Specifically, what kinds of situations would you use partial over
center-weighted average, or evaluative over the other two, etc?
In most instances with digicams, you would hope that the contrast range in the scene will roughly fill the histogram without clipping (bunching up) at the high or low ends. This would provide detail in the highlights as well as the shadows. Once the contrast in the scene is greater than what the camera can handle, you either will lose highlight detail (blown out highlights) or plug up the shadows, or both. Evaluative metering usually does a nice job of balancing the exposure, and a look at the histogram will let you know if you need to move this data toward the left to avoid blown highlights, by dialing in some exposure compensation on the negative side. Or, the histogram may crowd the left end, with lots of space on the right end, in which case you could dial in some + exposure compensation.
Sometimes, parts of your main subject may be dark compared to the background, as in an airshow on a bright overcast day. If you want detail in the airplanes you could try spot exposure, although on the D60 that Partial Metering is too broad to be real spot metering. This will expose more directly on the subject. If your subject is a person seated in a relatively dim room with a bright window behind him/her, this could also call for partial metering. However, in both the airplane and person images, if you expose for them correctly, the backgrounds (sky or window) will be greatly overexposed, sometimes to the point where the highlights are completely blown out.
If you want to cut down on the influence of the light background, yet keep more detail in it, the centerweighted average is more likely than the partial metering to give you a compromise that may be acceptable.
Or part of your subject may be much brighter than a dark background, such as an array of Christmas lights on the side of a house at night. Evaluative metering will mostly see dark, and your lights might be washed out or greatly overexposed. Here, partial metering, taken from the lights, would give you the correct exposure for the lights. You would have to expose on the brightest lights, then use the "
" button to lock the exposure, and then recompose.
Another use of this last technique: If you come to a complex scen in terms of the range of colors and contrasts, use the partial metering and focus on something close to neutral and midtone in brightness, press the "
", and recompose your shot.
None of these techniques will make the camera think for you, but if you try them all systematically, examine the histograms as well as the images on your monitor (not your cmaera's LCD!) you will soon be able to know which mode to use when, and how much compensation to add.
You probably knoew most of this, and I apologize ahead of time if it seems I am talking down to you.
--
Walter K
