Hello Greg, All I can say is that I used to own the FA 100/2.8 macro and at this point own the Tamron SP 90/2.8 macro. I don't see any real difference in image quality between them. I have heard that the FA 100/2.8 Macro does have some issues with the *istD and CA, but have no direct experience with it. I am more than happy with the Tamron and would probably buy it again over the Pentax if given the opportunity. It is not much cheaper either - at the time of purchase, I believe it was about $30-40 cheaper.
-- Best regards, Bruce Monday, January 24, 2005, 9:41:06 PM, you wrote: GL> How does the old K/M/A 100/4.0 Macro compare optically to the F/FA 100/2.8 GL> Macro? GL> From http://www.pbase.com/steephill/image/38667710, it looks like the 2.8 GL> resolves more detail. What about other factors? GL> I've read either here or on DPReview or both that Pentax macros are better GL> than the best 3rd-party macros, including the Tamron 90 and the Sigma 105. GL> What about the K/M/A 100/4.0 Macro -- is it also better than the Tamron 90 GL> and the Sigma 105? GL> Also, I'm surprised at how much smaller and lighter the new D FA 100/2.8 GL> is compared to its FA predecessor. Does it sacrifice image quality GL> compared to the FA? GL> Thanks, GL> Greg
