Is this an Arri S or B mount?
Posted 09 January 2013 - 12:04 AM
Can anyone tell me by the pics in this auction if this is an Arri S or Arri B mount? Or is it even one of those or is the seller mistaken?
Posted 09 January 2013 - 12:57 AM
Posted 09 January 2013 - 01:44 PM
You can tell because of the two milled slots for the mount "ears".
As Dom notes, this is a low-end mount. The better ones have a nicer locking mechanism and can stay the camera as a new mount. This one seemingly uses setscrews to retain the lens, and is meant to be attached to the lens and left there.
This is OK so long as the screws either have soft tips or some sort of pressure pad underneath them, otherwise, a normal set screw (made of hard alloy) will leave a ding in the (relatively) soft stainless steel of the lens mount, and you obviously don't want that.
Although this adapter clearly allows for B mounts, many set-screw type adapters could also take an S mount lens since the throat diameter and backfocus were the same. It's a matter of whether the setscrews are placed to get a good grip on the flange groove.
Posted 09 January 2013 - 03:50 PM
This one seemingly uses setscrews to retain the lens, and is meant to be attached to the lens and left there.
There are a few cheap lens mount adapters to fit Arri mount lenses that literally fasten the adapter to the side of the Arri mount with set screws. A better kind has the screws at an angle so they apply pressure to the B mount tabs. At least it's better at assuring the lens is seated on the flange. The adapter Matthew pointed to on eBay, an Arri B mount lens is twisted untill you have a friction lock with the tabs. If one was switching out primes all day on an indie shoot the mount would stay in the camera and the set screw lock would not be used.
Obviously it's not as nice a design as the locking one at Whitehouse, but if its machined correctly for back focus and it's stainless then it could be usefull. It's a cheap price. The locking type may come up cheap on eBay if one is patient.
Posted 09 January 2013 - 06:54 PM