I do mostly wildlife video and Time Lapse.
When I was only on 70D, my 70-300L gave me all I needed since it behaved as 480x3 mm when necessary, enough for long shots.
Now I changed one body for a 5D IV, the 70-300 performs well but it is a 522mm effectively. Obviously I need more. The Kenko extenders are not that bad, at F16+ the autofocus works and the image is pretty decent in 4k, using the track focus. Sometimes I am shorter even with this rig.
My question is:
What would be a better choice between a Canon 400F5.6+ 2x extender and the Sigma contemporary 150-600 with a 1.4?
Can not have a chance to test any of these lenses so I rather ask fir the expertise of someone you could have tested both.
Please help with pragmatic answers, I am pretty aware of all the specs, rewiews, all the theory about prime and zoom lenses and all the chart checks on reviews. I've been in the field fir 40 years and the reality is that what you get on the final product. The important thing here is that it is video (8.8 MB) and that the 5D uses only a fraction of the cmos sensor, some imperfection intolerable on a photo can go thru in a moving image.
Thanks in advance.