you could probably do with a better background or stand her further away from it
Bruce - have you learned how to use the Flash Exposure Compensation (FEC) controls of your flash? This is different from exposure compensation (EC) set on your camera and different camera manufacturers have different approaches to integrating the EC / FEC controls.
For fill flash, try to set the FEC to +1 so that the fill flash is a stop darker than the ambient light. Otherwise the TTL flash functionality will try to "properly" expose the subject; which is probably not what you are trying to accomplish here. Putting out less flash power will preserve some of the features from the ambient light.
On the FEC, if you want the exposure on the flash to be darker by one stop than the ambient light, would you not set the FEC to -1. Just wondering.
Bruce
Bruce - I could be wrong, so play with it. Unfortunately the EC / FEC integration is different with different camera makers. Traditionally Nikon integrated the two functions (changing EC also changed FEC and vice-versa) but Canon kept them separate (you had to set the values separately), although I had heard Canon may have adapted the Nikon approach in some of their cameras more recently. This is something you need to check in your camera manual.
The important thing to remember is that in mixed light shooting (ambient light + fill flash) you generally want your fill light to be a stop lower (and sometimes more) than your key light. If you are using fill flash you likely don't want your fill light to overpower the ambient; that seems to have happened in your portrait.
I never use FEC as I tend to use flash on manual and in fact the only time I use on-camera TTL flash is in "gun & run" shooting circumstances which I almost never do. As much of my flash work is with studio lights, it's a work flow I am comfortable with. When I shoot speedlights, I tend to use bounce flash or off-camera flash with umbrellas.
If I am not mistaken the EC on the camera is independent from the FEC on the flash on my Nikon camera, and flash.
In this particular case I would set the FEC on the flash (SB600/910) to vary the exposure for fill flash. Setting the EC on the camera would only affect the aperture or shutter -depending on the priority- on the camera, not the flash output.
Manfred, thanks for the information. I was not aware of this until you pointed it out.
Bruce