Is there a good cheap optical slave flash on the market?
There are quite a few models on Ebay, some with manual power control and built in slave, for about $35. Pawn shops and camera stores with used gear are also good places to look. I prefer radio to optical slaves, I’ve had to many issues with optical. So far, my radio slaves have worked every time, no matter where I am in relation to the flashes. They are much more reliable outdoors, and have much better range. That, and somebody else with a camera won’t set off your lights! I bought the latest greatest Chinese set, transmitter and 3 receivers, for $45. They work with my Minolta hot shoe flash, old Vivitar hotshoe, 2 Sunpak handle mounts, and 2 Metz handle mounts. I can put a hot shoe shoe flash in the socket, and connect a handle mount to the PC sync terminal, and fire both flashes at once. One of my optical slaves may be able to do that, I never tried!