Yongnuo has really hit it out of the park with the 568EX and 622N triggers. Imagine never having to walk over to a speedlite to adjust it again. Control up to 6 groups all from the easy to use LCD screen. Paired with Yongnuo YN-560 III / YN-560 IV, YN660 speedlites you now have the ability to remotely control power output from one easy to use location.
For exposure control, I primarily shoot only at full power and use the flash guideline number and/or a handheld flash meter to determine the correct exposure. the Yongnuo 568EX flash was a great replacement for my OEM sb700s at half the cost, and i cant imagine a better value for the money than these yongnuos if you are looking to get your flash off camera and you arent using Nikons CLS. The Yongnuo 560-TX is a huge advancement in speedlite flash control. Since I tend to use my flash units with umbrellas and soft boxes under studio conditions and since my subjects are not constantly changing their distance from the flash, the automatic exposure control feature is of little value to me. I, however, do not miss this feature because I do not need this feature.
Most dedicated flash units have this feature. Description: YN-560 IV Flash Speedlite is a combination of YN-560 III and YN560-TX, it has built-in trigger system, so you can not only use it as flash. One important feature that the Yongnuo 560 does not have is automatic exposure control. The Yongnuo YN 560 IV is not dedicated to a specific camera brand. small format, medium format, large format, film, digital, Canon, Nikon, Fuji, Pentax, Olympus, and a few others), I prefer not to use flash units that are dedicated to a specific camera brand. Since I shoot with a variety of cameras (e.g. Off camera, and using the YN-560 III/IV built in radio receiver, compatibility will depend on the transmitter unit used. Some of the built-in features the Yongnuo has that I like are the optical slave, radio slave, zooming flash head, variable angle flash head, and the variable power output. The YN-560 III and IV are a single firing pin flashes and are compatible with most cameras having a standard hotshoe when mounted directly on the camera. I was so impressed by the construction, performance, and price of my first YN 560 IV that I immediately ordered two more.