James,
I intended to post some pics of the 50 with both tubes and TC but got tied up with the puppies. Sorry about that.

Here's a shot with just the 50 at minimum focusing distance.



Next, here's a shot with the 50 plus a 12 mm tube.



And, finally, the 50 plus 12 mm tube and 1.4 Canon Telextender. Keep in mind that the telextender can't be mounted directly to the lens so it goes after the tube.



This combination won't take the place of a dedicated macro lens but it works just fine. You need to be aware that you lose at least a stop of light with each addition of either a tube or a TC. That's important if you're shooting manually with strobe as I was here.

While I like what I can get with this combo -- and with the 85 as well -- I'm still considering getting either the 100/f2.8 macro or the 60/f2.8 macro. Having a lens that works as a "normal" lens and still will focus down to 1:1 is really nice. More convenient than changing lenses, tubes and TCs. It's more a matter of convenience than image quality in my opinion.

Anyway, here are the shots using the 50. I did the same with the 85 with similar results and a bit more magnification.

Enjoy,

Jim