Well, yes. I was a bit nonplussed by the second screen. He could have mounted them both on the lens side.
Just a single stronger Fresnel on the rear would suffice, there's no need for two.
As far as I can tell from his comments, poorer definition is what he's after and it's what he gets. If he's using the images online, they're probably entirely satisfactory.
I welcome this sort of experiment. Makes a change. Who knows what may come of it?
I had this conversation with someone a few days ago, he worked for the highest end lens manufacturers until retiring last year, it's the terrible US term Bokeh, it's too loose a term.
Essentially the typical aim is usually very shallow DOF, swirly Bokeh in out of focus areas, but reasonably good sharpness
I think this video project is aimed down market, it really only works because the final images shown are actually reductions of the projected image.
What would a centre-filter for an iPhone cost?
An arm and a leg with the nanotechnology required to make one so small. However, it's the Epidiascope that would benefit most from the centre filter. But ingenious alternatives have been used in the past, like the fan blades of the Goerz Hypergon.
I'm having a major clear-out, and there are projection lenses, of different designs. I'm also testing my recently acquired Quick Acting Dallmeyer Portrait Petzval an 8" f4 lens, as well as an unbranded 8" f5.6 Petzval, a TT&H 16" f8 12"x10" RR, and an unbranded 20" f8 RR.
Ian