Lightsphere w/ sigma EF 500DG w/ 300D questions

Hey I just got a sigma EF-500 DG super and I had a question. It seems for some reason when I shoot with my Lightsphere and dome on the sigma the flash is over powering. But when I take the dome top off it meters correctly and looks much more natural. I am bouncing the flash in both situations in a fairly dark small room, and in manual mode. Any reason this would be... the only thing I can think of is the camera or flash is trying to compensate for the diffuser and over compensating.

anyone every run into something like this? I thought the dome top was for closer shoots but for some reason it seems to be causing problems with exactly that.

thanks
Paul

A few sample shots would probably help, along with EXIF info.

I think I figured it out the dome was freaking out the ettl so I just backed of the flash exposure -1 step and it seems to be much better. I looked at the exif after you suggested that and from shoot to shoot they were the same so I figured it was the dome doing something weird and tricking the sensor.

It's just a piece of plastic.

The "sensor" is inside the camera, and the only thing that can "trick" it is light coming through the lens.

The dome on the LS will change the way it spreads the light, and can possibly have some effect on subject vs. background lighting, depending on the ceiling.

Experiment more in different environments and you'll probably figure things out.

hum thanks for the advice.... yeah I am going to work on it tomorrow night. thanks for the info.