After I read a few promising reviews I ordered this little thing.
I’ve done a few tests with it at home and I’m not really surprised about the results. First, it is unexpected good at high focal length (>100mm). But I can’t expect a perfect universal converter for about 110€… with the EF 50mm f/1.4 is it not usable for me (blurry…), the EF 100mm f/2.8 looks much better and with the EF 200mm @ 280mm the image looks good enough for me, so I’ll try it for deeper sky next time!
At least I’ve a converter for my 200mm L-lens 😀
I used a remote shutter controller to avoid shaking and focused carefully in LiveView mode at 10x zoom.
See the test shots (full size: right mouse click, open in new tab/window):