Originally posted by Miguel The question to you is how would you be using your macro lens? And are you talkin' about accurate macro (1:1) or vernacular macro a/k/a closeup?
I'm interested mainly in texture, in the way that 2D-seeming surfaces become three-dimensional when viewed extremely up close (rusted metal, or leaves for example). For that close-up as in "real close focusing lens" won't cut it, I need life-size, but I'm not trying to be scientific about a 1:1 reproduction ratio.
I used to shoot macro on film (with a 105) and want to get back into it, but it's not my primary focus, which is why I was looking for "dual-purpose" glass. Apart from the "cheap macro" route, I guess I could also see if I can get a good deal on a used MF lens as a dedicated macro solution ...
About the Sigma/Tamron: Interestingly, the prices for them here aren't that different, at least not when buying new: About 400€ for the Tamron, 450 for the Sigma, 500 for the Pentax. Good options nonetheless, and 100€ is 100€ ...
[edited for clarity]