This lens is often mentioned as good for wildlife filmmaking, but is it really good for serious work in super35 and full frame environment? In photography, I would never even thought about it, having prime 600mm, but possibility of zooming is also very important in the film. Is there any firsthand experience with this lens, in terms of image quality, also ergonomics and tripods? Any alternatives?

I have a Sigma 800, Nikon mount, which I used with my Lumix GH4s. Very heavy and awkward even on a heavy tripod.
I now use a Sigma 150-600 plus 1.4X TC, Canon mount, on my GH4s via a Metabones Smart adapter.
Much more manageable, zoom which very important, and image quality okay.
Obviously I have a bit more depth of field (as well as a 2.3X crop in 4K video), than would be the case with a Super 35 sensor.
Ron

I'm using the 150-600 as well, basically the exact same setup as Ronald described. I love it and think it's an amazing value. But as mentioned, I'm not using it full frame.

The 300-800 can be a good tool to use in the field.

You first need to try your hand at smaller zoom for DSLRs, i use the 100-400 of canon most of the times on my Panasonic GH4.
on a super 35 the 300-800 may be nice to use, however you need to have other things in place to hold the complete assembly in place, as the 300-800 will make things huge to handle is what you need to consider in the field.
Do give a smaller zoom a try and then consider going to a bigger one if you are comfortable with the setup.

Thanks. I already have Canon 100-400 IS II with TC1,4, but I need longer reach. Not to shoot from 1 mile (I am usually less then 50 m from the animals) but for these beautiful face close-ups.

I might the Sigma 150-600 first though.

Hope its not too late to chip in, I use the 300-800 on quite a regular basis and the only gripe is the weight. I use it on the FS7 with Reallyrightstuff long lens support balancing both the camera and the lens. Everything is supported on a Vinten Vision 6 and Gitzo CF legs.

Sharpness is excellent and I love the zoom range but given that the 150-600 zooms are pretty competent now, I will take a look at those first.

Hi Goran,

I have used the Sigma 300-800 a great deal for high end natural history filming (F55, Red Epic etc). Its an extremely good but very heavy and slightly unwieldy lens that needs a solid tripod and 19mm support (or a flat plate support. There is nothing else in its class aside from HD B4 mount lens with an IBC HD to S35 convertor. In the right conditions one can even use a teleconverter.
Its not a lens you can easily move around with though, best for work in a hide...
I hope its OK to post this here but mine is for sale, in near mint condition. Its a Nikon version so you get the manual aperture ring. Send me a PM for information.
Warm regards,

James