Yesterday a user on stackexchange asked me why do I prefer manual over TTL when working with speedlites. I use them mostly off-camera and I've developed a kind of a workflow where I do not walk back and forth between the light and the camera more than a few times.
So my reasons for manual over TTL are:
- cheaper equipment (manual-only speedlites)
- more control (IMHO)
What if any are the advantages of TTL over manual in off-camera use?