I recently just got asked to shoot pre-prom photos for my high school. I'm a little undecided as to which I should buy, a fast lens (50mm 1.4) or a Speedlite (430 EXII). The shots will probably be taken at around dusk times. My fastest lens as of right now is my 40mm 2.8 or my 60mm macro 2.8 (focal range will not be usable for this occasion). Also, if you guys were wondering the flash will be used on camera. What do you guys suggest?