I use and like the Yongnuo YN-560 III first and foremost with the Yongnuo YN-560-TX wireless controller for manual off-camera flash control. I recently bought a YN-565 EX II not knowing that they run on different systems. For on-camera flash, the YN-565EX II is great for run-and-gun style flash photography, but I more interested in off-camera flash so is there a workaround for these two flashes to work off-camera in manual mode? and what would I have to do?
If you want to trigger the YN-565EX II from the YN-560-TX, you need to add a compatible receiver to the foot of the YN-565EX II. You can use (from oldest to newest):
- RF-602RX (the receiver in an RF-602 Tx/Rx set)
- RF-603 II
The RF-603 II or RF-605 units are the better choices today. The 602 and 603 have very awkward placement of the on/off button so that you can't reach it when a flash is mounted on one as a receiver. The 603 II/605 have the power button as a slide on the side. They also have higher sync voltages, can be used with mirrorless cameras, and have an overall better feature set for not much more money. The 605 adds group control.
However, be aware that this triggering will be manual-only, just as with the YN-560III. You will not have TTL or HSS with the YN-565EX II off-camera.
If you want HSS/TTL on both off-camera flashes, you will have to switch the YN-560III for an HSS/TTL capable flash and use a TTL-capable triggering system.
Today, I would recommend starting out with Godox instead of Yongnuo, because for roughly the same price, you get a lot more function and better expansion options, and particularly because their TTL and manual-only gear uses the same radio triggering system and work together.
You can use an RF-602/RF-603/RF-603 II attached to the foot of the YN-565EX II. You would only be able to fire the flash in manual mode (no TTL, HSS, etc.). You would also need to set the manual flash power and zoom head setting directly on the YN-565EX II flash, rather than via the YN560-TX like you can with your YN-560 III.
If you're shooting in the Canon system, you could also use a YN622C II (or YN622C version 1.2 produced from late December 2014 or after) set in YN560 receive mode to trigger the flash as well as to set manual power and zoom from the YN560-TX. The Nikon version of the YN622 receivers do not have a similar capability.