Nothing, actually. There's no open shutter function nor is there a spot to thread on a shutter release (for a press camera or something?). Therefore the solution we came up with in HS was to glue onto the lensboard a threaded shutter release adapter that hits the shutter arm. Effectively, we thread a locking cable release into that adapter, cock the shutter, open and lock it. Kinda ghetto, but it has worked for about 8 years or so. Now that the new camera doesn't take the same lensboard, I realized I won't be able to use the same technique, unless of course I want to glue it on that one as well.