I shot a wedding recently with a new SB-900. Most of the time I shoot at ASA 1600 with the camera set to shutter priority. Flash was on camera in the standard position. I do switch to from Matrix metering to center weighted depending upon the lighting effect I want … I set the camera to JPEG, High Resolution. I am using Nikkor AF-S 16-85G-ED DX lens. I am puzzled by what I regard as failure to the TTL system to provide enough light in certain situations: a) Small Group of 5-8 people in the side of the hall with a gold drape background about a meter behind the group. (Center-Weighted metering) b) Large group of about 30 shot in the hall with cream colored wall divider about 2 meters behind group. The first was the groom’s family and the second the brides. (Both Center-Weighted) In these last shots I noticed the flash was not putting out enough power. For the second group I set the flash to +2 or +3 EV to get more power out and that solved the problem. (For the underexposed shots I compensated in post processing by adding fill light. But naturally I would have preferred to get it right the first time.) I noticed that if I left the flash set +1 or +2 EV… then close ups would be burned out so this is not an option. My question is WHY? Why didn’t the camera / flash sense this an automatically compensate??? How can my settings be improved?