Yongnuo CTR-301. Very recently this product came under our radar. There were good and not so good comments about it. As we have photographer clients and before they asked questions, we thought we better try it out. It works for Nikon, Canon and Pentax, and we don't think we'll buy other cameras for the purpose of running tests (unless you provided them and depend on us for analysis of non-destructive test reports) . Switch the receiver to 'W' mode; you're radio-synched at channel 4 with your flash. Get the transmitter out of the way and switch the receiver to 'L' mode, your flash is now an optical slave like any other studio ones hanging around.