580EX Question

when the flash is in E-TTL does your camera need to be in evaluative mode for best results?

Any of the metering modes will work fine as far as I know. I think the metering works the same for flash. I have found that if you can't seem to nail the exposure you want, use the manual pre-flash/exposure lock button. It makes a difference in some situations. It is known that the flash fires a fast preflash on its own, but it doesn't always corespond with exactly what you want to meter. So every once in a while this helps.

I have used all the metering modes and they seem to work fine for flash.

ok cool that's what I was thinking but I was not 100% sure..anyways thanks for the info..

There is an important concept that should be explained here. Every flash photo is a double exposure - an ambient light exposure and a flash exposure. The camera meters and adjusts for ambient light and flash exposure separately.

The camera's metering modes (Evaluative, CW Average, Partial, Spot) affect only the ambient exposure.

The way to change the flash metering mode is with custom function 14 (Evaluative vs. Average) and by using the * button for Flash Exposure Lock (which uses partial or spot, depending on the camera model).

There is somewhat of a consensus (though it's not unanymous) that C.Fn. 14-1 (Average) works best when flash is the primary light source (indoors), and C.Fn. 14-0 (Evaluative) works better for outdoor fill.