Lately I have photographed some projects with flash like for weddings or actor portraits. Since I come from film lighting I feel quite a challenge in using the on-camera flash: The quality of lighting is harsh. The direction is right into the face of the object. The color of the flash has 5600 K. The reflection in the eye is sharp and dead center of the pupil. So what do I do to circumvent the negativ effects?
I prefer to use flash only as fill. I try not to overpower the available light. Sometimes it's tricky. One key is to look out of the best lighting on location. I set the ASA and F-stop for the amount for the natural light. Only then I add some fill. I put my flash 1 or 2 stops under. And I use full or half CTO or CTB gels taped to my flash. I try to come close to the existing light temperture. (Nikon has plastic covers in CTO - I could not get it for my Canon flash. Maybe it's out there, but I could not find it). I hate the hard little highlight pins in the pupils. I do not think there is any way to avoid that with on-camera flash. There are little chimera like softboxes for the flash. It's no help, really. And I do not like it to much to bounce from the ceiling for portraiture. You'll get too much light from the top, dark eye shadows, no eye light and brightness on the hair. Solution: What I do is photoshopping. I take the original reflecion away and paint a new one on the pupils. Much better!