FREE is psuedo-zoom. It is pretty obvious if the focal length varies and it does. Pentax has made both dedicated and pseudo- zoom macros. I believe the switch occurred when they went from F4 designs to F2.8 designs in the early 80's. Of course any lens that "does" Macro is a "real" Macro lens but when I was referring to the "classic" macro lens designs I meant the fixed focal length designs optimized for a specific closeup magnification, similar to the designs of modern high end enlarging lenses. JCO
-----Original Message----- From: Kostas Kavoussanakis [mailto:[EMAIL PROTECTED] Sent: Tuesday, August 10, 2004 9:23 AM To: [EMAIL PROTECTED] Subject: RE: 50 or 100 mm > -----Original Message----- > From: Arnold Stark [mailto:[EMAIL PROTECTED] > Sent: Tuesday, August 10, 2004 9:01 AM > To: [EMAIL PROTECTED] > Subject: Re: 50 or 100 mm > > At 1:1 magnification, the F/FA100/f2.8 as well as the new DFA100/f2.8 > all are near 75mm lenses. You can see that from the working distance > which, at 1:1, is roughly four times the focal length. For the > FA/F100/f2.8, at 1:1, the working distance is 310 millimters, thus the > focal length at 1:1 is near 310mm/4=77,5mm. For the DFA100/f2.8, at > 1:1, > > the working distance is 300 millimters, thus the focal length at 1:1 > is near 300mm/4=75mm. The focal length of all these lenses varies due > to the FREE (fixed rear element extension) design. On Tue, 10 Aug 2004, J. C. O'Connell wrote: > We've covered this before but for closeup work I prefer the dedicated > classic macro designs over the pseudo-zoom types which are really > general purpose lenses. Is FREE pseudo-zoom? Are you saying that the prime Pentax macro lenses are not really macro? I rearranged Arnold's post so you can read it again. Kostas
