I just picked up a pretty nice little deal (50/1.4, Spotmatic SP, Vivitar 135/3.5, flash etc etc) and in the pile was a "Toyo" brand teleconverter (2X). Never heard of this thing. Is it worth using at all or is it cheap garbage? I don't think I'll need it, but don't want to bother putting it up for sale if it isn't worth anything.
