in photography both a verb, "to spot meter a scene", and noun "Use the spot meter to get correct exposure".
A spot meter is a light meter with a very tight angle of view, usually less than 5°. Some cameras have integrated spot meters, usually metering at the center of the viewfinder: in some modern cameras you can choose which of various possible spots to use.
To spot meter a scene means to take reading in various areas of the scene (usually a high-contrast one), and then to make an exposure decision. This is usually done using a (you guessed right) spot meter, but it can also be done with a normal light meter by the simple expedient of getting closer to objects.
For example, suppose you have your typical boring midday Alps landscape: white clouds in the sky, grass, dark green pine forest. We are using slide film, which means that we have 5 stops of exposure latitude at most.
Whip out the spot meter, dial it on f 16 (we are boring, we want everything in focus), and start metering. Let us suppose you get:
1/2000 white clouds in the sky
1/500 blue sky
1/250 palm of your hand Why ? Because you know for sure the color of the palm of your hand: it is 9% grey, one stop brighter than 18% grey.
1/60 dark pines
Let us convert that to steps between f stop
s, starting with the grass at 0:
+3 white clouds in the sky
+2 blue sky
+1 palm of your hand It is supposed to come out 1 stop brighter than 18% grey.
-1 dark pines
Now you know what your picture (negative
or slide) will come out looking like if you shoot at 1
16. There will be some detail even in the darkest parts of the pines, but the clouds will be nearly blown out. Forget about stuff under the pines.
This is where the Zone System
begins. And of course, you could have dispensed with metering and used the Sunny Sixteen