Please ensure you have gone into Viewport Shading (top right) and enabled 'Camera' on the Compositing sub-menu.

The effects applied when using X-Monochrom all happen after the render has finished. The image will be rendered without any effects applied but, after the render has finished, the effects will be applied automatically and the image can be saved as normal.

X-Monochrom gives you fixed focal lengths to work with, similar to using prime lenses in real photography, and gives 3 presets for rendering. These are all built into the module for ease of use and fun, but there are no hard coded restrictions when using X-Monochrom. You can render at any resolution or aspect ratio, at any focal length you want if you so choose.

X-Monochrom packages Blender's standard camera up into a custom module which strips away most of the settings, encouraging composition and a 'photographic eye' over tweaking with settings. It also bakes in a custom curve to emulate the response of real black and white photography, rather than simply desaturating colors. You are given an exposure slider, ability to change f-stop and focal distance, and 6 fixed lenses to choose from.