EPIC genlock and shutter phase

[Dave Winder]

Hi Jason

Can you let me know the sw version number precisley? I am surprised you have so many non syncs in the EPIC Sync column. Had you performed a user black shade calibration and are using it?
Lastly, in your rig, does one camera record an upside down image?

thanks

[Pedro Guimaraes]

Hi Jason

I am surprised you have so many non syncs in the EPIC Sync column.

thanks

...umm.......I'm not.

[Dave Winder]

Pedro, if you are seeing problems, I would love to hear details.

Jason, its great that you put this together and go through this. I went through all the ones you have marked as Epic Sync = no, with version 3.0.0, but with a dark shading correction performed and enabled. This allows the higher frame rate cases to work.
In fact all of those do work and show green SYNC icon, with the exceptions of the ones in the 25fps project settings. The 120 and 96 fps cases are not valid conditions since they are not multiples of 25. Changing the 120's to 100's and eliminating the 96fps/5K (you cant get to 100) case clears all those up.

As for the slight phase difference, I believe its because one camera is probably upside down, or essentially seeing the world upside down, so the rolling shutters are not scanning the world in the same direction. I dont know for sure if thats true on your rig. I think if you play with the placement of the slate vertically in the scene, you can make the amount of phase difference increase or decrease.

[Jason Goodman]

Hi Dave,

Sorry I was off the list for a few days. This was all done with version 2.08. We did not do a black shade beforehand. That is good to know if that makes a difference. I will upgrade to 3.0 and can do more testing tomorrow or Thursday. The BX3.5 mirror rig orients the cameras such that both sensors image top down. The image gets flipped horizontally in CineX to minimize rolling shutter 3D artifacts.

[Jason Goodman]

Dave,

After your previous message, we upgraded the EPICs to 3.0 then proceeded to black shade both cameras. What we found was that in the Time Base of 25, we got proper sync indications on the camera and also in our visual check of the recorded material for 4K 100fps, 4K 75fps, and 4K HD 75fps. These modes did not work properly in our previous tests of 2.08 without black shading. Our document has been updated and the new doc is here:

https://docs.google.com/spreadsheet/...lE&output=html

It is possible that 3.0 and blackshading may have enabled additional working 3D modes, but the cameras had to go out on a rental. We will conduct more tests when they return.

[Rich Schaefer]

Very good to know that the black shading could effect varispeed syncs!

[Dave Winder]

Hi Jason,

thanks for the update. Thats not a convenient side effect. User black shade calibration is required to get those higher framerates to sync.

[Rich Schaefer]

User black shade calibration is required to get those higher framerates to sync.

HI Dave, why is that? What is going on inside that black shade, a noise/color thing in my mind, is related to high speed shutters syncing?

[Tom Funk]

To add my story to the mix - my two Epics were just out on a shoot where they were shooting one of the days in 3D. First, when trying to black balance the one camera, it failed to the point where I have to now take it back to RED for repair. But with the replacement camera that they had to rent last minute, they shot their 3D. Turns out that despite the apparent genlock when shooting, the footage is in fact out of phase.

I had originally tested the sync of my own two cameras - using a digital stopwatch and watching the frame blending, etc - and had no problems, though I frankly didn't do a comprehensive test of all resolutions and frame rates... I think we just tested 24 and 72. Regardless, I did not re-test that once I'd upgraded to v3 firmware.

Now it looks like two full shows might have been compromised. (Not to mention the extra cost of renting another camera last minute, though that wasn't a 3D issue.)

[Jason Goodman]

Hiring a camera is one thing. Hiring an experienced crew is another. Digital cinematography is complicated. 3D adds additional complexity. Save your clients from themselves and make sure your gear goes out with crew that know how to operate it.