Flexible and resistant diffuser, I do not regret my purchase! Compatibility confirmed on SIGMA EF 530 DG SUPER and as well as the Canon 580 EX II. It can even be used to soften the camera flash on canon 550D which is often too powerful, it is sufficient when the flash unfolded position the smooth upright! Although a white sheet A5 (A4 folded in two) can do the trick, or a white post-it, this diffuser is constant in the result and allows a better progression in the use "subtle" flash. Moreover this is the kind of accessory that always fits in a camera bag: strong, lightweight and not bulky! (Houses broadcasters often end up wrinkled or damaged ...)
