the diff between light metering and WB?

asamuel · April 7, 2006

I am embarrased to ask, I hope I dont offend anybody by doing so...

So Im learning to understand exposure values and the sunny f/16 rule. OK.

but, I think setting the White Balance is a totally different subject, correct?

I think the EV values in light metering (-6 to 23) ARE TOTALLY DIFFERENT to the EV values in the zone system (-5 to +5)

I think I need to re-white balance for every new scene. and that the best way to do this would be with a gray card and the in camera meter or with a seperate, light meter.

Am I any way near right?

wxwax · April 7, 2006

A light meter measures the amount of light coming in to your sensor.

White balance measures the color temperature, or quality, of the light coming into your camera.

They are not the same thing. The greyscale is a good way to understand and control the amount of light coming in. You can have too little, just right, or too much light coming in.

Whereas color temperature, is measured in degrees Kelvin. Higher Kelvin temperatures give you a cooler, more blue, cast to your images. Lower Kelvin temperatures give you a warmer, or more yellow, cast to your images. Color temperature is determined by the light source. Different light sources emit different color temperatures: a tungsten light has a lower temperature than than sunlight, for example. When you adjust your white balance, you're simply trying to get your sensor to correctly read the incoming color temperature, so the colors in your image look right.

One huge advantage to shooting in RAW is that you can very easily change your white balance after you've taken a shot.

DoctorIt · April 7, 2006

asamuel wrote:

I think the EV values in light metering (-6 to 23)

Am I any way near right?

Waxy has already given a good answer - you definitely could use some brushing up on very basic technique, check out some of the books that have been reviewed here at dgrin, click on the books link up top there.

I recommend this one: http://dgrin.smugmug.com/gallery/1089209

I'm just curious, where did you get those values for "light metering", I've never ever heard of any -6 to 23 scale?

While we're on the topic of scales, once you understand EV better, you may want to revisit my next comment. Most digital camera sensors are not capable of handling a full 10 stops (-5 to +5 EV). This standard comes from film, which has a more broad dynamic range, unless I'm outdated, I think digital is at best -3 to +3. This means the range of light that can be interpreted on a single photo without blowing out or being completely unexposed.

asamuel · April 7, 2006

Thanks for your help it is becoming clearer.

I found the EV values in a link from the useful information sticky in Techniques, so I am fairly confident to use it.

http://www.fredparker.com/ultexp1.htm

I would love to read more, but now living in Beijing, its costly and inconvinient to buy books. Useful links on the web would be appreciated.

thanks again

the diff between light metering and WB?

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