I'll try:
35mm cameras and RED and other large sensor video cameras have shallow DOF because they use relatively long lenses. Long lenses are used because the frame is large. It is the focal length that mostly defines the DOF. Of course they do not project the image on a GG, but directly on the film or sensor!
In a 35mm adapter a large image is formed on a surface (spinning GG or wax plate) and reproed from that with a (too) small sensor video camera. This way we can use longer focal lenths to get shallow DOF on the GG, then copy that image on video. It is a clumsy workaround for something that happens naturally with large format cameras.
35mm cameras and RED and other large sensor video cameras have shallow DOF because they use relatively long lenses. Long lenses are used because the frame is large. It is the focal length that mostly defines the DOF. Of course they do not project the image on a GG, but directly on the film or sensor!
In a 35mm adapter a large image is formed on a surface (spinning GG or wax plate) and reproed from that with a (too) small sensor video camera. This way we can use longer focal lenths to get shallow DOF on the GG, then copy that image on video. It is a clumsy workaround for something that happens naturally with large format cameras.