To get the best from a spotter it helps to compare the glass lens diameters of the type of lens you will use. CCTV zoom lenses generally have 11mm diameter rear glass elements. 'C' mount lenses that are better for our purposes generally have 16mm diameter rear glass elements. So we need a proportionally larger hole through a fitting adaptor to get the best out of them.
The bonus with this type of adaptor is massive because the whole of the wider (16mm) C mount rear glass lens views the whole of the CCD sensor edges through a 16mm 'apeture' rather than the cheaper ebay types that screw into the M12 threaded camera neck with a tiny 10.5 mm hole through them that is designed to suit the small rear glass element of the zoom type CCTV lens. The Ebay one's therefore obstruct some of the edge detail from the exit pupil of a 'C' mount lens on its way to the camera sensor.
My E700/C mount lens camera carriers also have four M4 threaded fixing holes to solidly fix the lens and camera assmbly to your panel.
They are designed to reliably and robustly fix a C mount lens to a panel or box, then use the 16mm diameter neck of any metal cased camera to accurately centre and glue it into the rear of it using silicone bathroom sealant on the metal case. Note the camera body, being inside a protective box is not subject to the occasional handling knocks that the external lens would get, and the sealant sticks like shit to a blanket.
Notice the O-ring around the neck of the carriers?
Now look close to see the gap between the top of the lens carrier and the box of my mag mount spotter is wider than at the bottom, and the lens is tilted slightly lower than the torch? The O-ring allows the adaptor to be tilted by adjusting the tension of the fixing screws so the camera and lens views slightly lower than where a fixed torch beam is centered at: We don't need much light in the foreground, so getting the light beam's hot spot higher in the monitor lights up the distance better, partly because the foreground brightness would otherwise be shuttered out by the camera, which shuts down the distance performance too. We can avoid that by aiming the torch high - or the camera and lens lower.