Can is use a normal flash for macro photos?
Well, there is the question... i have the Sigma EF-610 DG SUPER flash because i was not able to find a ring flash... this is a very good flash, but i want i to maccro..... it can be useful? what are the drawbacks?
What are you taking pictures of? You can use any flash for macro photography, it just depends on the look you're going for. If you've never done it before, do some testing. Mount the flash on your camera and bounce it off the ceiling, point it straight at your subject, use it off camera (if you have radio triggers or a slave function) in any direction you like.
If you want a ring flash, simply purchase one of the adapters like the one below.
I've got one that I've used in conjunction with a Polaroid 144az for portraits and they work pretty well.