Tamron Adapt-A-Matic 21mm F/4.5 Model PFJ-45Au: This lens was available in three versions. We are not sure if the PFJ-45Au model name applies to all three versions. Initially there was the first model which featured a relatively large optical layout and a metal knurled focus ring. Then there was a subsequent model which featured a rubber focus ring yet still did not have slots on the aperture ring for the aperture coupling band included with later versions of some Adapt-A-Matic mounts. The final version of this lens features a rubber focus grip plus the slots for aperture coupling bands.

Lens Specifications:

Lens Model	PFJ-45Au
Focal Length	21mm
Aperture Range	f/4.5 — 16
Angle of View	91°
Optical Construction (Groups / Elements)	6 / 8
Min. Focus from Film Plane	9.8" (0.25m)
Macro Mag. Ratio	—
Filter Size	17mm (rear), 82mm (front)
Diameter	3.3" (84mm)
Length at [w/Nikon mount]	[2.2" (55mm)]
Weight	11.7 oz. (332g)
Lens Hood	?
Accessory	—