The Acratech 1138 Universal L Bracket does not provide access to the three buttons on the bottom of the Mamiya 6/7, as it covers the bottom plate entirely when mounted.

Yes, the Arcatech Universal L-Bracket is compatible with a Sony a7 III.

While it would depend on the design of the remote switch plug that you own. However, if the camera is placed toward the end of the bracket, there should be enough clearance for your remote switch to remain connected both in the horizontal and vertical orientations on your tripod head.

Yes this bracket can fit a D850 which already has an Arca type base plate attached to it.

The Acratech Universal "L" Bracket design is the sharp right angle.

Hi Robert, The correct Arca Style plate for the Canon 5D MKIV w/BG E20 is our part number 2164.

If you are referring to the base of the bracket being perfectly perpendicular to the arm of the bracket, then yes, it is perfectly square. The L-bracket is precision cut using a C.N.C. machine for accuracy purposes. While B&H does not open new products to ensure they are sold in the condition in which they were received by the manufacturer and we do not perform product testing on items before shipment to customers, if you receive the item and you are unhappy with the item's performance for any reason, do note you would be able to return or exchange the unit during our standard Return Policy period.https://bhpho.to/2bxrYlG

Yes Acratech Universal "L" Bracket is compatible with the Sony A7iv and the Sony A7rv if you have an arca type plate attached to the camera.