I have been interested in expanding my speedlite\flash\strobe\lighting techniques\setup for a while now and I think I have finally come to a conclusion.
I am thinking about buying a used 550EX to use as a master to my 430EX. I mainly want to first experiment with off camera flash, along with, possibly, growing in my portrait skills by adding the extra flash\light for that bit more of a way to make the photo pop.
The reason why I am leaning towards the 550EX is because: I am 15, and I don't have a job (I work as an assistant photographer, but that is only occasional and on those occasions it does not pay much). So I am looking for a decent flash that can be used as a master, but still be within my budget.
After reading around it sounds like the 550EX is actually better than the 430EX in a few ways:
- Wider range of power
- Master OR Slave
There are also a few cons\downsides to the 550EX such as a slower recycle time (compared to my 430EX). But since this flash will only be used when wanting to use both of the light sources, I don't need quick\rapid recycle time. When I need fast recycle time I can, and will only use my 430EX.
Anyway... I was just wanting some other opinions on this idea\plan! Thanks!
Canon PowerShot G12
Canon EF 70-200mm F/2.8 IS 
