ATLAS 1.6x LF EXTENDER / EXPANDER PL to PL allows you to stop worrying about whether your anamorphic lens will cover a full-frame digital sensor. No vignetting. 
This extension allows you to expand the scope of application of lenses with cameras such as Arri Alexa LF, Sony Venice, RED Monstro, etc. 
Available only in combination with ATLAS lenses