as it is derivative of the Carl Zeiss Biotar optical formula.
It has a reputation for excellent build quality and with 8 blades it does beautiful bokeh, which makes her great for filming too.
Test video on Vimeo: https://www.youtube.com/watch?v=LXnTmYi_Crs
Maximum aperture: f/2
Minimum aperture: f/16
Lens serial number: 8184849
Auto and Manual mode
TESTED: yes, with Canon DSLR see pictures
CONDITION:
Cosmetic: very good
Optic: clear, no scratches, no fungus, wet tiny cleaning marks and tiny specks of dust
Focusing and Aperture Ring: work full range, smooth
Diaphragm: smooth
Mount: M42 easily adaptable to digital cameras
Comes with: no cups
The lens can be used on film cameras like Zenit, Praktica, early Pentax and anything else with a 42mm thread fixing.
The lens can also be used on various digital cameras like Pentax, Canon EOS, Sony NEX, Panasonic G and Olympus PEN series with PK adapters.
Focusing will be manually operated and metering will be operational in Av, P and M modes - some exposure compensation may be required.