カメラレンズマウントの種類 – Cマウント、CSマウント、M12マウント（Sマウント）

Lens mounts are the mechanical interfaces that attach a lens to a camera and set the correct distance for focus.

Choosing the right mount is critical to ensure the lens can focus properly. Frequently asked first questions when building a camera is:

Will my CS Mount Lens work with my C Camera Mount?
Will my C Mount Lens work with my CS Camera Mount?
What is the difference between a S Mount lens and a M12 lens?
How can I use an M12 lens with a C / CS mount camera?

If you've wondered any of the above, you're in the right place! Below is a concise guide to lens mount compatibility. We'll compare C-mount vs CS-mount lenses and M12 vs C/CS-mount lenses – highlighting key differences, compatibility issues, and use cases.

CマウントとCSマウントの違いは何ですか？

CマウントとCSマウントのレンズ

C-mount and CS-mount are both common screw-threaded lens mounts used in machine vision and CCTV cameras. They share the same thread size (1-inch diameter, 32 threads per inch), but the flange height (formally called the flange focal distance, FFD) is different. The flange focal distance is the distance from the mount's shoulder to the camera's image sensor plane.

We believe the "S" in CS-mount means "Short" which explains why:

C-mount lenses have a standard flange height of 17.526mm.
CS-mount lenses have a 5mm shorter FFD of 12.526mm. The shorter back focus relaxes an optical design constraint, which lens designers can use for simpler, lower cost, or better corrected designs.

C-mount vs CS-mount compatibility is therefore one-way:

A C-mount lens can only reach focus on a CS-mount camera if a 5mm spacer ring is added.
A CS-mount lens on a C-mount camera cannot reach focus at infinity or at normal working distances. Physically the lens will thread on, but because the CS lens is designed for a shorter flange distance, it focuses the image in front of the sensor on a C-mount camera. Only very close objects can be brought into focus, so the pairing is impractical. There is no simple adapter to fix this because the lens would need to sit closer to the sensor than the C-mount flange allows.

M12レンズマウント、Cマウント、CSマウントのレンズの比較

M12 lenses (also known as S-mount lenses) are miniature lenses with a 12 mm diameter thread (M12 x 0.5). They are widely used in compact board cameras.

Comparing an M12 lens vs a C-mount lens (or CS-mount) reveals major differences in size and standardization:

Physical Size and Thread: M12 lenses are much smaller. They use a metric M12×0.5 thread instead of the 1″-32 UN thread of C/CS mounts. The entire lens is often only a few centimeters long. This compact size makes M12 lenses ideal for small embedded cameras, but it also means they typically work with smaller image sensors up to about 2/3″ sensor formats.

In contrast, C-mount lenses are larger and can support sensors up to around 1″ or more.

Flange Focal Distance: Unlike C/CS, the M12 mount does not have a standardized flange focal distance. The distance from the lens to the sensor in M12 systems depends on the specific lens design and the lens holder used. Each M12 lens must be matched with a compatible lens mount holder and adjusted (typically by screwing in/out) to focus on the sensor.

Not all M12 lenses are interchangeable across different holders or cameras – you must ensure the mechanical back focal length and lens barrel length suit your camera's mount. In other words, an M12 lens that works in one camera might not focus in another if the lens housing is different.

Mounting and Adaptability: M12 lenses screw into small lens holders on the camera board (often secured with glue or screws once focused). These holders are sometimes called S-mount or board-mount holders. Adapters do exist to use an M12 lens on a C-mount or CS-mount camera. However, compatibility is not guaranteed. In practice, if you attach an M12 lens with an adapter to a C-mount camera, it may not be able to focus to infinity or it might vignette since M12 lenses are designed for smaller sensors.

Always check the lens specifications and, if possible, test the combination before committing to an M12-vs-C/CS swap. In short, M12 vs C-mount/CS-mount lenses trade off flexibility for size and cost.

マシンビジョン用カメラとレンズの互換性一覧表

カメラマウント適合表

レンズの種類とマウントの種類を一致させることは、レンズを購入し、それがあなたのカメラに焦点を合わせることができないことを発見した場合、イライラすることがあります。このような問題に遭遇しているのはあなただけではありません！このレンズマウント互換性チャートをチェックして、誤ってカメラに互換性のないレンズを選んでしまったかどうかを判断しましょう。

For S-Mount or M12 Lenses, a mechanical comparison is needed between the lens, the lens mount, and the camera housing. The mechanical design for each M12 lens is different, as this mount type is not standardized.

Please note that this table assumes that your CS-mount or C-mount camera do not have artificial MBFL constraints. The Teledyne/FLIR/PointGrey Blackfly CS / C mount cameras are not compatible with all CS and C mount lenses unless the IR filter is removed.

M12/Sマウントレンズの焦点距離と直径は、CSマウントやCマウントのカメラと互換性がないことが多く、その結果、レンズとマウントの組み合わせでピントを合わせることができません。この非互換性は、他のM12レンズマウントでも発生する可能性があります。

In conclusion, understanding these lens mounts will help you pick the right lens for your project. For a large-sensor, high-precision vision system, go with a C-mount lens (or CS-mount if using a smaller format and tight space). For ultra-compact or camera modules, M12 lenses offer the smallest form factor at the lowest cost. And whenever mixing and matching mounts (like using adapters), double-check the focus and image quality to avoid surprises. With the proper mount, your lens can reach correct focus, and you can get the performance your lens and sensor combination was designed for.

M12レンズの検索はこちら

必要なカメラをお探しですか？

Use our free web-based AoV Calculator to determine your system's Field of View Requirements. Then, use the M12 Lens calculator to match your requirements with the available lenses. Our Depth of Field Calculator also provides the hyperfocal distance and depth of field for your sensor and lens combination.

また、多くのエンジニアが興味を持つような計算機もいくつかあります。

Lens Mount Holders and Adapters

Once you know which mount your camera uses, pair it with a matching board-mount lens holder or a C-mount to M12 adapter below. The full range, including M8 and M7 holders, IR cut switchers, and autofocus VCMs, is on the lens mount accessory page.