The lens “Yashica Contax Carl Zeiss Sonnar 135/2.8” was released in 1985.
It is a manual old lens, and it is compatible with the image circle of a full-size sensor.
When this lens is used with Micro Four Thirds (MFT), it becomes a telephoto lens with a 35mm equivalent of 270mm. This is interesting because it takes good pictures.
Olympus' in-body image stabilization is so powerful that hand-held shooting is also possible.
It is also very light for a 270mm f/2.8 lens.