Question on Pentax SMC-F 28-80mm

[Joe Wilensky]

Does anyone know why the SMC-F 28-80 f/3.5-4.5 zoom, which seems to  
have a really good reputation (at least compared to the 28-80 powerzoom  
that replaced it and compared to other A- and F-series Pentax 28-80 &  
35-80 zooms) is so hard to find? Most SF1/SF1n and SFX/SFXn cameras on  
eBay seem to be listed with the cheaper, non SMC Pentax-F or Takumar-F  
versions of this lens. See:  
<http://www.bdimitrov.de/kmp/lenses/zooms/_non-SMC/pen-F_28-80f3.5 
-4.5.html> and  
<http://www.bdimitrov.de/kmp/lenses/zooms/_non-SMC/tak-F_28-80f3.5 
-4.5.html>.

I would have thought that as the top-of-the-line Pentax cameras at the  
time, the 28-80 zoom that would most often be found with these cameras  
would be the SMC version  
<http://www.bdimitrov.de/kmp/lenses/zooms/short/F28-80f3.5-4.5.html>.

I finally found one on eBay -- see  
<http://cgi.ebay.com/ws/eBayISAPI.dll? 
ViewItem&item=3817448223&ssPageName=STRK:MEWN:IT> after I bought one  
from KEH that was erroneously listed as the SMC version. The one that  
showed up from KEH was one of the many Pentax-F ones they have listed.

Does anyone have this lens or remember why the cheaper versions were so  
prevalent at the time?

Joe