With the 3-trigger system

With a homemade trigger extra care is needed (the pin that is used in this install with 1GT101 is actually short, and unverified position).

Camhall trigger is optimally

If the camhall is +5V most of the time, a simple NPN-inverter can be installed (inside the box or outside). Please check the length and position of the +5V part of the camhall signal.