hanging a light fixture over a bathtub ?

[GoldDigger]

Bes-- the measurement is from the rim of the tub in this case. There is no fixture that will be more than 8' above the rim. ...

Unless, of course, it is a sunken tub.
For a shower, the datum line is the top of the threshold, so you might make it with a 9' ceiling. But in a shower it is a bit more likely that it will be hit by backspray.