We did a 3D test shooting and as I tried to figure out if the equipment will work I found out that many people want to do the same and there are many questions about whether and how it works. That’s why I decided to write this short article about how we did it and how it worked:
Setup:
Two Sony F3 with S-Log option on a P&S Freestyle Rig on sticks and Steadycam. 3 Ki Pro Minis for recording, not mounted on the rig. A Panasonic 3D TV as on set monitor.
Genlock:
The cameras were genlocked over an aja Gen10 from Genlock to Genlock port over BNC.
Timecode:
Camera A was set to freerun giving the Timecode over BNC Timecode-Out to Timecode-In of camera B. The KPM-A (KiProMini) took Timecode over HDSDI, as well as the KPM-B.
HDSDI:
There came one HD-SDI cable from each of the two cameras, connected to the HD-SDI (not Dual Link) output of each camera. The F3 was set to 1.5G & S-Log, but the Dual Link ports were not used, as they provide a 444 signal that KPM does not support. That’s why we used the HD-SDI out without any LUTs, to get clean source material. The framerate was 23.98, the 23.98 setting was set to PSF. The KPM setting for RECORDING was set to PSF as well. We flipped the Image for the lower camera on the mirror rig on the camera itself.
Codec:
The KPMs recorded ProRes422 HQ, 10bit.
Gang Recording:
When not moving the KPMs were connected over Lan with a laptop that “ganged” them, thus being able to start both by one click and creating more or less equal clip durations for both cameras. Aja doesn`t guarantee that both files are exactly equal and states that one clip might have a frame or so less than the other. So it was important to have them running with the same timecode and it worked well. When moving there was no gang recording, the KPMs were started manually but still were in sync over the timecode. Actually gang recording doesn’t offer many benefits and you will need a laptop and LAN cables to use it.
Video Assist:
The third KPM was recording a side by side image of a HD Decklink Muxer with a LUT applied. This side by side image was sent over an aja SDI to HDMI converter to the TV. Only this way you can playback in 3D, as the KPMs can’t be synchronized for playback. It recorded in QT Proxy to squeeze file size and thus permitting to get at least all material of one day on one flash card. I didn`t look bad and no one complained. The TV also could be switch between side by side view and 3D.
Video Cable setup:
F3 Hd-sdi OUT to KPM-IN. KPM-OUT to aja distribution amplifier. From there one cable to the stereographers monitor, another one to the Decklink Muxer. This for both cameras and KPMs. From the Decklink one side by side stream to the 3rd KPM and from there to a HD-SDI converter and then via HDMI to the TV.
Sound:
Sound was not in the focus and therefore we only connected one KPM over XLR. As the Decklink Muxer strips audio (maybe aja high5 3D doesn`t) we transported a (noisy and bad) signal from the headphones out to the 3rd KPM (VideoAssist) to have sound on the 3D TV.
Latency/Delay:
Sound on TV was a little bit faster than video due to Decklink processing I guess but still acceptable (the KPM and aja distribution amplifier we used only caused a delay of 1.5 microseconds, measured with an astro). The video delay between TV and live action was about half a second – or from the hd-sdi to hdmi converter or from the TV itself, what I suppose. Alain Derobe (stereographer) noticed a delay between left and right eye on („fast“) movments on the TV but accepted it as a preview device. I don’t know if it was caused by the Decklink or the TV itself. Generally the 3D looked pretty good on that Panasonic Viera Plasma Screen with shutter glasses – much better than Real 3D Hollywood Blockbusters in cinema, maybe also due to the 3D experience of Alain and his daughter Josefine who operated the 3D rig.
Trouble:
One KPM didn’t work for XLR input, it was broken. Another KPM once simply switched off during shooting. The third KPM finally didn’t mount Flashcards when it was cold. I had to restart it up to 12 times until it worked and it always happened if it was switched off for more than 30 minutes. This problem also appeared once on another KPM. Another problem appeared when one of the KPMs simply stopped recording after about three seconds giving the message that video input signal changed what definitely did not happen. I had to reboot it to get it running again. It is very clumsy to use KPM for Video Assist as you have to skip through your clips like crazy, no cues, no overview, not even if computer is connected. But Computer at least helps for file naming, because entering scene 76 if you had before 17 means without computer pressing 59 times that stupid button. The Decklink had to be restarted very very often. Mostly when cameras were switched off and on it produced strange colors, sometimes even when cameras were constantly on. If it was disconnected from USB while operating (it can be configured over software for 3D settings and loaded with LUTs) it often produced an enormous offset between right and left eye stream thus creating a funny 2 1/2D experience. All those problems are solved by simply switching it off and on again within about 6 seconds. When using it on battery while moving it needed more restarts but on battery not moving it was like always, maybe a cable problem. But generally it seems to be a sensitive device. The aja GEN10 genlock gave always close to perfect vertical sync. It lost perfect sync often when only one camera was switched off and on again. Switching Gen10 off and on again solved this problem, except on Steadycam, where the video signal of one camera went through a Decimator (sync measured after that). On sticks one signal also passed through a TV Logic onboard monitor, but that didn’t influence the sync measurement. On Steadycam it took up to three restarts to get perfect sync again, sometimes switching Decimator on and off helped, once we had to restart both cameras to get it done, also switching only one camera on and off helped once. Why? I don’t know.
Resume:
It worked, you can do it, but you will have many devices with many cables for video and Power:
Portable:
(3xKPM, 2xAja DA, 1xDecklink)
All devices were powered over one Bloq battery using the anton bauer plug to an XLR connector that feeded a XLR distributer box. Many thanks to Arri Berlin at this point for making me cables to power the Decklink and aja DAs over battery. As main recording device I never testes out how long the battery will last and changed early enough to avoid trouble. With average recording operation one battery powers that whole setup for about 60 minutes and as they charge fast you won’t need many of them. Not having had the time to get everything assembled well for portable I simply put it in a bag what I wouldn’t recommend for longer shootings as cables suffer a lot. The three KPMs were assembled as one unit over two M5 thread rods and space between them as they get pretty hot.
Stationary:
(3xKPM, 2xAja DA, 1x Decklink, 1xLAN Distributer, 1xLaptop)
I mounted the assembled KPMs with two Magic Arms (one right on left) and 3/8” screws (fits into KPM) to a magliner. The Laptop was also used for Data Wrangling.
So if you are still waiting for your Gemini or don’t have the money for Codex or similar stuff this is a cheap solution to shoot 3D and playback 3D on set. For a long shooting I wouldn`t recommend KPM and its Flash Cards, nor the Decklink. Sorry for my English mistakes, but I think it’s to be understood, if not ask in the comments. And sorry for not showing fotos, I simply forgot about taking some as I really was busy on set being as well Data Wrangler as Video Assist and main recorder.