Okay, I know this might be an unorthodox question, but if you had roughly the amount of money to buy a new EF 100mm f/2.8 or a 580EX II, but not both, which would you buy?


I already have a 17-40 L and a 28-135 (which came with my 40D) so I have the 100mmfocal length covered, but I don't have macro capability. I have found myself becoming fascinated with shooting flowers lately, so the closeup perspective along with a deeply blurred background has me fired up. To be honest, I haven't been blown away by the 28-135's sharpness, and the fact that it is only f/5.6 at the long end makes it tough to get good shallow DOF. Also, light gathering has occasionally been an issue, when handheld at least.


On the other side of the coin, there's the flash. My camera already hasa built-in flash, which I haven't really used that much. Alas, the few times I've used it, I haven't been impressed with the resulting images. Is it because the built-in flash isn't good enough?I don't know. Reality is that I'm probably just not skilled enough yet at flash photography to make the shots come out like I envision them, but I suspect a better flash would give better results.


One of the things I do with my camera is use the 17-40 for interior architectural shots of finished systems for work. If I do get the flash, I need one that can trigger multiple flashes in umbrellas (eventually). That is why I am looking at the 580EX II instead of the 430EX II.Well, that and the fact that the 580EX II works directly with the camera for flash settings, etc., and apparently the 430EX II doesn't.


I look forward to the input!