How to render only mirror and see objects only in reflection

[genesys]

How can I add a mirror to a scene and render only the mirror object, but still see the whole scene reflected in it (but only in the reflection, not otherwise)

[TomG]

Select the mirror and use "Render Selected' - while it renders only that object, it does correctly render shadows on the object, reflections and refractions in that object, etc.

[genesys]

Select the mirror and use "Render Selected' - while it renders only that object, it does correctly render shadows on the object, reflections and refractions in that object, etc.

I tried this, but this doesn't work. When only the mirror is selected I don't see any objects in its reflection. Only selected objects are visible in the reflection (but then they are visible in the primary rays as well)

[TomG]

Works just fine here - only the cube is selected, but the unselected spheres show up in its reflection: