ISO Boost. Namely ISO 50. Is it really 50?

I tried searching but didnt see anything about it.

I always thought that ISO 50 was better than ISO 100 but I read somewhere the other day that "50" is really just more of an in-camera trick on 100 ISO than anything else.

How exactly does the Boost feature work? Or, more precisely, what exactly does it do to the picture?

it overexposes by a stop then brings it back down. generally it will not change the visual dynamic range, though it may cause early clipping (not likely if you are using iso50 anyway, since you'de likely be shooting in situations where everything's still and probably have a wide angle with some sort of filter on it). it's suggested you use an ND filter instead

basroil wrote in post #4028542
it overexposes by a stop then brings it back down. generally it will not change the visual dynamic range, though it may cause early clipping (not likely if you are using iso50 anyway, since you'de likely be shooting in situations where everything's still and probably have a wide angle with some sort of filter on it). it's suggested you use an ND filter instead

So as far as IQ goes, is 100 better than 50?

Yes, most of the time..

Hermeto wrote in post #4029270
Yes, most of the time..

true, but as hermeto said, most of the time, since sometimes the extra time the shutter is open can give you dramatic improvements (water down streams for example)