Spot meter technique

I know that spot metering only meters about 2% in the center of the frame.

I think the exposure lock and hold is the key. I remember one time when I was trying to take a picture of a small yellow flower set in amongst a larger dark back ground of forest leaves. When I used evaluative metering, the camera metered the larger mass of background, and the yellow flower was washed out.

The flower itself was off to the side, and not in the center of the frame. If I had centered on the flower and spot metered off it, then locked the exposure, and recomposed the shot, it might have worked.

The key is holding that exposure lock. In my camera. the exposure lock only lasts for six seconds, but by using AI Servo and holding down the back button AF focus button, I can hold that exposure lock for as long as I want while I recompose. The little depth of field preview button on the bottom of your camera will do the same thing. The key is that you can't let go of the  button, or the timer starts kicking in. That's why I use Servo instead of One-Shot, and why I have assigned focusing and metering to separate buttons. The AF button focuses, but doesn't meter.

I don't know how well this would work with a wide expanse. If you meter off the bight blue sky, the darker foliage will turn out black, especially if there is a stark contrast between light and dark elements.

I need to experiment some.

Steve Thomas