Hello everyone, I wanted to ask how do I get very sharp faces, when photographing a group, specially if I need to have my F as low a 4.0 due to low light and maybe the shutter at 30 or 40, I could also use flash to bring up those numbers but what if can't?
Does the lens quality help? where or on who do you focus on? or what parametter do you use on your camera?
Does using a flash fixes all those problems?
Thank you very much
Gerry.

This isn't a lens quality situation - unless the lens is really bad, I guess... Even at 1/30 or 1/40 people can still move a little bit, and any movement can mean that your images won't be sharp. How big of a group of people? Are you using a tripod? What about ISO speed - you might be better off at ISO800 and a little bit of noise than an unsharp image, for example.

Camera shake by the photographer is usually the biggest culprit for out of focus photos at small apertures and slow shutter speeds. I have taken many group photos and I always, always use a tripod with shutter release cable. This eliminates camera shake. Also, tell the group of folks when you are about to release the shutter and tell them to hold still. A photographer has to control his subject(s) or there may be focal chaos. Hope this helps!

I agree with the post about the lens. It would have to be a lens with serious problems to affect the focus of the picture. From my many years of experience, if the photo comes out crummy, it's my fault.

# of people is between 6 to 12.
No I did not use a tripod but I did told them not to move an inch and I used the standars, stay as still as possible, and take a breath before shooting.
when focusing should I focus on one face and reposition the camera?
How can ISO 800 help me? I never heard of that before and I thank you, I will do some tests now.
Thank you.

ISO is the sensitivity of the sensor (or film) to light, it multiplies the light received (also multiplies noise). In this way, you can use faster shutter speeds, or bigger aperture.
The flash can help even with slow shutter speeds, because the light is so bright and fast that it defines the nearby subjects. This is called "slow sync flash", and has the advantage of keeping the background brighter than syncing at 1/200, but you must keep the camera still to avoid motion blur.