Had a colleague bring in a couple of Ninjas. When we went to shoot 23.97 on our Sony EX3s, both had trouble locking in the signal. We did use some AJA HA5s to convert from HDSDI to HDMI however.
That said once we went to 29.97, they didn't have an issue.

Were you providing motion for the Ninjas to detect cadence with?

Hi Gary,

I am not sure what you mean. Yes, we were sending 23.97 video signal to the Ninja.
I have never heard of any device needing video signal that has motion - like an object moving around in the frame before it could sync, but since every camera's signal does change slightly = noise floor fluctuation, I guess my answer would be yes.

Again, 29.97 was the same signal and that got the Ninjas to both sync.

23.976P is normally embedded in a 29.97P stream with pulldown - thats what he meant by cadence. I'm reasonably certain that is the way the EX3 does it. Maybe the pulldown flags were lost in the sdi - hdmi conversion? Shouldn't be tho.
Can you set the Ninja to look for pulldown? I know I can on my Nano..

The Ninjas were a owned by a colleague. I'll have to check about this next go around.

So, you have not had any issues with 24psf?

TIA!