Just keep in mind that one 'stop' worth of exposure time is a factor of
two, while one stop difference is a factor of about 1.4 (or 0.7), since
exposure goes as f/stop squared.  That is, going from f/5.6 to f/8 is
one stop difference, and would take a doubling of exposure time.

Eyron wrote:
> 
> If I have a set shuuter speed (ie sync at 1/125 sec) and the correct
> aperature reads say  F9 .
> But I need a lower F stop to limit depth of field.
> Will minus 3 stops of exposure control alow this and give me a 3 stop larger
> aperature?
> Also what would my F stop be here?
> Are there any drawback to use exposure compensation. ( ie noise etc.).
> 
> EEO

-- 
Don Stauffer in Minnesota
stauffer@usfamily.net
webpage- http://www.usfamily.net/web/stauffer