At this time of year in northern latitudes, as the low angle of the rising sun comes later in the day and coincides with the rising of those of us lucky enough to have jobs to go to, projected images are everywhere. It makes you very aware of how photography must have been prefigured, in principle, for hundreds of years before anyone figured out how to do it.
Talking of optics and old masters, if you know the poem "Self Portrait in a Convex Mirror" by John Ashbery, and the painting by Parmigianino on which it is based, consider the poem's opening lines:
As Parmigianino did it, the right hand
Bigger than the head, thrust at the viewer
And swerving easily away, as though to protect
What it advertises. A few leaded panes, old beams,
Fur, pleated muslin, a coral ring run together
In a movement supporting the face, which swims
Toward and away like the hand
Except that it is in repose.
Now consider the painting:
Um, right hand?? It strikes me someone should have had a quiet word with Mr. Ashbery before the poem was published. Too late now.