This year I am using the Leica Apo Summicron f2/180mm, with Speedbooster = f1,4/125mm up to f8/720mm with two 2x TC, IQ = amazing, even with 3x crop (GH5) 2100mm in UHD! I wouldn't like to exchange! Canon only shines because of there aggressive advertising.
In 2012 I started filming with the Ti3. If i see the video footage and images now, I always think: What a crap! Never again Canon! The worst price/value proportion on the market.
I meanwhile got my Blackmagic Video Assist 4K, very sharp! as I was hoping for. With a 32.000mah powerbank (0.8 kg) 7 - 8 hrs running time.
I had the Ikan 7" DH7 to enable me precise focus during recording in UHD with the GH4. Image looked like an old Lilliput, not much visible resolution, low contrast, if I crank up brigthness, bright parts where completely blown out, not usable in daylight. I sent it back and ordered the BM Video Assist 4K, hoping for a better image to accurately judge and correct focus in daylight. What is the problem, to finally offer crispy and brilliant OLED 1080p touchscreen monitors like my old ridiculous cheap 7" Nexus has!??? Is this against the law????
EF mount is too much limiting, no speedboster, 1.6x crop. If they would make an alternative MFT mount, then it gets interesting. A numb MFT mount would be enough for me, I anyway do everything manually. Technically it would be very easy and cheap, but BM obviously doesn't understand. So, I probably will continue next year with Panasonic GH6 or something like Sharp 8K MKII