This is the best macro out there. Period. I've tested against the Voigtlander 125mm macro, and it had the same sharpness wide-open. And I actually found that the bokeh was a bit smoother than the Voigtlander (just a tiny bit).

I also had the Leica APO 100/2.8 (another legend). And though I didn't test them against each other, I would say this lens is also in the same league. The only macro that I've not tested is the Zeiss Makro 100/2.8 Planar, even though some people would say this lens is inferior to the Leica. And that's why it's the best, since it costs only a fraction of any of the above macros with comparable IQ.

So how is this lens compared to the Vivitar S1/Kiron/Lester Dine 105mm macro? Well, it's just plain sharper. I've done a comparison here on Pentaxforums to show this. And there is another guy did the same test (in case you don't believe me):

Making Not Taking: 105mm Kiron Iterations

To quote him:

"For the sake of argument, I actually do own a lens that is sharper wide open than these 105's. My favorite Vivitar Series 1 90mm f/2.5. Interestingly enough, these lenses tend to go for a considerable amount less than any of the 105mm version lenses, despite being sharper."

Well, I don't have the matching 1:1 macro extender, but you can find the matching macro extender at very low price. In fact, it just happens there is a Vivitar Series 1 macro adapter on eBay right now for PK mount for Pentax shooters:

Vivatar Series 1 90 mm f2.5 macro adapter - eBay (item 170518756172 end time Aug-01-10 08:23:48 PDT)

And this lens is in M42 mount, so a simple adapter M42 to (insert your mount here) would be sufficient to use directly on the camera or with the extender.

Optically, there is no scratch, fungus, haze, or any imperfection. The only thing that would prevent this from being perfect is dust speck, which would not affect the IQ at all. Mechanically, this lens is in perfect working order with smooth focusing feel. Cosmetically, I've to say this is near "Like-New" condition. There is no brassing, no mark whatsoever on the body. The cap is in mint condition, but you might be able to tell it that it's not new.

I already have one in FD mount to play with on my E-PL1, so this one has to go. I'm asking $400 shipped and paypalled Gift (+3% fee if you want).

A few pictures taken with this lens: