Scaling down Zooms in (as with shrinking your camera in real life :-)

 

Yep. It's not focal but, on rethinking this you can use the lights focal dials while watching through the light camera. This is what I hoped to say.

To be clear,   right click workwindow, select correct shadowcam. Then left click the centermost light on lightball icon. This should swap parameter box to your camera's light.

Now you can tune your light and slave your camera to your actions. Changing your light's focal should now have a realtime effect in preview. Also aligning your subject matter to realtime light and shadow.

 

Writing from memory. I know you guys know this. Just being clear(er) for casual readers.