Originally posted by marcusBMG The tamron F series are quite good tc's, 6 elements like the 01F's, though if that's yours I've not seen a PKA one before.
There are plenty of cheap old PKA tc's around to cannibalise into an extension tube - vivitars and other third party brands. Hey I'll sell you an as new jessup one for a tenner!
Yes it does appear to be a quality optic -- I didn't bother doing any valid image tests with it other that to see if it would AF with my lenses (it did as long as they were f/2.8).
I'm a little lost as to what you mean by a "tenner"???
Michael