Metering, White balance and exposure

[Dhanu]

Hi,
I just finish reading Exposure Photo Workshop book and have a question.
What 's the difference in using
- White balance vs.
- Metering (evaluate, spot, etc...) vs.
- Changing exposure steps/units

For example is the subject is dark I can take the meter reading from a dark area to expose it more or I can increase the exposure 1 or 2 steps more.
Can anyone please explain?
Thanks

[RichardTaylor]

White balance is about getting the colour correct.

Metering (method) is how you measure the light being reflected from the scene (If using in camera metering).

I'm not 100% sure what you mean by changing exposure steps/units.
If you mean exposure level increments of either 1/2 or 1/3 F stop that is a decision you need to make. I use 1/3 F stop increments because it gives me a little more control.

Quote.
"For example is the subject is dark I can take the meter reading from a dark area to expose it more or I can increase the exposure 1 or 2 steps more."
End quote

Yes you can by over riding the camera metering "advice" by either dialing in some exposure compensation or shooting in manual with the settings you want to use.

Keep in mind the camera metering system is looking for an "average" (grey) subject to meter from. If you pint it at a dark subject it will try to turn it into a "grey" subject and lighten it too much. You need to reduce the exposure to keep the subject dark.
The opposite applies to light subjects. In other words your camera will try to turn whites into grey.

[Dhanu]

Originally Posted by RichardTaylor

I'm not 100% sure what you mean by changing exposure steps/units.
If you mean exposure level increments of either 1/2 or 1/3 F stop that is a decision you need to make. I use 1/3 F stop increments because it gives me a little more control.

Yes, I'm talking about exposure level increments (Turning the dial while holding the Av+/- button). So if I'm trying to capture an object in a low/high light situation the best method is to get a meter reading off an averagely light object, correct?
Thanks.

[autofocus]

Originally Posted by Dhanu

Yes, I'm talking about exposure level increments (Turning the dial while holding the Av+/- button). So if I'm trying to capture an object in a low/high light situation the best method is to get a meter reading off an averagely light object, correct?
Thanks.

...hmmm, tough to answer when your not sure what the question is. There are some basics that may help. Turning the Av button is used for opening or closing your aperture. In that mode, any change you make to the aperture will only amount to the shutter automatically adjusting it's speed for that aperture setting. (in order to give you what it, the camera, thinks is the correct exposure for that particular lighting...which, again, will be 18% grey) In both Av setting and Tv setting the two modes are linked together..change either one, and the camera will automatically try to change the other. The only way to have complete control over both, and the meter, is to shoot in manual mode (M). In manual, you can adjust both the shutter and the aperture independently of each other thus allowing you control to underexpose an image, or overexpose an image to the various lighting conditions.

[Dhanu]

Sorry, If I was not clear with the question.
I'm not talking about the 'Aperture Priority" mode
I'm referring to the 'AV+/-' button in the back


After I meter an average lit object and still would like to add/remove exposure manually. Is that the only purpose of that control?

Sorry, If I'm making no sense at all :-D

[autofocus]

Originally Posted by Dhanu

Yes, I'm talking about exposure level increments (Turning the dial while holding the Av+/- button). So if I'm trying to capture an object in a low/high light situation the best method is to get a meter reading off an averagely light object, correct?
Thanks.

That's what it'll do...sorry I didn't understand your question

[Dhanu]

Originally Posted by autofocus

That's what it'll do...sorry I didn't understand your question

Cool... Thanks

[Michael_2010]

Use Live View and move the Ev adjustment until you see something you like.

[inkista]

One more small note. With exposure compensation, an EV (Exposure Value) is also known as "a stop". This is a doubling or halving of the amount of light. +1EV is the same as:

• doubling your ISO (e.g., iso 400 -> iso 800), or
• halving your shutter speed (e.g., 1/60s -> 1/30s), or
• opening up the aperture by a full stop on the f-number scale (i.e., f/4 -> f/2.8)

[Dhanu]

Thanks for all the replies.