Review on 📸 Canon EF 2.0X III Telephoto Extender - Enhancing Canon Super Telephoto Lens Capability by Kevin Ilango

Every professional reviewer is quick to point out that this prevents AF with slow lenses, but today I found that with this addition, both the Canon 5D4 and the Canon 7D2 perfectly auto-focus Canon 100-400 L f/5.6 lens in Live View. On the 5D4, this registers as a minimum aperture of f/11; On the 7D2 he shoots at f/9. I have no idea why that is. However, both cameras were able to autofocus the lens in Live View without too much trouble. Yes, autofocus is slow compared to normal use, but that's by design (and well beyond my understanding or the scope of this review). My quick test consisted of random shots in my garden in bright sunlight; I also put on a 10 stop ND filter and photographed in full sun. Autofocusing on the sun is a little tricky, but if you put the focus square on the diameter, it gets the edge and then it locks in instantly. The only other test I did was with the Canon 135L f/2 lens; The 5D4 auto-focuses through the viewfinder, resulting in a 270mm f/4 lens. I'm not sure if that's a good thing, but now you know. I haven't tried it with 7D2 yet.