Originally posted by northcoastgreg I believe it is the K series lens that is identical to the takumar. The M series has a different design.
While the K series short telephotos tend to be sharper than their M series counterparts, I'm not sure whether that is so in the specific instance of the K and M 135/3.5s.
Yes, it is indeed the "K" 135/3.5 which is identical to the SuperTak (apart from the coatings) - BUT only if the SuperTak in question is the "Mk2" version...
I'll explain: the SuperTak first appeared in the early 60s, had single-coating and 5 elements in 4 groups. A few years on and the design was changed to 4 elements in 4 groups. A few more years, and the same optical design became the S-M-C Tak, which had multi-coating.
Then came the K-mount and SMC designation. The first of these was optically identical to the S-M-C Tak, and is known as the "K" 135/3.5. This was replaced a couple of years later by the M 135/3.5. This was an entirely different optical design, with 6 elements in 6 groups. It was notable for its small size.
Now for how they compare: obviously, the multi-coated versions have superior flare resistance, and probably contrast. I have both the "Mk1" SuperTak and S-M-C Tak. I find my SuperTak (distinguishable from the "Mk2" version by the presence of a "4" - i.e. f4 - marking on the aperture ring) to be softer than any of my other 135s. This may or may not be true of other examples of this lens, but I personally would steer clear of the "Mk1".
Both my S-M-C Tak and "K" are nice sharp lenses - even wide open. My M 135/3.5 is probably not as sharp, but tends to be preferred because it's so beautifully compact (but then I
do like small lenses!).
As has been pointed out before in this forum, many (but not all) lenses of this era will show colour fringing, and the Taks/Pentaxes are no exception. (I believe the consensus is that the German and Soviet lens are superior in this respect.)
So, from the OP's list of alternatives, I would be tempted to go for the SuperTak IF (and only IF) it doesn't have an f4 marking on the aperture ring. This assumes that sharpness is the ultimate priority, but if size and convenience are important, I would suggest the M.