pan out

[Kingaroo]

Does this phrase come from gold mining or from film making or some other source?
I checked 3 word-lover web sites and don't see it

It's a synonym for "work out" as in:
That prospect didn't pan out
Let's wait and see how the week pans out
This use seems consistent with gold mining (stand in a river swishing gravel in a pan, hoping gravel will slosh out and gold will be left in the pan)


But I wonder if there's any connection with panning in film -- you would pull the camera back (out) to get a broader view and see the whole context of a scene....

[Quizmonster]

It's from gold-mining. The phrase 'pan out well' has been used in the figurative sense of 'work out satisfactorily' almost as long as it has been used literally to mean 'produce gold'.

[Skids]

Pan out in film means to zoom out to a panoramic shot.

[brachiopod]

I thought 'to pan' meant moving the camera about a vertical axis to produce a horizontal motion.

As in 'Pan and Tilt head' on a tripod.

Often used when following a moving object in a scene so that the object remains, say, in the centre of the shot; or to emphasise a great vista by slowly panning across the panorama and thus revealing it a bit at a time.

[Octavius]

Pan comes from the greek patane, which loosely means 'thing spread out'. 

In gold mining, it is simply called panning 

To pan out in general terms today means to 'turn out well' in cinematography it means to make a sweeping  movement

 

[Quizmonster]

The earliest recorded uses of 'pan out' in the figurative sense of just 'turn out well' date back to the 1860/70s. This predates any meaningful use of cinematographic techniques such as 'panning' by some time. Indeed, the very first recorded use of the word 'pan' in the filming sense did not appear until 1913, about half a century later.

So, the answer to your question, Kingaroo - which was effectively "Where does this phrase come from?" - is most assuredly "From gold-mining."