I can't have both, and I'm wracked with indecision over which one would best round out my kit. I have an engagement photo gig lined up a few weeks from now, so it's bringing the issue to a head. Geno P. offered me some advice on a DPR thread. There's a lot of merit in his remark. I've been leaning towards the 105 because of focal length spacing. I like long lenses, and it would complement the 20mm + 28-70 pair nicely, replacing the cumbersome 80-200 for event work. I wonder if it's any better in bright conditions than the 85, which seems to do its best work in the dark? I understand it's reasonably sharp at f/2 as well, which is about as wide as I'd want to go for a portrait. On the other hand, I think the longer focal length might make me lose close contact with my subjects, which is the way I prefer to work. I don't think the 85 would kill my love affair with the 28-70, because it's not AFS, and isn't suited for event work. The 85 has a full f/stop advantage over the 105, and would round out a lightweight prime lens travel kit (20mm, 60mm, 85mm) nicely. To complicate the issue further, Geno went on to say... What kind of problems are these bad samples infected with? If they're common to the lens, it would rule out the purchase of a used copy altogether. I hate to base a $1000 decision on incomplete data and a coin flip. I'd appreciate any input/opinions that owners of one or both of these fine lenses might offer.