Dual Cable Release
by Richard Rylander

A dual cable release is an item that's pretty easy to build yourself, and very
inexpensive. The image above shows one I put together for about $10 (two $4.95
cable releases, a bit of angled aluminum, and a piece of plastic 1" x
1/2" x 1/4"). I would suggest you remove (unscrew completely) the time
exposure locking screws if the releases you use have them. "Dynamic
synchronization" is achieved by rocking your thumb until you begin to feel
resistance in both plungers. This kludge has worked well for me, never
"locked up", and the price and availability couldn't be beat.
Editor's Note: Another suggestion to refine the above
technique has been to remove the two thumb pieces and replace it with a single
piece of plexi-glass. This would be made easier by starting with cable
releases which have screwable thumb pieces. This is for vintage film
cameras with traditional mechanical releases.