I just finished my second serious portrait shoot using Yongnuo flashes and radio controllers. Overall, they are a good value for their price, although with the low price comes some trade offs. My Yongnuo flash equipment includes: one YN565EX speedlite, two YN568EXII speedlites, three YN622C radio transceivers (attached to each respective speedlite), and a YN622C-TX radio controller (attached to the hotshoe on the 7D). On the portrait shoots, I worked using a wireless tether to my Canon 7D via a TP-Link TL-MR3040 portable router and the qDSLRdashboard app running off of a Nexus 7 tablet. (More on the tethering part in another post.) I won't go through a detailed description of the Yongnuo equipment functions, as there are many sites on the internet that contain highly detailed accounts. Here are some observations of function and performance in real-world conditions operating in manual flash mode:
1. The radio controllers are a piece-of-cake to operate, especially the YN622C-Tx with its LCD screen. They seamlessly function with the 7D's flash menu. Nothing more to say.
2. I opted to have one YN568EXII on channel A as the key light, the second YN568EXII on channel B (fill light), and the YN565EX on channel C (back light). The YN622Cs communicated effectively with the newer YN568EXII speedlites, but not so well with the older YN565EX flash. This was particularly evident when adjusting the zoom using the flash controller: YN568EXII response was instantaneous, with the flash zoom adjusting according to the controller. However, a request to change the zoom on the YN565 often required two or more clicks of the controller. Similarly, using the controller to adjust the power of the YN565 often resulted in the flash missing a change, staying at the previous power setting, and then jumping two adjustments. Cleaning the contacts, resetting the YN565 to factory default, using different transceivers with the flash, or changing the channel used by the transceiver did not correct this YN565-specific problem, which happen about 5-10% of the time. Lesson learned: I use the YN568EXIIs for mission-critical lighting, the YN565EX is more for backup or used when I'm not "on the clock".
3. Similarly, while the YN568EXIIs fired each time they were remotely triggered, the YN565EX occasionally did not fire. This misfiring occurred at about 5-10% of the time.
4. The speedlites function well with rechargeable NiMH batteries (1400 mAh), but a steady hour of photography creates quite a lot of heat through battery discharge. From my limited experience, a set of four NiMH batteries last ca. 90 minutes under these conditions. Next time I'll use alkaline batteries for a comparison.
All in all, my initial experience with this Yongnuo equipment has been favorable, with the caveats mentioned earlier. I plan to update this post in time once I have more time using this equipment.