Externally, my Monocle looks like an Olympus M.Zuiko Digital 14-42 mm.
The exterior has not changed, everything remains as before. I removed all the lenses except the front one and left the diaphragm mechanism. The aperture allows you to change the image pattern.
Light halos are obtained due to the gaps between the diaphragm mechanism and the lens body. At one time, I eliminated this "defect", but the photo became less expressive, it became "like all" monocles.

I like to play with these halos. Depending on the location of the light source, its intensity and other features, you can get different interesting effects.