How to identify flash exposure amount when shot on ETTL

[steamboatscott]

Let's say I set my camera to manual, dialing in my exposure and aperture, but leave the Canon 580 EX II on ETTL. Hit the shutter and the flash determines for me how much "flash" to add. Now let's say I want to manually dial that exact amount into the flash and take several more on manual flash (so I avoid having the ETTL "guess" different amounts with each take). Is there anything on the camera that will tell me how many stops of flash was added for a given picture on playback? I haven't seen anything in the Canon XSi or even in Adobe Camera Raw that states this.

[inkista]

Nope, not as far as I know. Typically, what you do in this type of situation is, instead of using Manual power levels to adjust, you dial in FEC (flash exposure compensation) on the back of the flash. This is analogous to how when you're in Manual mode on the camera, you adjust either the shutter speed or the aperture, but when you're in Av/Tv mode, you just dial in exposure compensation.

[candleman]

Originally Posted by steamboatscott

Let's say I set my camera to manual, dialing in my exposure and aperture, but leave the Canon 580 EX II on ETTL. Hit the shutter and the flash determines for me how much "flash" to add. Now let's say I want to manually dial that exact amount into the flash and take several more on manual flash (so I avoid having the ETTL "guess" different amounts with each take). Is there anything on the camera that will tell me how many stops of flash was added for a given picture on playback? I haven't seen anything in the Canon XSi or even in Adobe Camera Raw that states this.

well even if you leave ambient (shutterspeed) and aperture the same and you're moving around a room.. the light will bounce differently. so it wont be the same.

BUT.. to answer your question... i dont know about the XSI, but my D80 has allowed me to program a button to lock the flash power.
(it works like exposure lock)

point the camera at the subject, press the lock (FEL ~i think thats what its called~ ) and the flash mades a flash.. and holds that output level.

its useful for balancing fill flash when the subject is not centered in the frame.
(allowing the camera to meter the flash via TTL properly with the lock.. then recomposing, focusing and hitting the shutter release)


i hope i havnt misunderstood what you're asking.