the user is almost always recommended to use it STOPPED DOWN in actual practice!!!
...from a glamorous F2.8 to a paltry F4...
*fair remark: except the rare few that do actually 'perform' at F2.8 (or lower)
isnt that sort of like buying an expensive suit, but putting aside the classy pants and coat to wear only the white shirt to work, becos the classy pants and coat are somewhat PURPLE