I just completed installation of a Toyo 4X5 revolving back using the adapter plate now being sold from China on the big auction site. There was a thread on this subject recently but I feel some of the information was not quite accurate, so I will share my experience. First, this is not a project you want to attempt without some small machine tool experience, and no instructions are provided by the plate maker. Second, decide if you really want this mod after I describe the functionality.
The addition of the revolving back with the adapter plate adds about 3/8" of extension and will affect your ability to focus some very short lenses to infinity. The plate is designed to also fit the revolving back Graflex SLRS which have a square bellows. However, when fitted to a Graphic, which has a rectangular bellows, part of the 4X5 image would be lost if the back were turned vertical. A 6x9 roll film back may be used vertically with no problem.
The 90mm, 75mm and 65mm lenses all focus to infinity if mounted on the inner tracks with the bed dropped. No movement is possible with any of these lenses. A 47mm, which used to reach infinity on the old Graphic back cannot do so now with the Toyo mod. Most of my lenses for Toyo are mounted in Graphic lens boards and the idea of being able to to use Toyo back components on a hand-holdable, RF-coupled Crown or Speed Graphic is appealing. If a Toyo non-revolving back was used it might only add about 1/8" of extension.
You need to drill and tap the Toyo back for 4 4-40 screws (not supplied)which hold it to the plate.
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