70-300mm VR + Kenko Pro 300 1.4: Severe Back focus at 300mm
Just yesterday discovered that my 70-300mm VR with Kenko 1.4X Pro 300 backfocuses a lot at 300mm. I immediately applied AF tune up to limit -20. By the way, a very nice feature discovered: Lens+ TC shows up in a list of saved lenses as a new lens 70-300X1.4.
Well, -20 improved focus a lot, close but no cigar. Need something about -25 or -30.
Interesting that at 200mm back focus is not so big and I can compensate it but 300 mm is a real nuisance.
Can anyone advise a service that can adjust Kenko 1.4X?
Edit: Forgot to add that manual focusing works perfectly... if I'm getting lucky to focus accuratley at this length.
Also: 70-300mm VR without TC autofocuses pretty well, no need for tuning.