The 26A is one of Tamron's SP Adaptall lenses. Filter size 67mm. It is a push-pull zoom and is well made and heavy. It has a variable aperture range from f3.5-f22. It is f4.2 at 210mm. The aperture ring clicks at 3 times between f3.5 and f5.6 (f4, f4.5). It clicks at 1/2 stops from f5.6 to f16 then a full stop to f22. It has an AE setting beyond f22 but does not have a lock option. It has a 1:3.8 macro mode which can only be engaged at 35mm. To engage macro you must be at close focus. Look to the left of the scale and you will see two macro marking lines. They will be slightly misaligned. You must pull the zoom ring down and turn it to the right to shift the markers. To disengage macro you must pull down and turn to the left. There is zoom creep on my copy and I'm not surprised as the front section is quite heavy. Zoom dampening is typican of push- pulls. It slides well with a little hesitation here and there. The focus throw is a relatively short 1/3 of a turn. Precise focus can be tricky at wide apertures. Focus dampening is smooth and precise.

I've not had time to do significant, optical testing of this lens. However, first impressions are very good. At f5.6 it is sharp. I did notice a little fringing up to f5.6 that is easily correctable. Contrast appears excellent through the entire range and distortion is minimal at both ends. Color is neutral and accurate.