The Mir 37mm is a macro wide angle, branching into medium lens territory. It also has a very long focus pull, but it measures much faster than the standard 37mm f2.8. Turning the focus ring of this lens pulls the focus timing much faster. Being that it is a macro, it can focus on very small objects.
This lens has a native Pentax M42 mount, but has an EF adapter added. This lens covers full frame, Super 35mm and Micro 4/3.