I grabbed a 100mm f2.8L macro from the Canon refurb site while they were on sale this week. I can't tell it from new. This has to be the most dialed-in lens I've ever seen. This is a 100% crop from center and my focus point was the S in the word Ultrasonic on the lens cap. The plane of focus is almost microscopic and yet it runs right through the center of the S, even though the top and bottom of the S are OOF. We're talking micro-millimeter precision. Amazing.