I owned the Yongnuo system for a couple of years but never used it on a commercial job. When I tried it on the D850 I had problems and bought the YN622TX. This did not solve my problems.
The YN system has evolved from using identical YN622N units on the camera and remote flashes to a system using a YN622TX on camera and YN622N with the remote flashes. Two or more YN622N work perfectly with cameras of the D7100 era but become erratic with the D810. iTTL and manual are available in both systems with the powers being set on the camera transmitter unit.
Using the YN622TX on the camera removes all the strange behaviour, but the evolution leaves two big flaws.
- The YN622TX has no shoe to mount an on-camera flash. The system does not like any sort of cables so it's not possible to have the TX and an on-camera flash. That is essential for me for weddings as I want one flash on the camera over the lens and another behind the bride.
- The other problem relates to the YN622N which has a foot with pins (for when it's on a camera). This means you cannot mount it onto any sort of metal shoe, and it has no tripod boss. You need a plastic adaptor.
The Godox system sorts all this out and at a similar price (one TX and one RX for $60). The TX has a flash shoe, it does not seem to mind cables between it and the camera or between it and the flash gun. Additionally, it has an on/off switch for a focus laser. You don't need the remote unit turned on to actuate the laser -- ideal for churches. (My SB400 doesn't have a focus help laser.) The RX unit has a shoe fitting (metal) and a threaded boss and no pins -- ideal for a mini tripod mount.
UPDATE
As with all these things the makers don't make it easy.....
- Beware flash guns that are quoted as suitable for Nikon, Canon, Olympus, etc. as these are not iTTL guns. IE, the TT520 is a slave with a 433Mhz trigger. Basically it's manual as is the TT560.
- The TT600 is 2.4 Ghz and can be triggered in iTTL by an X1 TX (N), but it is not usable in the shoe except in manual.
- The TT 685 or V860 II are 2.4GHz and can be used in the shoe or as remotes as they contain the necessary receivers.
- If a gun has a letter after it dedicating it to a particular brand (N,C,S,F,O), then it's usable in the shoe and is iTTL.
- Both systems are easy to set up once you get your brain switched on.
NOTE
If you have no flash guns you should consider the Godox TT series. One gun in the shoe will work fine, but if you buy a second or third, then you can use your original gun as a controller as they have the transmitter and receiver built in. No need for a X1 TX or RX.
