Thank you, Crux, for this suggestion. The link actually refers you to:
http://www.optcorp.com/pdf/Orion/Sta...SCOM100209.exe
to download this driver.
I have done this, but APT (Astro Photography Tool) can't find the camera, and the ASCOM dialogue implies that it is not connected (Properties button in the ASCOM Camera Chooser utility). However, after connecting the camera I had received a Windows message that the camera's driver had been successfully installed, and I can find it in Device Manager's list under USB devices. The Maxim DL Essentials application distributed with SSPro also has no trouble connecting to the camera, but presumably it is using the Windows driver, not the ASCOM driver.
Note: I have checked that the Microsoft .NET 3.5.1 is installed and enabled - a requisite for ASCOM 6.1SP1.
So, the problem seems to be with the ASCOM driver. Has anyone got any further suggestions? It's beginning to look like I'm stuck with using the Maxim DL application - a pity as APT is so easy to use.
Paul.