Spot metering size

Hi, I am starting to look at using the centre spot metering option on my 30D. But I am getting confused about the size of the spot.

Has anybody got an idea how big (or small) it is, or how to work it out?

I mean, is it the same size as the little red square in the viewfinder, or big enough to fit into the circle?

Maybe this thread should have been started as a discussion on manual exposure techniques. It would be interesting to hear what the general opinions are.

Thanks, ...David

hi
i cant remember but spot meter will only meter on the part you have focused , it tells you in the manual hope this helps

This is what your manual says :

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thats quite helpful, thanks steve

Thanks Steve, but now I feel silly - I checked the manual out before I posted, but I didn't find that explanation. It's clear that the ring marks the spot area.

Many thanks for your response.

David

Just yesterday I was shooting some planes in flight that were back-lit with a bright blue sky. Noticing that the planes were underexposed I tried using spot metering thinking that it would correct for the exposure. The results were not much different from using evalutive metering. So instead I adjusted the exposure compensation by 2/3 and that made a significant difference.

Don1 wrote in post #5857992
Just yesterday I was shooting some planes in flight that were back-lit with a bright blue sky. Noticing that the planes were underexposed I tried using spot metering thinking that it would correct for the exposure. The results were not much different from using evalutive metering. So instead I adjusted the exposure compensation by 2/3 and that made a significant difference.

The 'spot', being somewhat large even at 3.5%, should really be considered to be a 'small area averaging' meter! If the object (e.g. airplane) does not fully fill the circle, the adjacent areas of sky will still be biasing the meter reading in the wrong direction.

Evaluative metering simply is an attempt to take a large number of photos in a wide variety of shooting situations, analyze the brightness of different zones in the photos, and 'program' the meter to behave in a certain manner. PHD (push here, dummy!) mode which might very closely simulate a spot mode in some cases. So it is not unexpected that its result might appear quite similar to use of the spot mode.

Don1 wrote in post #5857992
Just yesterday I was shooting some planes in flight that were back-lit with a bright blue sky. Noticing that the planes were underexposed I tried using spot metering thinking that it would correct for the exposure. The results were not much different from using evalutive metering. So instead I adjusted the exposure compensation by 2/3 and that made a significant difference.

What color was the plane you spot-metered on?