For a good price (vs objectives and converters big names), wide angle we win, very handy when there is little space available. I did not notice any vignetting and no brightness significant difference. The quality seems to be ok. The ring and very short and does not take up space in a camera bag / APN.
With its two lateral coullisses, the ring rises very quickly (clipped in 1sec) over the entire range of threads, and therefore can be mounted on multiple devices.
