Help needed on settings for flash use!!

Hello,

I have never shot with a speedlight flash, I now have a 380EX to use with my 400D and have been asked to shoot some social pics and pics of artists at an art show tonight. The room will be reasonably dimly lit. I have pretty much no idea what settings I should be using. Can anyone help me? Everything from ISO, apeture, shutter any help will be greatly appreciated, Thanks!

Not familiar with the controls on the 380, but if there is an AUTO or E-TTL setting, use that. Set the camera on Manual, with a shutter speed of 1/60-1/80, ISO 400. Assuming you are using the 18-55 lens (not the best for indoor flash use), start with with the widest available aperture. Watch your histogram to get your exposure. If you're underexposing open the aperture wider, increase the ISO or increase FEC. If overexposing, use a narrower aperture or reduce FEC. Use shutter speed only to control ambient light. A slower shutter will allow more ambient light in the exposure. Increasing it will reduce it. If ambient lighting is incandescent, you may want use it to add a little warmth to the photos. If it is flourescent, you won't want any. Also remember that higher ISO is going be add more noise, especially in under exposed images, So try to keep the histogram weighted to the right side.
OTOH, setting the camera to green box mode and flash on auto will probably get you there too...