> After "tinker[ing] with different combinations of lenses and film stock," the production obtained three super-fast 50mm lenses (Carl Zeiss Planar 50mm f/0.7) developed by Zeiss for use by NASA in the Apollo Moon landings, which Kubrick had discovered. These super-fast lenses "with their huge aperture (the film actually features the lowest f-stop in film history) and fixed focal length" were problematic to mount, and were extensively modified into three versions by Cinema Products Corp. for Kubrick to gain a wider angle of view, with input from optics expert Richard Vetter of Todd-AO. The rear element of the lens had to be 2.5 mm away from the film plane, requiring special modification to the rotating camera shutter.
> After "tinker[ing] with different combinations of lenses and film stock," the production obtained three super-fast 50mm lenses (Carl Zeiss Planar 50mm f/0.7) developed by Zeiss for use by NASA in the Apollo Moon landings, which Kubrick had discovered. These super-fast lenses "with their huge aperture (the film actually features the lowest f-stop in film history) and fixed focal length" were problematic to mount, and were extensively modified into three versions by Cinema Products Corp. for Kubrick to gain a wider angle of view, with input from optics expert Richard Vetter of Todd-AO. The rear element of the lens had to be 2.5 mm away from the film plane, requiring special modification to the rotating camera shutter.
https://en.wikipedia.org/wiki/Barry_Lyndon
> The lens was designed and made specifically for the NASA Apollo lunar program to capture the far side of the Moon in 1966.
> In total there were only 10 lenses made. One was kept by Carl Zeiss, six were sold to NASA, and three were sold to Kubrick.
https://en.wikipedia.org/wiki/Carl_Zeiss_Planar_50mm_f/0.7