Smaller balloons can be held from above! Trigger set with a slightly longer delay to encourage most of the balloon rubber to recede.
From my second shoot with my new digital sound trigger. A bit more thought to composition and lighting this time round.
Strobist: SB800 on camera left, SB600 behind subject with plexiglass diffusor. Flashes on 1/64th power.
EDIT: DIYPhotography did an excellent write-up on my high speed shots.
EDIT: 2010-06-29 Hello to everyone visiting from the flickr blog! I really appreciate all the comments and feedback. More of my high-speed shots here and a write-up of how I do them here.