Hello! I was wondering the differences between these three speed-lights? One is $600, the 580 is $500, the 430 is $270. I am new to photography (check out my photos here seroptics.com) and I noticed that I have problems shooting stuff indoors. Outdoors the image quality turns out to be good. The indoor pictures, no matter how good the composition, shows up as grainy. I would like to fix this. A friend of mine at a dance allowed me to borrow his speed-light and I was able to take better photos indoors that aren't grainy. If you look at the album here, http://seroptics.com/formal-ceili-2012/, you can easily tell the difference between the pictures that was shot using the camera's flash and those of a speedlight. My friend used the 430EXII. I was wondering if I should just stick with that, or will a 580 or a 600 one show noticeable improvements that is worth the money? I was wondering if I should go ahead and invest on a $600 600EX-RT or stick with the 430? My camera's flash won't suffice. Thoughts? Can you compare and contrast? What are the pros and cons of each?