I've never heard of TStops being used on shutters except motion picture cameras. Looks like convertable lens to me.
Originally Posted by PanaDP
Tstops would be far, far closer together than f5.6 and T16. That would indicate a really awful, terrible, horrible lens. A realistic fstop/tstop combination is more like f5.4/T5.6 and even then, the lenses don't tell you the fstop. It's just labelled with the tstop and that's close enough to the fstop for calculations like depth of field that should be done with a geometric measure (the fstop) rather than a measured quantity of light (the tstop).