Even though the Nissin Di622 is very easy to handle it’s probably just that fact that can put you into a little trap.
After you’ve powered on your Nissin it will automatically start in TTL mode. Nothing wrong with that if you want to shoot in TTL mode.
However, there are situations where you really want to switch to manual mode to get more control over the lighting situation. In my opinion TTL is good but manual is better. But this is another story.
To do so you just have to click once on the mode button. Your Di622 will now be in Full Power manual mode. The next push on that manual button will bring it to half power, then to 1/4 power etc. All the way down to 1/32 power.
Notice that the LED’s of this manual power indicators are burning continuous. This means that you are in manual mode!
The trap here is that if you want to switch from TTL to manual by pushing the mode button longer than 3 seconds your Nissin Di622 will switch into slave mode.
Slave mode is also manual mode you might say and you are totally right. But if your Nissin is on camera and in slave mode it has to be triggered somehow. The hot shoe of your camera will no longer be able to fire it as the flash is waiting for a triggering flash of your build-in flippy-flappy-flash.
This is by the way the only way to remote trigger this flash. It will not work with any radiographic trigger like a Cactus or Pocket Wizard.
Thus if your Nissin Di622 is mounted on your camera and you accidentally activated the slave mode instead of the manual mode you can go insane and probably think that it is broken or at least malfunctioning. Very frustrating indeed.
But here is the good news: when in slave mode, the LED’s of the manual power indicators on the backside of the flash are blinking in stead of burning continuous. This should make ring a bell so you can easily fix it. Go back to TTL and then switch to manual in the proper way.
This is by the way also true if you (vice versa) switch accidentally to manual mode instead of slave mode when you are working with off camera flash.
I hope this helps preventing confusion.