Blackmagic Forum

Hi,
I'm trying to get the focus value of a BMD studio camera 4k through the atem API.
In C# with BMDSwitcherAPI, I'm using:
...
IBMDSwitcher m_switcher;
...
cameraControl = (IBMDSwitcherCameraControl)m_switcher;
...
double focus;
cameraControl.GetFloats(cameraID, 0, 0, 1, out focus);


The range value from the whitepaper is [0-1] in 16 bits.
But If I do an autofocus with the atem software interface and after I do a get in C#, I receive "-13,6745...." If I turn the lens ring to minimum, I get the same value, to maximim, the same value.

But if I set a value like "0,83" with cameraControl.SetFloats(cameraID, 0, 0, 1, 0.83), my focus is good.

In other words, I want to read the focus value after turning the physical ring of the lens through the atem API.

Hi Benoit,

The camera control interface is unidirectional from ATEM to Studio Camera via SDI. As such, the focus value read back via IBMDSwitcherCameraControl is what has been locally stored on the ATEM.

Regards
Cameron

Is this the case for all cameras? It would appear to be so. I can programmatically set the focus on my Pocket 4K via my ATEM Mini, and I can trigger an autofocus. But if I then use getFloats, I get the last value I sent manually, not the result of the autofocus. Is it not possible to read this information?

Still the case!! Atem is ALWAYS master and so there is no data readback available when using the Atem setup.

On bluetooth it might be different.. But the SDI and HDMI control protocols do NOT support any feedback...