Try it yourself and then comment. I've done it and the differences don't seem to be that great - hardly noticeable at all in some situations, not at all in others. Camera was mounted on a Pentax macro copy stand, same camera used, same film, and a refconverter used @ 2X to check focusing accuracy.
While there may be some differences that become obvious at some point, they were not obvious in a 5x7 print. I don't think the 100/2.8 macro in any way "crushed" the K105/2.8 when the subject was a three dimensional object. Results may be substantially different when photographing a two dimensional object. Shel > [Original Message] > From: J. C. O'Connell <[EMAIL PROTECTED]> > In the close up range shorter than what the 105 mm normally > focuses to (i.e. resorting to put tubes on the 105mm) I would > expect the 100mm Macro to absolutely crush the 105 performance.
