Cyrix_2k wrote in post #8851660
DC = EF-s
EX = L
HSM = USM
OS = IS
IF = Internal focus (lens doesn't move when focusing)
SLD = super low dispersion I think
ELD = extra low dispersion, I think
ASP = aspherical
APO = uses SLD glass
Like others said, go to the sigma site and it will explain it. Most (all?) DC lenses are EF mount, but don't project a full image circle. You can google and find if it will work on an APS-H sensor. Sometimes the longer focal lengths work fine and the shorter lengths vignette.
APO = Apochromatic
EX = EX finish, its their nice velvetty finish on their EX-line lenses, and yes EX is supposed to be their "L" line, but they also have some stinkers marked EX.
DC = doesn't mean EF-S, only Canon makes lenses in EF-S mount, DC means the lens is designed for the smaller image circle of crop sensors, it will mount on any EF mount tho.
DG = designed for full frame.