Really Right Stuff makes custom mounting plates for still cameras. Most of their base plates have a lip that prevents camera shift. This is critical when using a mechanical or powered follow focus system. Most HDSLR’s have a single 1/4 inch mounting screw. Really Right Stuff mounting plates solve this problem completely.
I ended up calling them a few times before I placed the order as the web site is a bit confusing. They only sell direct so make sure you are getting the correct parts for your camera. The “L” Plates are much more expensive than standard bottom plates. According to Carla over at Really Right Stuff each plate is made from a solid block, hence the added cost for the “L” plate.
I got mounting plates for the Canon 5D Mark II and Canon 7D. The B5D2 ( For The 5D MK II) and B7D (For The 7D) were each $55. The QR baseplate with lever was $120. Not Cheap, but worth the cost to keep the camera from shifting.