andrgl

It's well documented that zooming while shooting with the 12-35mm X lens changes aperture and focus.  Also the lens is not parafocal at all.  If you want a parafocal lens, then the Sigma 18-35mm F1.8 is the one to get.  And I have the Canon 24-105 F4L and it isn't parafocal either.
 
BTW that Lumix 14-45 kit lens is crap.  I had it and sold it.  I highly recommend the Sigma, or one of the Panasonic PZ lenses (Power Zoom) if you want to zoom in and out while recording video.

The lighting and grade were killer.

But man does the BMPCC just LOVE to kick out that shitty magenta grid pattern when exposed to flares. :/

Génial! It's so obvious but I had no idea light could roll off that gradually.

Merci beaucoup.

in the full body shots the background is so even because it has been extended in post see form this raw grab:
 

 
All other shots the backgrounds are real, a big soft light from above lit it evenly.
 
If you want an even lit background you can start by placing your light as further away from it as possible.
The closer you get the more you will see the gradation in the light fall off and you will create a visible gradient.
 
Found this image that demonstrates it clearly:
 

 
as you can see the light intensity changes rapidly between the 22 and 5.6 mark, so you will see a gradient.
If you place it further away, starting at the 5.6 mark and around the 4 mark you will have less of a gradient (although you will have a 1 stop difference as demonstrated in the pic)

If you couldn't follow the story you might want to try something simpler. Thor 2 might be more ya speed! Great film, the consistency on Thor's hammer throughout the film is flawless and leaves you feeling satisfied at the end of the film. I thought about his hammer for days afterwards....

To me 5d3's raw format beats all gh4's prized features (4k, price, 96fps, lightweightness)
The look which you can pull out of the raw footage is priceless, imho.
But when you doesn't need raw then of course gh4 is a winner