Video Assist 7" 12G does not work with Canon C300 MK III

I had been using a Video Assist 7" 12G with a Panasonic S1h and it worked fairly well. The other day I decided to try it with my Canon C300 MK III, via HDMI, and received the 'no signal' message. I replaced the HDMI cable with a new ultra high speed cable—2 to be exact—with the same result. While the Black Magic list of compatible cameras does not include the C300 MK III, the BM promo material claims that it will work with any HDMI camera, an apparent contradiction.

I had a similar problem. I had to factory reset the VA for it to work again.

I had tried that, to no avail, I even reset the MK III.

Why would you use the HDMI port when your camera does have a 12G SDI Port?

According to the C300 user manual the camera does not output simultaneously a signal to the MON and HDMI output per default.

Also make sure that you have set the HDMI output of the C300 to scan mode P and not PsF - which is not supported by the video assist for its HDMI inputs.

Thank you for your reply.
I'd used HDMI due to the absence of a suitable BNC cable, but according to Canon Cine support, both SDI and HDMI are generated from the same board, and the camera's scan mode is set to 'P'.
I am beginning to wonder if the problem lies with the camera and the aforementioned board. I have an Atmos Ninja V+ arriving towards the end of this week which, according to tech support, works with the MK III. If if too fails to function properly the camera will be going in for service, as it is still under warranty.

If you can afford a c300mkiii I’m sure you can afford to buy a short bnc cable. See if it works with that then troubleshoot from there.

Whew, that was a low ball, Mike ... LOL.
Of course I can afford a BNC cable, but you cannot buy one at the corner drugstore or supermarket, and I needed the video assist to work until one arrived from B&H. That said, I've managed to find an older BNC cable in the studio and, low and behold, the Video Assist works over SDI. Tech support had indicated that both SDI and HDMI are generated from the same internal board on the C300 MK III, so I am at a loss to explain why the Video Assist will not acquire signal over HDMI???

I’m hindsight, yeah a low ball, was trying to get you into a troubleshooting mindset!

Great, so we know the ‘board’ is working or at least the sdi portion is. Now methodically work your way through the output menus on the c300, quite likely this is where the trouble lies.

SDI is a set standard that tends to work reliably. HDMI is a consumer format that often requires the host and display to ‘hand shake’ it’s a little more finicky. Have you got the c300 working with any other hdmi monitors? A computer monitor at 60fps could be a good test for instance, or try a tv.

Hi Mike,
Thank you for your assistance.
I have tried every alternate setting that the C300 Mk III offers, all to no avail, as it pertains to HDMI. Unfortunately, I do not have any other HDMI monitors available at the moment, although I do have one scheduled to arrive towards the end of this week. In the interim, I will give your computer monitor suggestion a try.

Hi Mike,

I've tried your computer monitor suggestion, and it proves that the camera's HDMI is working fine. That leaves two options
1. The Video Assist has a defective HDMI port, or
2. There is a compatibility issue with the HDMI handshake between the Canon camera and the Video Assist.
The next step involves connecting a different camera to the VA's HDMI port, but my other cameras are out in the field and I will have to wait until one of them returns.
Thanks again.
Ron

I would try different frame rate settings in the camera.

I would try different frame rate settings in the camera.

Hello, and thank you,

Frame rate setting changes had no material effect.

That said, I am 99% convinced that it is a compatibility issue, and here is the logic:
1. The Video Assist works with the C300 Mk III via SDI, but not HDMI.
2. The C300's HDMI output freely transmits signal to a computer monitor, so the output has been proven to be functional.
3. The Video Assist works via HDMI when connected—within the past 30 minutes—to a Panasonic S1h, proving that its HDMI port is working.
4. As per the above, I am left with only one reasonable conclusion, that being that there is a compatibility—handshake—issue with the Canon C300 Mk III/Video Assist 7" 12G combination.
If you, or others, have an alternative explanation, I would be eager to hear it.
Thank you for your assistance.
Ron

Since my last post, I have received a competing monitor/recorder and have found that it works quite well over HDMI with the Canon C300 Mk III. This observation not only solidifies the fact that the camera's HDMI output is working, but also reinforces the HDMI incompatibility theory in re the Video Assist 7" 12G and the C300 Mk III. I will continue to use the Video Assist for studio work, but will avoid the HDMI connection and instead use SDI. The recently received unit mentioned above will be used for all other work.