Canon c300 vs Sony A7s 2 vs GH5 for video?

Only the Canon C300 (I hope you mean the EOS Cinema Cam C300 Mark II) is designed to capture video. The Sony and Panny on your list are designed to be still image camera that happen to have a video capture convenience feature.

In my experience, shooting a documentary usually means capturing a LOT of video that gets cut. This typically means video is captured in long sequences in hopes of getting the short duration 20 seconds that might be useful. Under these conditions, waiting for something to happen then pressing record may result in a missed sequence.

Sony A7 manual:

https://docs.sony.com/release//ILCE-7_7R_guide_EN....

Shooting movies starts on page 122.

Page 122 says "continuous shooting is possible for approximately 29 minutes" and that the camera can overheat causing automatic shutdown. Later in the manual, there are alerts about the internal mic recording internal noise and all the normal stuff that a still image capture device will do when using its video capture convenience feature.

The GH5 will be similar to the GH4... and have the same issues as the A7. These issues do not mean these still image devices can't capture good video - but they are not designed primarily to be video capture devices. That means you have workaround to get into your workflow is you want to use them for their convenience feature.

Turn to the Cinema EOS C300 Mark II.

It is designed to capture video. It is not in the manufacturer's "digital camera" segment. Link to the manual:

http://gdlp01.c-wss.com/gds/8/0300019978/05/eosc30...

The first thing you notice looking at the table of contents is that the manual is mostly about capturing video. With the other two cameras on your list, it is mostly about capturing still images - with a small section on video capture.

* External mic connectivity is by XLR connection (page 101) - and the C300 provides for phantom power - common for condenser mics using XLR connections. Pro-grade video and audio. Not a 3.5mm stereo audio input to which you will need to add an XLR adapter.

Audio gain controls are on the outside of the camera - not buried in a menu.

Overheating is not an issue, file size is not an issue and file duration is not an issue. I used to have a Sony NEX-EA50UH which had an APS-C imaging chip, interchangeable lens system, hot-shoe for a camera mounted flash (to capture 20 megapixel stills if I wanted) and XLR audio inputs - clearly a camcorder with good dSLR or mirrorless attributes.

The other not on your short list is the Black Magic Design Pocket Cinema Cam (for a smaller footprint - though only 18080p for now)... I'd say it and the C300 should be your short list and drop the still image capture devices.

I shoot video with a Sony PXW-Z150 (4k or 1080p), HDR-AS2000 (1080p) and HDR-AS30v... after discovering using a still image capture device for video work is using the wrong tool for the job...

You're comparing a very nice video camera that was designed and engineered and manufactured for video recording with a couple of mirrorless cameras designed, engineered, and manufactured for still photos that also have the capacity for short video recording. Have you noticed what has been said thus far? You're comparing a juice orange to a tangerine. AIN'T the same are they?

Of course, the Canon A7s 2 will cost more... but you also get far superior video recording results all day long, twice on Sunday and three times in-between. Make up your mind, do you want to record videos or do you want to take still photos? For whatever it's worth, if you're interested in recording videos, go with the camera MEANT to be used for video recording: Canon A7s 2.

C300 any day of the week and twice on Sunday. The others can't compare.

Follow your nose.

The C300 is an actual high end video production camcorder. It has XLR audio inputs and a form factor better suited to documentary work.

The other two are excellent cameras and even shoot great video but are not as geared to video production as the Canon.

The C100 may be about $3k. The C300 mk II is more like $12,000.

Look at the Blackmagic Mini also. Less money than the Canon. The BLackmagic URSA Mini Pro may only shoot in RAW and ProRes. So keep that in mind. Both large serious files.

Scope it out...

https://www.bhphotovideo.com/c/product/1322801-REG...