And make this totally useless thread more interesting and so undeserving of deletion?

Not a chance

OK, no worries as I have now found out but am unable to delete this totally useless thread

As I understand it the APO EX and the APO DG EX are the best .. things went downhill from there with the Macro and HSM versions.

I may well be totally wrong but went with the APO EX anyway as I got it for a decent price on Ebay, the DG has a (supposedly) better coating for digital that reduces flare but how good that is I have no idea.

Mine is very good at 200mm, even wide open at f2.8.

I do know the HSM versions will not work correctly with the 1.4x and 2x Sigma DG EX teleconverters and this is worth having as they are matched to the lens and actually work very well. (especially the 1.4x).

Have decided to take the plunge and buy a DA* 50-135mm as I have found a pro dealer with one in stock at £529 plus postage but upon contacting him he is not aware that lenses have a 2 year warranty if purchased through a pro dealer and thought it was just bodies.
As SRS offer this I wonder if it is a Pentax thing or something just Chris offers?

Mine backfocus ever so slightly but I don't use it that much and it was quite a good price on Ebay so I am prepared to wait until I buy either a cheap K20D or an expensive K-7.

Not sure Stefan, it just seems to work as long as you get this model. There is quite a long thread on Pentaxforums about Teleconverters and SDM, out of them all the Tamron is the only one that seems to work consistantly.

EDIT: LUCKY I NOTICED THAT SPELLING MISTAKE BEFORE MY 10 MINUTES EXPIRED

Yup, that's the version I have and its the only one that consistantly works with SDM.

No such thing as a bad macro lens.

Sigma 105mm
Tamron 90mm
Pentax 100mm

They will all do a good job.

Some strange looking critters there, especially like the first one.