The flash unit is really mini, really weighs only 75 grams with 2 AAA batteries (which are not included). It has a green illuminated pushbutton with which you turn on and off the device, a glowing orange flash lamp and a lever for locking, all there is. There is no separate autofocus assist lamp, which was otherwise resolved by the flash fires stroboscopic bursts, so long until the autofocus of the camera focused. All settings are made via the Canon camera, for example: Flash firing Disable / Enable: When Suppresses the flash will not fire, but the work already described AF illuminator function. There is also a wireless function, is based on optical transmission. In this case, the flash works as master and solves the / the slave (s). As a master, he gives off no flash. Mounted the 90EX is in my case on a 5D Mark III. In wireless mode can be activated (in optical mode) a 580EX II and 600EX-RT a, either both parallel or in different groups. The guide number is given as 9, which is slightly less than, for example, the built-in flash of a 60D, it has a guide number of 13 indoor shots are feasible, of course you can use the flash exposure to brighten. Flashed objects are beautifully illuminated. The light angle is specified with 24mm
Conclusion: The Speedlite 90EX is working as hoped and will now always be there.
