1. the newest one is the OS version which is simply an amazing lens. I own the HSM II version and its about 95% of the performance you get from the OS version, but still a really good lens. The non HSM should be pretty similar in performance from what i've read online.
The non-HSM version actually focuses faster. Look it up on youtube, the focusing speed on it is just crazy.
2. no, fast focusing is even more important in film IMO since you get no second chances with film
3. the HSM based models wont work, the screw drive version will
there's a in-depth review on the site comparing the newest sigma, the tamron and the pentax
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