Any mechanical cable release that screws into the shutter button should work as a shutter release.
You could also buy a genuine CANON CABLE RELEASE 50 on eBay or elsewhere.
If you are using the camera with a power winder or motor drive, they will have a 2.5mm plugin electrical connection that will also work for you. Canon calls these 2.5mm cables Remote Switch 60 or Remote Switch 3.
