I'm assuming you mean a Bronica SQ series. Seems to me that it might need an extra gizmo...
The other socket beside the threaded cable release socket is for the SCA 386 flash adapter. Buy this adapter and you will enjoy TTL-OTF (Off The Film plane) flash reading with Metz flashes. Sunpak and Quantum also make their own flash adapter compatible with their own line of flashes, which adds more flash versatility to the SQ-Ai system. The SCA 386 adapter is an expensive, puny little box with two coiled cords running out of it, one for the camera body and the other for the flash. The top of the box has an ISO dial that ranges from 25 to 1250 which means that if you're silly enough to shoot ISO 800 film outdoors and want one stop under fill flash, you're close but still SOL (**** Out of Luck). Users should also note that the flash exposure is independent of any metered prism exposure values so one has to ensure that the shutter speed doesn't go dangerously slow and show up hand shaking when in low ambient light conditions. No mention of Canon Speedlite there.
The above comes
from this site.