I have a problem with picture resolution and can't figure out why.

I have my Buzz HDMI output connected to a rasfox splitter.

One output from the splitter goes to my HDTV and the picture is perfect.

The other output from the splitter goes to an HDMI-AV converter.

The AV cable goes to a 16x9 SD TV and the picture is nice and clear but it only shows about 25% of the image (it overflows the screen, it needs to zoom out to show the entire picture.)

Any idea if/how this can be resolved?