Camcorder and C-Mount Lenses: Mount and Coverage

Mount and image circle: will it cover the sensor?

A lens has to match the camera's mount and also cover its sensor. C-mount lenses fit small-sensor cameras such as the Raspberry Pi High Quality Camera, and they are not interchangeable with CS-mount lenses without a spacer ring because the flange distance differs. Full-frame mirrorless or cine lenses cover bigger sensors, while a lens designed for a smaller image circle will show dark corners on a larger one. Check the listed compatible mount before the focal length.

Wide, standard or tele: focal length and attachments

Wide-angle lenses fit interiors and vlogs, standard lenses feel natural, and telephotos bring distant subjects closer. Cine-style lenses add geared focus rings and smooth aperture control for follow focus, while photo lenses are lighter. Lens attachments and converters change the view of an existing lens, but they add glass and can soften the edges. Step rings, such as 77 mm to 72 mm, join different thread sizes, and matte-box adapters hold the front end of a rig.

Questions about Camcorder and C-Mount Lenses: Mount and Coverage

What is the difference between C-mount and CS-mount?

Both use the same thread, but the lens-to-sensor distance differs by 5 mm. A C-mount lens works on a CS-mount camera with a 5 mm spacer ring, while a CS-mount lens cannot reach focus on a C-mount camera.

Can I use a full-frame lens on a smaller-sensor camera?

Usually yes if the mount matches or an adapter fits. The smaller sensor sees only the central part of the image, so the view looks narrower, by a crop factor that depends on the sensor size.

What are T-stops?

A T-stop measures the light a lens actually transmits, while an f-stop is calculated from geometry. Cine lenses use T-stops so exposure stays matched between lenses, which matters when cutting footage shot with different lenses together.