ARRI Forum

I want to swap the Alexa Classic's PL mount for something else (this has been done a lot before: C7 Adapters, Leitax, etc.) but do not know the flange distance of the sub mount on the Alexa Classic when the PL mount is removed so I am not sure how long to make the adapter.

Where can I get this information? Thanks.

Dear Policar,

before driving into schematics: PL Mount is 52mm. Subtract the mount from that and you have the distance that's left for your calculations.

Cheers,
Jan


EDIT: correction on the number

Thanks, Jan. I thought PL was 52mm? Or do you mean the PL mount part on the Alexa protrudes 2mm extra?

Sorrry, yes. I corrected it. My mind was going 52...44 (LPL).... 54mm is the diameter of the PL.

No worries, and thanks.

I'm finding it a bit hard to get an exact measurement because the black locking ring in the PL mount extends past the area where the back of the lens contacts the mount – so I can't get a precise measurement with calipers.

I've heard it's 20mm to 21mm but want to know what it is precisely so I can have a part machined.

Dear Matt,

if you're intestested in the drawings, please get in touch with [url=mailto:service@arri.de]ARRI Service[/url].

Cheers,
Jan

Thanks, Jan. I sent an email a bit earlier actually and I have the flange distance from Arri but, while talking with a few machinists, have realized it's a bit more complicated than one number. But I think we have what we need to move forward.

Great! Feel free to share the result if you fancy.

Cheers,
Jan

Thanks, Jan.

For anyone else interested, the submount flange distance (as illustrated in the attached graphic) is 20.983 mm.