Those who still have the (huge) converging Fresnel lens called BEAMSCOPE (a transparent rectangular placard made of Plexiglass or Perspex, to place in front of a television screen to make it look "larger"), could use it to observe, what is known as, schlieren optics in Earth's turbulent atmosphere between the BEAMSCOPE and Sirius (the brightest star in the sky). Try to hold your BEAMSCOPE at arm's length (with both hands of course) and bring the focus of Sirius on one of your two eyes. You shall see the whole surface of this Fresnel lens "lit up" (not very bright, but... noticeable). Depending from where on Earth you look at it, and at what angle above the horizon Sirius is seen, there will almost always be the effect of Earth's atmospheric turbulence, appearing as an equivalent of the phenomenon known by some as the "flying shadow bands" shortly before and shortly after a Total Solar Eclipse.
Of course, this optical experiment could also be performed with Venus, or a distant bright artificial pointlike lightsource near or at the horizon.
P.S.: I want to talk about such topics with my colleagues on the workfloor, but they look at me with EYES... (what the hell is he talking about ?!?!).

See also (WIKIPEDIA) - Schlieren photography, Fresnel lens.
Edited ...
Like