I recently bought a used EF 300 2.8 IS (version 1) and I think the IS is not working based on my experience with IS on my 70-200 but I would like a back to back comparison. Does anyone have either of these lenses for me to compare with my own? Shoot me a call or a text if you do, please. Happy to drive to wherever you are. Will only need a minute. (434) 409-3767.
Closing the loop on this - I met up with the ever-helpful and all around nice guy Andrew Shurflett and compared my lens to his same exact model. Happily for me, the IS works correctly.
Background info: Canon's IS (VR in Nikonese, OS in Sigman) is pretty reliable. It's unusual to find used lenses without functional IS whereas on some other brands it's fairly common. On big Canon lenses like this, it's more common for ads to state broken AF drive. But whereas on my 70-200 the IS effect is very noticeable, on this one it's small. Half-press, hear the motor whirring, then you get a slight sluggishness of the image moving in the viewfinder whereas on the 70-200 it's like you glued a picture to the front element. Part is due to the longer FL and part is due to different levels of IS (2 stops for the 300, 4 stops for the 70-200).
Bottom line: I'm happy that I got a great, fully functioning lens with perfect glass for a great price.