Strange flares on the Iscorama

[au8ust]

Not sure when it started to have these wired flare at corners. Anyone knows why and how to fix that? It appears with every lens I tried. The glass looks clean though.

[nahua]

These are commonly referred to as rainbow flares.  They are part of the character of an Iscorama and other anamorphic lenses.  Usually depends on the taking lens, and it shows up with single or non-coated lenses.  Not sure why you'd want to remove it, and the only way is to not shine a light at the lens or basically not have any flares at all.  Otherwise I advise you to get an Isco Ultra-star anamorphic projector lens or some modern multicoated lens (MC).  Then you won't get any flares but have the anamorphic stretch.

[au8ust]

Thanks Nahua for the input!

This is actually the Original Iscorama. I don't recall exactly when it started having the rainbow flares but I somehow recall it wasn't there when I tested it long time ago.

My Iscorama Cinegon doesn't have these rainbow flares at all so that made me wondering why it happens. Tito told me it was from the original Iscorama's design. I'm still not sure though.

[Cineman1]

See if the unusual light marks change as you stop down.  Could it be bright light reflecting off the edge of the iris blades?  Do the shape of the marks roughly approximate the blades of your aperture?  Maybe it's from a specular source reflecting off the hand cut (and somewhat imperfect) bevelled edge of the rear anamorphot element?