Thanks for the information! I think I may hold off until I am certain which adapter type I would find more useful (with or w/out glass). I'm still curious how much of the focus end gets cut off by that extra ~0.5 inch. I suppose it would also vary by lens, would it be more of a focus cut-off on prime?

maybe I'll just have to get both and figure out which ones the best. Wheres the best place to purchase them from?