Hello, I'm absolutely new to flash photography; actually, I prefer tu put the internal flash always off so there won't be any harsh light. Is there a way of using the internal without getting harsh lights or do one needs a external flash. Is an external a must-have for every photographer? If so, is there any (really) big differences between the SB900, SB800 and SB600 of Nikon? For an overal flash, which one would you recommend? A lot of question, hope to get advice from here! Thanks! G.