Originally Posted by phaseshift
so would it be better to go ahead and go in Manual mode?
Because I found that today when shooting in Av or Tv even though the metering was in the middle some of my pictures came out overexposed or had too much light in it.
So basically when you are in the above settings you mentioned, it will meter but if it comes out over exposed or underexposed I have to changed the exposure to either + or -?
How about if I'm in manual, will I have to do the same?
What camera are you using?
DLSR's aren't perfect at metering. Some camera models are known to overexpose, some underexpose, but typically not by much, perhaps 1/2 to 1 stops (any more and something's wrong).
You also have to realize that even a DSLR sensor cannot properly expose a scene if there is too much difference between the light and dark areas. For example, if you shoot directly at your bedroom window in daytime, the camera will properly expose the window, so that you can see details outside. However, the interior of the room will be underexposed, leaving what appears to be the window "floating" in darkness, or if isn't too bright outside, you'll see just dark walls.
The same holds vice versa. If looking towards the same window, but this time you meter off an interior wall, the window will then be overexposed with completely burned highlights.
In such a scene, most DSLR's cannot expose both areas properly (medium format digital might have enough dynamic range). It's one or the other. This is where techniques like HDR, exposure blending, or post-processing (levels, etc.) comes into play.
Here's an example (not my image):
In this scene, the camera has metered for the darker interior space, but this causes the light from the window (which is much brighter) to be overexposed. Conversely, in the same scene, one could expose for the window, but then the room would darken considerably.
So when shooting a scene, if you know there are extremes of shadow and light, then you must choose what you want exposed properly, the lights or darks (or simply wait until lighting conditions are better, or make it better yourself, do an exposure blend, etc). If I'm shooting a landscape with a huge DR, I will often expose for the skies since they are highlights and in danger of being burned. This will of course darken the foreground, but I just lift the shadows in post.
Sensor size matters a lot for the dynamic range a camera can see. Your typical APS-C DSLR has a DR of about 8-9 stops or so, whereas a full frame can be 10 stops or more, and medium format digital can be 12 or more, and medium/large format film has more still.
Originally Posted by phaseshift
you mentioned metering mode in the guide but not as in depth as I was hoping. Do you have a guide on that?
Also through my liveview/lcd I can move my focus point(?) or metering with the dpad on the right of the screen, how can I do that when I look through the view finder?
Metering modes are distinct from selectable AF points. Most cameras have three modes: matrix (default, aka evaluative, multi-zone, etc.), center-weighted average, and spot. Matrix takes the entire scene into consideration and suggests settings based on that. Center-weighted average does just what it describes, giving the most consideration to the central portion (60-80%) of the image, and spot will meter only 5% of the center of the image (some also have Partial metering, which looks at 10% maybe). Spot metering is useful when shooting the moon at night, for example.