Instruction on using white balance please.

I shoot my large A3 matt card which has a black wedge with small letters R-0,G-0,B-O on the blk .

R-204, G-204,B-204 on the 18% grey wedge and
R-255, G-255, B-225 white wedge.

Then select the image in custom white balance in the menu and select the image. Then change the white balance to the custom white balance setting icon. From there, the custom white balance has been saved in camera so you can return to it by selecting that custom white balance. icon.

Then select the custom white balance on camera and take one of the model holding the step wedge and the rest with out in the studio under flash.

Then load the jpeg files into CS2 and use the eye dropper on sample 5x5 average and click on the wedges and hopefully all the R,G,B reading are very much the same. if not use Colour balance to adjust so the R,G,B Readings are near the same in shadows, Midtones , Hightlights areas when this is done the picture should be correctly Colour Balanced.

Have i under stood it right thanks Jonathan

You've got the mechanics right but its not clear if you understand the concepts.

JOHN54174 said:

Then select the custom white balance on camera and take one of the
model holding the step wedge and the rest with out in the studio
under flash.

Click to expand...

The key thing about custom WB is that it must be performed under the exact same conditions you are shooting under. So it would be best to set the WB in the camera off the card the model is holding in the light you are shooting her in. Shot card, select in menu, set camea WB to custom. Takes about 30sec.

Then after setting the WB take a test shot of the card again. If you compare the two files you should find the second one perfectly neutral. Note that if you are shooting in RAW the Custom WB setting does not affect the way the image is captured. The WB info simply instructs Photoshop how to display the file when you open it.

JOHN54174 said:

Then load the jpeg files into CS2 and use the eye dropper on sample
5x5 average and click on the wedges and hopefully all the R,G,B
reading are very much the same.

Click to expand...

If the readings are not the same it indicates your WB target or camera's recording of it isn't neutral. I note you mention JPG. If you are shooting JPG the compression of the image data may affect the color of the card slightly due to artifacts. It's best to select the area you are measuring and apply a 10px Gaussian blur to it before measure to average out any processing induced noise. All things considered its better to shoot RAW.

JOHN54174 said:

if not use Colour balance to adjust
so the R,G,B Readings are near the same in shadows, Midtones ,
Hightlights areas when this is done the picture should be correctly
Colour Balanced.

Click to expand...

Actually the point of using a gray card target in a test shot is so you can let Photoshop do all the work of color balancing. You simply open the file in levels and click the gray card with the middle eye dropper and both the color and exposure will be corrected to the neutral card. It's not even necessary to have set custom WB when shooting RAW since that process will correct any color cast form the RAW camera data.

The problem I see in your case is that you are not using a plain solid middle gray card like a Kodak 18% or WhiBal but rather a target which is two toned and lighter. WB is best set with a plain gray card.

It's good you are focused on process control, but don't get too hung up on neutral color... The eye is highly adaptable and unless the WB is way off, such as using daylight WB under tungsten light variations from nominal WB will not even be noticed. Also consider that in many situations the ambience of the lighting is created by a deviation from nominal. For example if you set custom WB under the setting sun your sunset shot will look like high noon. To capture the ambience of the sunset you need to set the camera WB to daylight so in captures the ambience RELATIVE to the cooler noon day sun.

CG

Many thanks Chuck.
Jonathan.

Thanks a lot for the explanation Chuck. I'm new ( and not english so please forget my mistakes ) and hesitating between the Nikon D80 and Canon eos 400D, principaly because of WB settings offered by the Nikon and... the color temperature setting. The Canon doesn't offer this setting. Do you think it's a must have ? Is color setting a pre set or is it a manual parameter to adjust the white balance ?

If I can manualy adjust the WB using a grey card on the canon I will chose it, but now I see this color temp setting on the Nikon D80 I'm a bit lost.

I'm a sculptor so I need to shoot both my models and final sculptures under incandescent light or normal fluorescent lamps ( 2700K ) at my studio.
You can see some photos and works here > > http://www.sebzar.blogspot.com

Thanks to you

Seb

Sebb said:

Thanks a lot for the explanation Chuck. I'm new ( and not english
so please forget my mistakes ) and hesitating between the Nikon D80
and Canon eos 400D, principaly because of WB settings offered by
the Nikon and... the color temperature setting. The Canon doesn't
offer this setting. Do you think it's a must have ?

Click to expand...

I would not consider it a "must have". The beauty of digital is its ability to adapt to any lighting conditions. If a custom WB is performed the WB should be neutral and no manual tweeking (i.e. obsessive geeking) is required. The only caveat about custom WB is that it must be redone each time the lighting conditions change.

If custom WB is done in sunlight, but then the photographer moves to open shade under trees the photos will have a blue or green cast because open shade is about 500K cooler and the light reflecting from the trees will make it green. A new custom WB would be needed to make it neutral again.

Sebb said:

Is color
setting a pre set or is it a manual parameter to adjust the white
balance ?

Click to expand...

I'm not familiar with the features of the D80 or 400D (I have a 20D) but in general cameras have "auto WB" and other standard settings such as daylight, overcast, incandescent, fluorescent, and custom WB. Some like the 20D and apparently the D80 allow color temp to be set via degree Kelvin, and allow manual green/red and blue/yellow shifts via the camera menus. (Only obsessive geeks need apply);

Sebb said:

If I can manualy adjust the WB using a grey card on the canon I
will chose it, but now I see this color temp setting on the Nikon
D80 I'm a bit lost.

Click to expand...

Cameras are loaded with lots of features which are of little practical use for most users. The ability to fine tune color balance via a color shift matrix is one of them. I wouldn't base my buying decision on that. I was a life-long Nikon film camera user: Nikonos II (1969), Nikon F (1970), Nikonos V (1985), Nikon N8008 (1990). But when selecting a digital SLR I went with Canon because I preferred the reproduction characteristics of the CMOS sensor and the characteristics design features of the lenses.

Sebb said:

I'm a sculptor so I need to shoot both my models and final
sculptures under incandescent light or normal fluorescent lamps (
2700K ) at my studio.

Click to expand...

Incandescent is actually a poor choice. The camera sees the world through red, green, and blue filters. There is very little blue in incandescent light and most of the noise in a digital image is in the blue channel.

"Normal" fluorescent lamps are also a very poor choice for photography. The most critical criteria for fluorescent lamps is their Color Rendering Index or CRI, a measure of how much of the complete spectrum they cover. Natural sunlight has a CRI of 100 and is the ideal. If you use fluorescent lamps you should make sure they have a CRI of over 90.

Next to daylight strobes are the best source of artificial lighting because they are closest in color temp and RBG balance to daylight. A studio strobe with a softbox typically has a K temp of about 5000K and very neutral WB when custom WB is used. You might want to consider a set of studio lights if you want accurate color reproduction of your work.

CG

ok thanks again

Now I think I'm going to take the canon 400D whitch is less expensive so I can save money for some more serious lighting

I appreciate your quick reply

Seb