>>When I shot reception dancing, I always used regular TTL, >with >>the flash set at -1.0 to -1.7 ev, since dancing has so >much >>dark area that the flash will usually overexpose if you >leave >>it at 0.0 ev. >>Also, I always shot raw for dancing, so there would be >more >>room for exposure adjustment later. > >Thanks. Explains my exposure w TTL-BL,...I think my images >were somewhat underexposed. I have a lot of latitude as I >shot RAW and in my estimate underexposure was usually less >than 1 stop, easily corrected. >> >> >>I never used TTL-BL, because it underexposes unless you >boost >>the ISO a lot, which makes noisy images. Also, TTL-BL in >>camera A mode always selects 1/60th sec, and this ends up >with >>way too much ghosting in the faster dancing shots. I like >>1/125th to 1/160th for fast dancing. That will give you >just a >>bit of ghosting to convey the motion. > >I kept iso's between 400-640. >I usually kept shutter speeds 100-200. I often did not get >much of the shutter drag look/ motion blur even if I dropped >to 1/50 sec likely as the ambient light added little.
For TTL-BL to work properly, the camera meter must be centered. In other words, the image should be exposed properly without flash and flash is added as fill only.
If the ambient is underexposed while using TTL-BL, then your resulting images will be often be underexposed.
Normally, TTL-BL should be used in bright ambient conditions with the camera in one of the auto modes, so the meter will center itself automatically. If you use TTL-BL without centering the meter, then your results will be unpredictable and the flash strength will be drastically affected by any lights present in the frame. Sometimes the exposure will be close, but other times it will be way off.
Regular TTL with flash compensation is usually the best choice for low ambient conditions.