Originally posted by Precious I am wondering, if it's worth it to buy Pentax 100mm 2.8 macro WR lens ?
In absolute terms, yes, it's a lens that is worth its price.
Originally posted by Precious For my macro photography I use Sigma17-70mm f/2.8-4 DC Macro OS. I know it's not real macro (1:2), but it's quite good.. Will I feel big difference between them? Has anyone used these lens for macro before?
I own the previous version of the Sigma and the DFA 100 WR. If you like to photogrpah smallish subjects, like a whole flower, the Sigma works very well. If you want to make real macro, then of course you need an actual macro lens, there are technical things that only a macro can do. The enlargment given by a true macro lens is hard to understand until you test it.
I personally wrote the reviews of those two lenses that are presented on this site, you might want to check them. They should help you decide wether or not to get the lenses.