Originally posted by TER-OR . . . For macro lenses, figure out what you want to do and look for the right lens. Used ones can be less expensive, of course. There are a lot of good choices available.
regarding costs and options for the different versions of the 100mm F2.8 Macro lenses
quoting from the In Depth Review of the D FA 100mm F2.8 Macro:
Pentax-D FA 100mm F2.8 WR Macro Review
Specifications
The lens covers the full 24x36mm format, not just APS-C. The aperture blades are rounded, delivering a smoother bokeh which is important for a macro lens. However, unlike its predecessor, it has no aperture ring.
The optical design is the tried-and-proven formula of the previous generation D FA 100mm F2.8 Macro lens, which in turn had inherited the optical design from the well-respected FA 100mm F2.8 and F 100mm F2.8 macro lenses introduced in 1991 and 1987, respectively. None of these earlier lenses had rounded aperture blades
Read more at:
Pentax-D FA 100mm F2.8 WR Macro Review - Specifications | PentaxForums.com Reviews