I am trying to capture DV or HDV from a Sony camera via the Firewire 800 input on my iMac, but Avid M C can't see the divice or any ports. The system can see the camera as it is possible to capture in iMovie. Any ideas ?

Check the camera menus.  Sony cameras and decks use the I link port as IEEE 1394 for deck control.  The interface may not be set correctly.  Also make sure you've set the deck configuaration to firewire on OHCI.  Do a search on the knowledge base for supported devices.  This PDF is updated frequently and lists all cameras and decks tested by Avid engineering and gives instructions on specific menus settings as needed

HTH                                                                                                                                                                                   

Thanks.  I've tried all the possible camera menus but no joy. The camera (Sony FX1E) is present and correct on the firewire bus in the iMac system profile.  Could the fact that it is a firewire 800 bus (rather than 400) be a problem ?

Sorted. Uninatalled ALL Avid elements (Not just media composer) and reinstalled.

IEEE 1394 now present in the 'Special - Device' menu and capture works.

I think the problem may have been due to a previous attempt to install Avid Xpress pro on the iMac.