Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: Currently I have two Yongnuo YN622 Flash units. Will this YN568ex work without the need for an additional receiver?
Document: I've owned this for about 2 weeks, and so I've been very impressed. It seems to work seamlessly with my Canon T3i, and does everything I need it to do and more. I still haven't explored all the features, but the HHS works great! It's nice being able to go all the way up to the fastest shutter of my camera, and still use a flash.
The unit work just as advertised even more power than I thought it would have.I see no reason to order the Canon units when you can get this with the YN 622c's for less.
This is just missing a &#34;Master Flash&#34; setting out of a myriad of awesome features for the price I paid: $182. But even Yongnuo went further in their next model by making the YN 568EX II a Master. I've had this flash for several months now and absolutely love it! I own two of these now with a pair of YN 622C transceivers.
I own several Yongnuo units and they are all great. This ones matches Canon's offerings in almost every department. Save yourself tons of money and get one of these!
it worked once. However, while I was covering a wedding, the flash unit jumped to ETTL and got stuck there. Pressing the Mode button would not work. So now I can only shoot in ETTL. Emailed Yongnuo, they told me to contact the re-seller. Did not even offer to give me a solution on how to fix the issue. Went on a few forums and found that some other users of the YN568EX also had that problem. None of them found the solution.
I ordered two of these and have not had them for very long yet, but I did hold off on the review long enough to make sure that they didn't die within the first few weeks. So far so good! I have tested these on a Canon 5D Mark II.The build quality is absolutely good enough for professional work, especially since they are less than half of what the Canon version costs.
I've become a Yongnuo evangelist... there's absolutely no reason to spend over twice as much on the Canon equivalent when these work just as well. I'm not so nervous about having these swaying around on a 9-ft light stand precariously perched on a boulder.
I can't wait to buy more of these!!! Flash worked perfect for my shoot!. Shot about 1,000 photos without a problem. I was using it as an on camera flash!. Everyone should own one.
You can play around with the strength of the flash (ex: -2/3) depending on how strong you need the flash to be. The pictures turned out great! It was so nice to finally have no noise with my indoor photos. I even used the flash during the outdoor ceremony because they stood in a gazebo, which made them very dark while the outside lighting was light. I was able to shoot at the back of the audience and have their faces well-lit.
I have only used my 568 for a few sessions. I use it as one of my off camera flashes. So far, everything confirms this was a good choice. The results are as expected and the flash just feels solid. HSS and the sound when recharged are two reasons I really like using this one.
Answer: If you want to use the YN568ex as a master flash it won't work as it works only as a slave flash I would suggest getting the YN568ex II same model but updated and can be used as master flash to set off other flashes.