Re: Help with washed out sky
The maximum flash sync speed of the 40D is 1/250. You need to turn on the high speed sync of your flash to allow faster shutter speed. I don't know if the 220 has that function.
Re: Help with washed out sky
Use manual setting on camera. Set the f-stop to 16 and set the flash to manual and full power. Experiment you may have to open the aperture up a little if the flash isn't powerful enough.
Re: Help with washed out sky
I'd suggest playing with a polarizing filter, and then play with the curves.