Before I had an incident meter I found the exposure value for the palm of my hand. I metered my hand, then metered a gray card, then compared the two readings. I found, like David did, that my palm was exactly one stop brighter than the middle gray. I'd go around metering my hand, and then opening up a stop. This technique was almost flawless in shade or soft light, but in bright sunlight the natural oil in my skin caused a reflection that led to underexposure. The technique was also difficult to use in side-lighting. Those factors are what began to get me interested in an incident meter.