I played with some measurements myself, before noticing Detlev's image. After figuring the farthest point on the camera from its optical axis is the outside bottom corner of the handle grip, that seems to be about 135mm from optical center. Currently it seems the R90 rig's radius is about 116mm. So the circle it is based on would have to grow about 17% Not that much. I guess that would make the whole circular arc portion of the rig grow by close to 25% though.
Another thing. What if the side handle grip were removed and a different mounting bracket for the camera brain were used? Seems the R90 rig would accommodate that configuration and allow for rotation around the optical axis...
All that thinking aside, I agree with Jarred's statement above that optical axis rotation is not really necessary. However, just thinking of a few cool tricks that can be done if maintaining the optical axis is possible.
Eitehr way, I'll have to be buying the R90. It looks 100 times better than the chunk of aluminum angle I use now. :)




Peter