Switched 430 -> 580 exII exposure ?????

I have recently upgraded to a 580 exII from a broken 430. I am having some issues though and have some questions. I am using a gripped 40D. The other day I was trying to take pictures of one of my daughters toys against a white back drop. The camera kept under exposing (white back drop) so i did what i would normally do on my 430. On the camera i would tell the flash to use 1 stop more power. On the top of the 40D just click flash/iso button on top, and turn dial to one stop more power (three clicks)

The only thing was, the flash was still putting out the same power. Picture kept underexposing. It seemed no matter how high i turned the camera flash exposure compensation, the flash would still give same power. I had the camera on is 200 in M mode with (if I remember right) shutter of 1/100 and f/stop of f 5.0. The flash was in ETTL mode. I do not remember if i tried to use the settings on the flash to bump up flash power. What I did find that worked was put the flash in manual mode and set the flash power to 1/2 and 1/4 and 1/32 just trying to find right exposure. I was using a white balance backdrop to set exposer. (target with black Grey and white)

When in M mode the picture would expose right at I think 1/4 power. I know the 580 exII is much more advanced then the 430, it is self exposing? What sort of things do i need to know when using Camera Flash Exposure compensation?

Did you check to see what the FEC on the flash itself is set to? Try setting the FEC via the flash (or the camera menu) and see if that makes a difference (I'm thinking it will).

FEC can be set on the 580exII and also with your 40D camera. There is a clear protocol for which setting takes precedence. Check your manuals. I think PacAce is on to something. Probably FEC was set on the speedlite, so that no matter what you did with the camera was ignored.

Thanks i will check. I don't think i touched the setting on the flash, but I will check.

Forget Flash Exposure Control on a Canon. It's the ETTL flash algorithm that's at fault.

Here's a $1,000 tip for you: Find the ETTL custom function (it was #14 on the 20D) and set it to 1:AVERAGE. Do this when flash is the main light. When it's outdoors and you're doing flash fill, set the custom function back to 0:EVALUATIVE.

That tip will give you drastically improved exposure with your ETTL Canon flash. Severe underexposure is the name of Canon flash unless you set ETTL to AVERAGE.

Most likely FEC is set on the flash. ETTL works fine in evaluative, if you understand it, which is simple if you put in a little time and effort.

I have heard many times that you need to up the setting to +2/3 stop to make it work. That is where I have my flashes set as a default.

tim wrote in post #7285877
Most likely FEC is set on the flash. ETTL works fine in evaluative, if you understand it, which is simple if you put in a little time and effort.

Golferdude1977 wrote in post #7286592
I have heard many times that you need to up the setting to +2/3 stop to make it work. That is where I have my flashes set as a default.

What Tim is saying, is that you need to learn how to use evaluative, and in some cases, +2/3 will be necessary. Other times -2/3 may be necessary. It depends on the scene. There are many good threads here on POTN explaining the pros and cons of evaluative and average.

https://photography-on-the.net/forum/showthre​ad.php?t=604653
https://photography-on-the.net/forum/showthre​ad.php?t=108846

I settled on using Evaluative 100% of the time. Anywhere from +1/3 to + 2/3 FEC. I see no reason to have to learn the idiosyncrasies of two different metering methods. Better to master one. Works great for me.