As far as I know, if you set these, it helps you with estimating what the reach of the flash is at those camera settings. But if you have the flash set in manual, 1/4 output will still be 1/4 output, the ISO or aperture setting do not make the flash more powerful. The zoom setting does. Someone told me recently that the ISO setting on the flash did change his flash output in manual mode, but I do not believe that to be true.