Tamron Adaptall-2 SP 28-80mm f/3.5-4.2 (27A) - Sample Images

Info and Reviews:

Introduced: 1983 - 1987
Optical design: 9 elements in 8 groups
Lens mount: Tamron Adaptall-2, which is a interchangeable mount system. Can read more about it here: http://mattsclassiccameras.com/adaptall-2.html
Covers: Full-frame (24×36mm)

More info:

http://www.adaptall-2.com/lenses/27A.html

http://allphotolenses.com/lenses/item/c_671.html

Review:

http://www.pentaxforums.com/userreviews/tamron-adaptall-2-sp-28-80mm-f-3-5-4-2-27a.html