Opteka RL-500 eTTL AF Macro Ring Flash for Canon EOS 60D, 50D, 40D, 7D, 5D, T2i, T1i, SXi, and SX Digital Camera Fully dedicated with the latest Canon eTTL auto exposure Ideal for Close-up photography, especially medical and scientific applications Dual flash tubes can be switched on or off for creative flash control High speed synchronic flash Guide number of 18/m, (ISO100)