Safest way to trigger camera shutter using arduino

Question

I'm working on a prototype where I'm controlling my DSLR using BLE module.

I found many tutorials to trigger shutter release using Arduino on the internet.

So far, I have found optocoupler to be the safest option.

Is there any Better than optocoupler ?

How does original intervalometers/remotes for Canon & Nikon work ? Even they use optocouplers ?

As I'm planning to release my prototype in the near future as product, I don't want to endup damaging users cameras.

Note : My board works on 3.0 V

Answer 1

Optocouplers can provide galvanic isolation between your Arduino based circuitry and the camera electronics. This means that certain dangerous effects wont pass between these two systems. An electrostatic discharge or a voltage spike from a switching supply can only damage one side, if the isolation was properly implemented.
Field-bound interference e.g. emitted from a malfunctioning BLE module wont be affected and could in turn effect the camera.

As an exampel of an actual product, the cheap Yongnuo RF-603 remotes are capable of triggering a camera. Their electronics appear to use no optocoupler at all. A proper camera trigger is unlikely to damage the camera. A tinkerer could however implement a bad trigger possibly feeding high voltages or curents into the camera. Optocouplers can be misused to minimize the damage inflicted by such a circuit.
This looks different if you want to trigger old flashes remotely. Their high voltages on the trigger pins can actually damage your remote or camera.