there is a 1.5" dia cylinder bolted to the big plate that is held in with the 1/4-20 bolt
File: _MG_1314.JPG File size: 1,473KB Image Serial Number: 000-1314 Camera Model: Canon EOS 20D Firmware: Digital Photo Professional Date/Time: 2008:02:02 22:41:58 Shutter speed: 1/80 sec Aperture: 4.5 Exposure mode: Av Flash: Off ISO: 200 Focal length: 50mm Image size: 2937 x 2328 Rotation: none Color space: sRGB Color profile: sRGB v1.31 (Canon) User comments: "there is a 1.5" dia cylinder bolted to the big plate that is held in with the 1/4-20 bolt"
