There is a second type of setting ring that lives inside the hood or filter next to lens to adjust aperture back off clamp screw and rotate filter or hood then tighten screw.
Originally Posted by John Koehrer
Invention of devil and the rings are collectible...
If you want photos the modern post 94 Elmar is comparable with late post 79 cron.
it us well compact collapsed with hood in place.
But a LTM Cosina /2.5 is only 1.5mm larger with hood.
And you don't need to extend or collapse.
Both have good ergonomics you won't tell the pics apart on 10x8s...