The M42 17mm gets upgraded with SMC coating and mechanical coupling to allow open aperture metering with Spotmatic F, ES and ES II. It was produced from 1973 to 1976
Product Code: 43842
The slip-on cap is the 58mm one, the same one you can find on the first version of 28mm 3.5 M42 and on other Pentax lenses of the same age.
links
- Marco Cavina’s article on NOC sensei
- pentaxforums
- takumar.it
- if you don’t have the cap any more here is one on Thingiverse to 3D print.
