View Full Version : Toyo 45AX extension back

Ralph Barker
28-Aug-2008, 19:44
Not wanting to pay the price of a Toyo extension back, I decided to make my own:


The fact that Toyo uses the same physical interface for various components (lens boards, backs, monorail standards and bellows) made it fairly easy to construct around that standard.

28-Aug-2008, 19:58
That looks pretty nice--what kind of wood did you use?

Ralph Barker
28-Aug-2008, 22:17
It's a prototype, so I just used some inexpensive spruce I had on hand. If I like the way it works, I'll make a "real" one out of cherry or walnut.

Christopher Hansen
28-Aug-2008, 22:21
Did you need any metal parts or did you just cut slots in the wood to attach to the camera?

Ralph Barker
29-Aug-2008, 09:46
Did you need any metal parts or did you just cut slots in the wood to attach to the camera?

I cut out the center of two 158mm lens boards and attached them to either end of the box (constructed with through dovetails for strength). The little lip on the lens boards provides the interface to the camera body.


The center portion of a used standard from a Toyo monorail (about $60 from an online vendor) functions essentially as a "gender changer" to attach the film-holder back to the extension. Mini mortises were cut in the ends of the extension box prior to attaching the cut-out lens boards to accommodate the slider-bar retainers and protrusions on the lens boards. Using this approach, I figured I could make other extensions of different sizes if I wanted to later, and the one "gender changer" would work on all of them.


I started with 3/4" stock, cut the dovetails, and then trimmed the thickness down to about 1/2", as the box segments need to be thick enough for the screws used to attach the cut-out lensboards. I used 6 screws per side for maximum strength and flatness. A small bead of black silicon caulking/gasket material provides a light seal between the box end and the cut-out lens boards.

Gene McCluney
29-Aug-2008, 10:05
Thats great. I have a Rittrek 5x7 field camera that has factory whole plate, and 8x10 extension backs. It is an ingenious way to make a camera more useful. You could also, make a 5x7 back with appropriate parts from an old wood 5x7 salvage camera.