Canon Speedlite 580EX II Flash is fully compatible with all EOS SLRs, it offers maximum Guide Number of 58 at 105mm setting (GN 190, feet), and supports E-TTL II/E-TTL/TTL autoflash and silent recycling.
The Speedlite 580EX II is dust- and water- resistance, making it possible for users to use flash safely when shooting in dusty or wet environments with EOS-1Ds Mark III/EOS-1D Mark III.
Read moreCanon Speedlite 580EX II Flash User Manual, Instruction Manual, User Guide (PDF)