. Unless you use auto exposure or watch the blinkies same can happen with gray

--
http://www.libraw.org/

Click to expand...

judydelo1 said:

I had to look up what "blinkies" mean - and see you're referring to highlights alert.

Click to expand...

Yes.

judydelo1 said:

I didn't have that turned on but I will from now on. Thanks!

Click to expand...

I would say that because of how cameras are designed, using auto exposure for white balance is less prone to user error and takes less time; at least until you are very comfortable with manual exposure.

Might just be me only.

AFAIK, white paper are actually not white and might not be a good idea to use it to set WB.

Quoted the following from https://www.pointsinfocus.com/learn...-white-balances-why-not-to-use-printer-paper/ :

"the common copy or printer paper, which usually contains optical brighteners-chemicals that change the color response of the paper-can lead to bizarre and incorrect results under some conditions."

Since I use mirrorless camera and shoot on live view, I can see the WB in live view and if I am not happy with it, I adjust it to use the other preset value. If I still can't get the WB to my satisfaction, I would put on a <US$2 WB camera cap (like this) on my lens, take a shot to set my custom WB. Mostly I could get my right WB at that point without going for more expensive grey cards, or correct it in PP.