Whats the Minimum Distance

[Luca Brazzi]

That the Fresnels should be from the LCD in order to not pick up the rings?

Would 1/4" for each fresnel in a split design do? As in 1/4" glass between each fresnel and the LCD?

 

[Gizmotech]

you need a gap of around 20mm between the collector fresnel and LCD.

 

[dave123]

I used 10mm = no rings