Thanks for all the help. It is starting to come together, and I suspect now that all I'm missing is the serial cable that runs from the Sinarcam to the Mac.
I'll describe what I've found in some detail: After looking at all the pictures/diagrams, what was described to me as the expolux is actually the auto-aperture controller, which looks similar but with less extension at the top .. and obviously with no shutter. Then there is what I believe to be a Sinarcam 1, which is the one designed to work with the Leaf DCB II Live back. (Apparently the Sinarcam 2 works with the Sinarback, and the Sinarcam 3 with another back, so the 1,2,3 designations were not so much revisions as versions of essentially the same camera - does this sound accurate?) In this case, the Sinarcam contains both the filter wheel and the shutter, and both of these are controlled from the Mac via this missing serial cable. So then the cabling I have starts to make sense:
1. The Leaf back: There is a dedicated power supply with one cable running to the back, and a shutter release, which are the only visible connections into it. The connection between the back and the Sinarcam is via 2 sets of 6 contacts on the interface between the two. Mechanically the Leaf back mounts directly onto the Sinarcam.
2. The Sinarcam: has one visible input, which runs from the RS232 Expolux power supply, and a similar looking output, which connects forward to the auto-aperture controller. Both of these cables are designated 522.21.021.
3. The Expolux RS-232 power supply: This is turning out to be the brains behind everything. At the moment I have just one cable, which loops out of the RS-232 power supply, essentially through a dedicated card on the mac, and then connects to the Sinarback, and then out of the Sinarback to the aperture controller.
So [RS-232] ----- [PowerMac 9600] ---------------- [Sinarback] ----- [Aperture controller].
The first cable here is one piece, what I described before as a Y-cable. All connectors so far are flat SCSI-like clip in connectors. From what I can tell, the cabling above powers all the devices and gets image data back to the Mac.
What is missing then is another serial cable to connect between the Expolux power supply and the Mac, from a DB9 connector to a RS422 connector on the old PowerMac 9600 I'm using for this. This cable seems almost impossible to find.
So, referencing Rick Adshead's comments (thanks!) I seem to have this situation:
"Lets assume that you have a real Sinarcam and not an Expolux shutter. In this case you should get LC 7.0 which will support DCB 2 and will provide direct support for the shutter. The power supply for this Sinarcam might say “Expolux” but a real Sinarcam 1 will be contolled directly from the Leaf SW. A serial cable between the Sincarcam and the Mac’s serial port provided this connection and is required."
So I need:
1. The serial cable (DB9 connector -> RS422 mini-DIN connector)
2. Leaf Capture 7 (I currently only have LC 5, which was installed when I bought the system. It does seem to have controls for setting shutter speed, but of course without the cable I can't test this yet)
If anyone can point me in the direction of either of these, it would be much appreciated!
Thanks again for all the help.
Andrew