Why does Arri describe the Alexa as having a “35mm” PL lens mount?

[Gary Adcock]

[Chelsea Craig] “I understand what a PL lens mount is but why throw in the 35mm? It isn’t a film camera and it is describing the lens mount.”

Actually while the PL mount is an Arri invention (it stands for Positive Locking) there are other image sizes that also use that same mount.

35mm refers to the Super 35 (S35) film/ sensor size – making sure that you use glass that covers that sensor.

There are 16mm PL Lenses would be fine for the smaller size film and sensors (~ ⅔” of an inch) but cause vignetting or portholing where the lens does not cover the entire 35mm area.

There are some lenses designed for larger formats (70mm) that use other types of camera mounts like Panavision (PZ) even Hasselblad (Phantom 65)

gary adcock
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[Chelsea Craig]

Thank you for the informative answer!