So, why would a flash manufacturer not give this possibility on the display if technically it is available in E-ttl. And that's 2 stops lower as the current 1/128.
however with the current digital displays it would not cost more to add a 1/256 or even 1/512th level. I understand that 1/64 in the past required already several swiths positions or more recent more leds (6) on the backside of the flash. I did look to the link, and I can understand that Ettl is doing a calculation and based on the result, a setup will be chosen which must not be a multiple of 1/3 stop and which might be lower then 1/128.
Thanks to Gammyknee and Privatebydesign I learned that ettl flashes can work at lower power as minimum setup in manual mode.
It is a true "Master" giving three groups in ETTL, HSS, SCS when on camera, etc etc.
My problem/issue with more complicated YN products is compatibility, needing firmware updates for different cameras means at some point your YN flash is going to be worthless, Canon will always give full integration with any EX flash and the 550 is the best bang for the buck power wise (it has the same as a 600EX).
In another thread I even recommended them to another working pro here, Sporgon, he got them and is very happy with his purchase. And a cheap set of RF-602's will get you wireless manual for next to nothing should you ever feel inclined. For a dozen times a year use they are the perfect fully compatible solution for Canon users. If you are going to use on camera only, or via OCC, then I would recommend a used Canon 550EX over the YN any day, indeed I am a working pro who has used 550EX's very happily (sometimes with YN RF-602's) for years and only recently sold my last one after moving to the 600 for different reasons. I have and use Yn products with varying results, though I don't have the 560's. Give it a try, hell, it's only like 70 bucks. And that's exactly what Yongnuo is useful for, someone on a budget that doesn't use flash that much. My thoughts were always "if the 568 EX, for example, does the same job as a Canon 600 RT, but costs a third the amount, then if I could buy a 568 that breaks 3 times and keep re-buying, and get the same amount of wear out of a 600 then I'd probably be doing alright. I just fixed it back into place and it still works fine. At one point, I dropped the 560-II and the front plastic around the IR reciever came off. I use the 568 as a master and the manual 560 as a slave quite a bit, they have decent enough battery life, do the same job as any other flash I've come across, and seem decently built. I started off with a 560-II, and found it very useful, but wanted high-speed sync and auto-options, so I got a 568 EX. I have two Yongnuo flashes, and I think they both work remarkably well for the price. I don't usually speak on this forum, though I only try when I rarely feel I may have something decent to say.