1)There are several system cameras that will accept 2×3 Graflok style backs. I own many, perhaps most of them. Broadly (applies to most of this response):

a)2×3 Graphics (late 30s on)
b)Graflex XL
c)Mamiya Press with fixed G backs (includes the Super 23, albeit rare)
d)Mamiya Universal with G adapter (rare part, often pricey)
e)Mamiya RB67 with standard rotating adapter in several versions
f)Mamiya RZ67 with G adapter (rare part, often pricey)
g)Horseman technical cameras, as above
h)There are 4×5 -> 6×9 reducing backs. All have limitations, many shift the imaging plane.
i)It is possible that some 2×3 Graflex SLRs were converted. I do not know. I do know that my Super D 4×5 has what appears to be a factory installed Graflok back (and I do know factory installations were done).
j)Arca Swiss monorails (including reflex type)
…and there are others (e.g. Silvestri).

2) As far as rollfilm backs go:

a)Graflok 2? / RH?? in all their knob/lever/roller pin variations
b)Graflex backs. These will work as Grafloks, but will slide off to the side without a bit of a hack (you need to make an indexing ridge)
c)Early RB67 backs. Much more rounded than later models. Best balance of modern flatness and light tightness.
d)Late RB67 S/SD backs. Heavier, more interlocks. I believe I have an example of all RB67 back models except the two part motor backs (quite intentionally so).
e)Toyo/Horseman/Wista backs. Often have (removable) screw posts to hitch into the retaining arm.
f)Arca Swiss backs. Unlike the above, I don’t own any examples. Look very much like the Japanese backs without the posts.

In general, the younger the back, the more compatible. I’ve never had a camera not work with a Graflex (company, not back style) back. RB67 original backs are very much the same; I have everything but one of those on hand at the moment – but these are ideal for use on Press/Universals. When I find it, I’ll try it on my 970. If memory serves, they work. There are no hard and fast rules beyond that. I should make a chart.

3)A Horseman 980 (or any other, excluding the RF-less models) does have a way of providing focus distance. Assuming you are using a lens from the system (e.g. a Tokyo Kogaku 105/3.5) the matching focal length cam dropped in the bed will not only allow the RF system to work, but push a needle along a distance scale. Cams are a pain to find.

3.5) Failing that, I suppose a Vernier scale can be made. Um, good luck?

4)Lots of companies made RF coupled 6×9 technical cameras. Graphics, Technikas, B&J Watsons, Pressmans, etc.

Adam
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