There are various types of monoculars.
Some have removable eyepiece lenses, while others cannot.

 

■If the eyepiece lens cannot be removed
When the eyepiece diameter is φ30mm to φ32mm and made of hard material such as resin

 

 

You can attach a camera by connecting an adapter lens like the one below to the eyepiece part.。

 

 

	可変倍率カメラアダプタレンズ BA-A1835
	カメラアダプタレンズ BA-A35

 

■When the eyepiece lens can be removed
When the inner diameter of the straight cylinder after removing the eyepiece is 23.2 mm (JIS standard)

 

 

You can connect a C-mount camera by removing the eyepiece and inserting a relay lens in its place as shown below.