Player One 2.1mm CS lens

This lens is designed for cameras that use the CS-mount standard. This includes many dedicated all-sky cameras, security and surveillance cameras, and some specific astronomical guide cameras. It is not compatible with C-mount cameras, whose longer 17.526mm flange distance keeps a CS lens from reaching focus, nor will it work with DSLR or mirrorless cameras.

The field of view depends entirely on the size of the camera sensor you pair it with. The lens projects a circular image; a smaller sensor captures a smaller portion of that circle, while a larger sensor captures more of it.

• On a 1/3" sensor: The field of view is 150°.
• On a 1/2" sensor: Player One does not publish a figure.

Yes, this is an ideal application. For maximum sky coverage to capture meteor showers like the Perseids or Geminids, pair the 2.1mm lens with a 1/3" format camera such as a Player One Mars series model, which gives a 150° field of view covering a large patch of sky.

While technically possible, it is not recommended for precise guiding. The extremely short 2.1mm focal length results in a very low image scale (many arcseconds per pixel), making it difficult for guiding software to detect the small star movements needed for accurate corrections on a long focal length telescope. It is designed for imaging the entire sky, not for high-magnification guiding.

The lens is focused with its own focus ring, marked ∞ to N on the barrel. Once focus is achieved for infinity, it is often locked in place for dedicated applications like all-sky monitoring.

It takes in a large part of it. On a 1/3" format camera the lens covers a 150° field, enough for a long stretch of the Milky Way in a single shot. This makes it excellent for dramatic, wide-field astrophotography and time-lapses.