Brandon is right.
At NAB, I took a flashlight right into the Zeiss Concept Anamorphic 50mm Lens and could not get any flares.
The design is too perfect. Also, the Zeiss product development person for the anamorphic lenses was looking for input
and was uncertain at the time as to what focal lengths where to be first released.
As perfect as Zeiss claimed the concept lens to be not having flare ability, it did look much more cinematic with the Alexa when side by side shown on monitors
with an Alexa using a new Fujinon/ARRI Lightweight Zoom lens.