Originally posted by Peter Zack zeek10d, i don't know how you could list the lenses as you do since you stated "I went for Tamron as my 1st macro lens" without using the other 2.
When I was looking for my 1st macro lens, I went all over Singapore camera shops to test all 3 lenses and settled for Tamron. Like you all mentioned the lack of mm, also why my most used macro lens is the Vivitar S1 105mm.
Don't get me wrong, I'm no anti-Sigma. I know Sigma makes good lenses, I owned a few myself. But in terms of these 3 lenses go, the conclusion I'd got was the Tamron being the best value for money.
Tamron like Sigma makes good and bad lenses. Tamron 90mm Di happen to one of the best lens they made.
I'm a macro fan, I also understand they are all good lenses. If you were to give me all 3 lenses at once doing a same subject. In term of IQ, I'll say Pentax. But in terms of value for money. it's Tamron. The only reason I would had gotten a Sigma is for that few extra mm.
Edit: BTW I listed the lens not in any order, normally I'll add numbers in front if I want them to be in any order. e.g. 1.Pentax 2.Tamron 3.Sigma
As I mentioned they'll give all good result. Bokeh from my experience, Pentax is the best but Tamron is not far behind. I will not argue if anyone says Sigma 70mm or 150mm(I hoping for Pentax mount) better than Tamron 90mm, but not 105mm just lack the result of 70mm.