The 06A is rather uncommon, but when it does appear on the S/H market it's usually a lot cheaper than the 31A.
"This lens is an optical redesign of the earlier Adaptall model Z-500 and CZ-500 lens models. Its obvious, after comparing the optical designs of this lens to its predecessor, that Tamron's goal was to reduce the rather strong chromatic aberration and lateral color within the earlier optical design. Tamron's earlier Z-500 and CZ-500 models were unusual in that they were corrected for green and blue rather than red and yellow colors. This was preferable since most nature scenes predominately feature yellow and green colors, and since long distance telephoto photographs generally are affected by deep blue and UV haze. Nevertheless, the green-blue color correction in the earlier models resulted in significant amounts of red chromatic aberration and red lateral color. This significantly reduced the MTF for the earlier versions of this lens. Note that chromatic aberration and lateral color should be greatly reduced in this revised optical design, possibly making this lens an average to slightly above average optical performer within its class. Tamron's 200-500 F/6.9 model 06A lens was discontinued in 1984 with the introduction of Tamron's highly praised SP 200-500 F/5.6 model 31A lens." adaptall-2.com
Focal Length (mm) 200-500
Aperture Maximum 6.9
Aperture Range 6.9-32, AE
Field of View (24x36mm format) 12-5
Optical Construction (elements / groups) 14/8
Coatings BBAR Multi layer
Minimum Focus Distance (mm from film plane) 3000mm
Magnification Ratio
Filter Diameter (mm) 82
Length (mm at infinity) 370
Diameter (mm) 90
Weight (g) 2770
This lens does not have an "AE" position on the aperture ring, and has only one space for an auto aperture connection tab on the mount. It cannot be used in Av mode with a pentax PKA mount, or (probably) in auto mode with other mounts eg CFD.
Review by
Thomas Gade (google translate from German).