Metering?

[Snurk71]

I think I understand the difference between spot and multi metering (determining the exposure either on a fixed point or trying to determine the exposure based on several areas in the picture). But it probably wouldn't hurt for one of the experts to explain it.

Also, what is the general guidelines for when to use spot and multi metering?

Thanks

 

[tigger795]

Keep in mind I am not an expert...

You have the general idea correct. Spot metering determines the exposure based on a specific area in the center of your viewfinder. "Multi-metering" uses much more of the area in the viewfinder to determine correct exposure but the center may be weighted more than the rest of the image.

I find spot metering useful in situations where I am concerned about other elements of the picture adversely affecting the subject I am trying to capture. One instance would be backlighting. If I use "multi-metering" in the presence of a brightly lit sky it will be considered part of the picture that I want to be correctly exposed so the camera will compensate for it by either increasing shutter speed or stopping down the aperture, or both, which will cause the intended subject to be underexposed and thus much darker than I really want.

On the other hand if I used spot metering to determine the exposure on just the subject I want to be exposed correctly then that will be less of a problem, however in this situation the sky will likely become overexposed thereby causing loss of detail in clouds. For most landscape shots I think that "multi-metering" would be OK but for portraits spot metering would be the way to go.

Hope this helps...and I am sure if I screwed any of this up I will hear about it shortly.