White Balance Confusion

[Bluenoser]

I've read a lot about WB, but am a little confused.

In this article Introduction to White Balance it talks about using a white or grey card.

1. Does it matter if it's white or greay?

2. The really confusing part is where it's held up to the camera to tell it what colour is white. Are you taking a shot of the card and using those readings to set your WB before recomposing and taking the shot?

3. What is considered neutral grey? Would that be halfway between darkest and lightest grey?


Thanks for any and all help with this.

Cheers

[kencaleno]

White balance

Where, with film you either shot print film in daylight or with flash indoors, and with slide film, you used daylight or tungsten film, or used compensating filters with these. White balance is Digital’s version-you select a white balance based on the condition of the light you are using, so the camera’s meter allows for white to photograph as white
Auto white balance does a reasonable job most of the time, but it cannot cope in some situations-especially when subject is in deep shadow. You need to know when to use the white balance settings for all situations, and this table will help you understand: ( degrees Kelvin is a means of determining colour temperature)

Sunrise/sunset 2400-3000 Kelvin……………………Use Auto white balance
Tungsten lighting 3200-3500 Kelvin ……………………Use tungsten/Incandescent white balance
Fluorescent lighting 4000 Kelvin …………… Use fluorescent White balance
Early morning/afternoon sun 4000 Kelvin…….Use auto white balance/ --fluorescent white balance
(Magenta filter) to counter greenish cast on skin from foliage if under trees or on really green grass
Noon sun/Sun overhead…5000-6500 Kelvin…………………….use Cloudy White balance
Flash photography in daylight 5500 Kelvin ………………………Use Flash White balance
Deep shade………………….6500 Kelvin…………………………Use cloudy/shade white balance
Shade in daylight 7500 Kelvin ………………………………......Use shade white balance
Heavy overcast, very dark shade 8000 to 10000 Kelvin………Use shade white balance


To set custom White balance: (Nikon)
Select a neutral coloured object to set your white balance
It’s best to avoid using a white target. The camera prefers grey.( Print yourself a grey card: In photoshop- File> New
Click on background square in toolbox
select: red 127; green 127; blue 127 from color chart- Print)


In white balance menu select "Custom"> "Preset"
select "measure"
Press shutter release halfway to return to shooting mode
press wb button until a blinking "Pre" appears in control panel and viewfinder
frame reference (grey card) so it fills the frame
and press shutter release all the way down (Camera won't take picture)
If camera was able to register a value for white balance "Good" will flash in control panel and GD will flash in viewfinder
If lighting is too dark or bright "no g d" will flash in viewfinder and control panel


If you use white in direct sunlight you'll always get a "No Gd" response from the camera because the Matrix meter is rendering it white instead of grey. Thus the trick is to select the centre-weighted meter when using a white reference in bright light and you'll get "Good" from a camera. Remember to set back to Matrix metering as soon as you're done.

Ken

[eric.carson]

Originally Posted by Bluenoser

The really confusing part is where it's held up to the camera to tell it what colour is white. Are you taking a shot of the card and using those readings to set your WB before recomposing and taking the shot?

I'm glad you asked! I was forced into the world correct color tone when my impromtu employed forced a WhiBal card me. Boy the troubles I had figuring out how to use the dang thing. Here are my expirences...

Say you take a white peice of paper out of the printer right next to you. Inside, under flourescent light it looks.... White!

Take that paper outside under streetlights and it looks... White!

Set the paper on fire and it looks... Charred! (sorry!)

Thin thing is your brain adjusts what it "perceives" as white. That paper was really a ugly greenish blue inside, and a horrific orange under the high pressure sodium lamps that the state loves to use. How in the world can the camera tell what your bran thinks? It can't. Short and simple there is no way of telling! But you can get close! There a few ways to use a grey-card that I have found:

1. Calibrate Your Camera! - Somewhere DEEP within your camera is a way to set a custom white balance. Essentially the camera looks at the grey card, sees the color that are NOT grey, like that horrible streetlight orange, and applies compensation to make it white again! HOWEVER This is only usefull where the light will not change, take the calibrated camera inside and everything looks purple! Use this where you are going to be taking a lot of photos under fairly consisitent lighting, like inside a stadium, or under that ghastly streetlight
2. Use The Card As An In Picture Refrence - If you Like doing everythoing in software afterwards just have your subject hold the card for a quick shot, just for refrence, then keep shooting without. MAKE sure your camera is not in auto White Balance mode, or the shots will not be consistent, in other words the camera will try to figure out the white balance every shot, with inconsistent results. Recording in RAW helps, but is not strictly nessasary.

I hope this helped! If you have any more questions or need clarification please ask!