Practice: Playing octave with the left hand

[twinkletoesfaery]

Need advice for good practices for my pinky, my playing of octave chord can never reach a proper forte let alone ff.  It's never loud enough nor strong, the note played by my pinky is never strong. 

Ta chucksies!

[xvimbi]

If you fix your hand just before (or at the moment of) touching the keys, the force (and therefore loudness) is determined by the force with which you are lowering your entire hand. The pinky is not really a separate unit when playing octaves, so there should not be any difference between the loudness of the thumb and the pinky (I guess one can play octaves purely with the fingers, but that doesn't seem to be the most efficient way).