The Edixa is more primitive than the Rolleiflex SL35.
For example the Edixa does not have an instant-return mirror. Also, the lens fitted to the camera has a spring-loaded semi-stop-down mechanism.
You cock the aperture open, then it closes and stays closed after the exposure.
To get a bright viewfinder again, one re-cocks the lens to open the aperture and cocks the shutter to bring the mirror down.
Lens mount is M42 and I believe instant-return aperture lenses will work as the camera body seems to have a standard aperture plunger.