Work pefectly with my Metz 44 AF-1 flash.

This product saved me buying a new flash. I use an old Nikon sb24 as a second flash with this optical slave for portrait work indoors and out

Funktioniert anstandslos , nichts dran auszusetzen.

I used it with Canon M200 and Metz 54-MZ4i flash. Set camera to manual exposure ISO100 and f8 1/125 and Metz to “A” and matching ISO and aperture. The Metz flash will take the light from internal flash in exposure control too and the fact that M200 internal flash at low ISO is under powered helps. If needed, block or tilt the internal flash upwards to minimize light contribution from it.The only cons is the slave trigger unit cannot be properly and tightly secured on cold shoe rig. 1 star off.

The JJC Optical Flash Slave Trigger (JSYK-3B) is well-built and works great with my old Minolta Auto Electroflash 360PX from my film days. I avoided using that flash after switching to Nikon digital SLRs because I didn't want to risk a direct connection and possible excessive voltage. However, I learned that you can still use older flashes in manual mode with the JSYK-3B -- there is no direct wiring to the camera -- as a secondary flash where you have a main flash (or multiple flashes) controlled by the camera. The light from the main flash(es) is seen by the JSYK-3B and it fires the flash attached to it; this happens simultaneously because the light reaches the sensor effectively as fast as if the unit had been wired electronically.Bear in mind that this is old tech (optical slave trigger technology has been around for a very long time), but it still works well. The key thing to remember is that many modern digital cameras have sophisticated flash systems that emit "pre-flashes" first that can trigger an optical slave right away, before the "real" flash and shutter exposure happen. You need to set your camera so that it does not emit extra flashes so the slave is not triggered prematurely. Usually there is a flash setting for "manual" (you control the intensity of the main flash manually) or "auto" (the main flash uses its own sensor to control the strength of its light burst), either of which will eliminate pre-flashes. Also, don't use the camera's "red-eye" control either, because it is usually based on emitting pre-flashes.The JSYK-3B sensor is sensitive and is inside a curved lens that allows it to "see" flashes that are even a bit outside a direct line of sight. I have not tested how well it works in direct sunlight (which might drown out a weaker primary flash), but indoors it is sensitive enough to be triggered by my Nikon's built-in pop-up flash set at its weakest (1/128th) power. The package claimed it could be triggered by a main flash 66ft away depending on the power of the main flash. At 1/128th, my pop-up triggered at 15ft.This device is a better deal than others I found while shopping because it actually gives you three functions in one: (1) optical slave flash trigger as described above; (2) the bottom has a metal 1/4" female mount plus cold shoe, and the top has a hot shoe, so it gives you a way to attach any flash to any tripod or light stand that has either a standard 1/4" male screw attachment or a cold shoe mount; and (3) there is a standard female PC terminal on one side that is triggered whenever the optical sensor triggers the hot shoe, which means that the JSYK-3B can trigger a second flash via the PC terminal simultaneously with the flash mounted atop the hot shoe (or even just one flash attached by PC cord alone). The PC terminal on mine worked flawlessly; I simultaneously fired a Minolta 360PX in the hot shoe and a Nikon SB-800 connected via PC cord, using my camera's built-in flash as the trigger. (See photo.)In short, if you are comfortable with using flashes in manual mode and not relying completely on your camera's TTL flash control, this little device gives you a very inexpensive route to exploring wireless multiple-flash setups, and lets you revive older flashes that you might have stored away.