LED hardly light up with 4n35 optocoupler

[system]

Never mind
The problem was in the code, I forgot to put pinMode() in the code

So now my code is:

const int cameraShootPin=11;

void setup(){
  pinMode(cameraShootPin, OUTPUT);
}
void loop(){
digitalWrite(cameraShootPin,HIGH);
delay(2000);
digitalWrite(cameraShootPin,LOW);
delay(1000);
}

Stupid mistake, hope it helps someone else in the future