JammyJamSam

BTW trying to avoid the method of blackening the edges of the two front lens elements, if possible.

Will a lens hood help with the white halo-ish, reverse vignette issue? If so, is a special lens hood required due to the wider FOV at any given focal length vs a spherical lens? 

For context, I am running a SLR Magic Rangefinder Cine Adapter + Sankor 16F + Helios 44-2 + Metabones Speedbooster 0.71x + BMPCC4k set up and get a very strong white oval around my frame when a strong light source hits the lens.