bought it!
What that red ring do?
Finally found one for under $600. Def not mint on the outside but glass is in great shape, focuses super fast and quiet. Took a few practice shots and liking it so far.
Its the 28-70mm 2.8L (The precursor to the 24-70mm 2.8). Couldnt afford the current version but hopefully this will do ok. Took a few pics outside and the colors are amazing.
Only down side is its still to long on a crop body! Was hoping to replace my tamron 17-50mm 2.8 but might need to upgrade to FF first.
I did notice its a little tight to put on and take off compared to any of my other lenses, but not really a big deal.
dumb test photo