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F900 Genlock

Published : 28th June 2004


What do you do about genlocking several F-900's in the field?

I understand that the HDW F900 needs genlock in order to maintain frame accurate timecode. The ideal way to do this would be to keep a BNC from the "Y" output of the master camera to the "genlock in" on the slave. Along with a BNC with timecode. But, say you are shooting with one camera handheld and the other on Steadicam so you need as few cables coming off the cameras as possible (like 1 bnc with HD-SDI). I would genlock and jam sync TOD, then unplug both cables. That should be fine as long as both cameras say on.

Easy enough.

What happens when batteries die? If the battery in the Slave cam dies, and you don't re jam sync or genlock, what happens? I imagine the TC is close, but what happens to the genlock? Are you in danger of "Green Hiccups"? How much TC drift with there be? What if the batteries die on both cameras at the same time?

I read here :  http://jkor.com/peter/trilevel.html   that an external tri-level sync generator is the best bet, but it seems problematic and not very practical. The manual for the F900 doesn't offer much on the topic either.

What do you CML people do in this situation?

Pete Wages
Atlanta



Pete,

Ambient Lockit boxes are designed for syncing HD cameras and providing TC for them without cables. The boxes provide tri-level sync and work quite well.

go here and check it out

http://www.ambient.de/frame_e.html

Randy Miller, DP in LA



> What do you do about genlocking several F-900's in the field?

The Ambient 202CT is the best solution. It outputs time code and sync for the camera (it can be set for a variety of frame rates and output requirements) from an ultra stable internal oscillator. The unit is small (about the size of two packs of cigarettes), robust, and runs all day on two AA batteries.

The unit can be jam synced to another 202CT or an other external TC source so that all sources are then synchronous. You can use one for the sound mixer as well so that everything has like time code. One nice feature is that the units will properly jam sync to unlike code (a 23.98PSF unit will jam to a 29.97I source for example). You would use one such unit on each camera.

Tom Tcimpidis



Pete Wages wrote :

>What do you do about genlocking several F-900's in the field? I >understand that the HDW F900 needs genlock in order to maintain >frame accurate timecode.

We went through this hell on a show that I operated on a year ago.

Genlocking 900's together has other more insidious problems than the Frame/Field issue. IF you genlock two or more 900's together and your genlock cable or connector goes intermittent then you will get a green flash frame and that for some silly reason seems to really upset the production office.

My advice skip it, feed TC through a Clockit box and be done with it.

Eric Fletcher SOC
Steadicam/"A" Camera Operator
Los Angeles, CA USA



Batteries dying on Lockit Boxes will bone you just as fast as batteries dying on the Master Camera or slave cameras.

All are good Options for doing Sit Coms or Concerts or Sporting events. Free running locked timecode on all cameras and sound is Ideal in these situations.

But for dramatic TV Show Feature or Commercial it is absolutely unnecessary.

Use record run on all cameras (they don't have to match)

Let sound do free run

Post people are neither stupid nor so lazy that all the TC on the set must match for them to do their job. Most Post people HATE free running time code.

1) Put Sound on Camera


2) Use Time code Slate (showing Sounds Free running timecode)


3) Clap the Sticks


4) Put Sound Free run timecode on a channel of audio.

Each of these choices alone will work together they make it Idiot Proof.

But You should do whatever works best for you and be considerate and watchful of those that suggest adding additional items to solve problems that don't really exist.

B. Sean Fairburn
HD DP LA
I want you to Succeed, ... efficiently



I try to avoid genlocking F900's on my shows. On one show we ended up removing the genlock anyway due to other issues . It was a 40 min concert, with 4 900's making three passes at the performance, and we had no issues later in post between camera codes and sound code.

On another note, thanks to Jim Iacona for his iRings. They are great!

Greg Foad
DP Toronto



I use the Trilevel Lockit which is made by Ambient Recording. The Lockit is an ultra stable camera mountable generator that makes timecode and tri level sync.

The normal operational mode is to jam sync the Lockit(s) together at the start of the day, attach one to each camera, and let 'em rip. Ambient claims that multiple Lockits will produce timecode with less than 1 frame drift in 24 hours.

I always re jam them after meal breaks

Dave Satin
Video Engineer



Greg Foad

>I try to avoid genlocking F900's on my shows. On one show we ended >up removing the genlock anyway due to other issues .

If you are sending time code to a camera or cameras, removing the genlock may get you in to trouble. Depending on the relative frequencies of the clock in the camera(s) and the clock of whatever your TC source is, they will slowly drift apart from each other at some rate. At a certain point, they will reach a state where the TC and internal camera sync pass through 180 degrees out of phase with each other. At that point, the TC generated in the camera will jump forward or backward one frame to maintain the TC to Sync relationship. This, in of its self is not a giant problem until you get to post.

Then two issues arise :

1) When making NTSC downconversions, you will have a major and prolonged video break-up at the point of TC discontinuity due to the fact that the 3:2 pull down cadence is normally determined from the TC, and when the TC jumps a frame, this cadence has to be re-established.

2) You will have a point of the tape where either a TC frame is missing or is repeated. This is not normally a large problem because the odds of an edit being made of that exact frame are small but it is possible. Also, some hard drive digitizers become unhappy when presented with such TC.

If the cameras can be jam synced periodically, and every time after a battery is changed as they will often jump a frame or two or three at that time, running with no TC and genlock is a fine option. I will often carry one Clockit to take from camera to camera for just such a purpose.

Basically, one needs to determine what works best for a particular shooting and post situation and adopt the simplest approach that will meet those needs. There are almost always multiple solutions to any given problem.

Regards,

Tom Tcimidis



>What do you do about genlocking several F-900's in the field? I >understand that the HDW F900 needs genlock in order to maintain >frame accurate timecode.

With most post routes, you do not need to be super accurate and genlocked unless you are running through a switcher on-set (multicam show), or if you're syncing to monitors. I've found the cameras are often accurate enough without having tri-level sync fed to them. Who cares when the shutter's open on one camera and the other's closed - they're still running 23.976 fps - the sound's in sync. All's well.

If you're doing Select Takes Masters from your Camera Originals and also syncing sound in post, it vastly simplifies things on set, in my humble opinion. And there are tons of good reasons to do "circled takes".

>The Ambient 202CT is the best solution...

Lockit/Clockit boxes seem to do the trick just fine. but I think you can feed time code and not have to feed Tri-Level sync - but I'm not 100% sure about that. I cannot recall exactly all the details of how we solved the lack of genlock when we had the "green frame" issue on a show due to intermittent sync (bad cable).

But as I said, you only need ext sync when you're syncing to monitors or using a switcher or editing with the Camera Original HDCAM's.

Mark Doering-Powell

===================================================

Pete Wages writes :

>What do you do about genlocking several F-900's in the field? I >understand that the HDW F900 needs genlock in order to maintain >frame accurate timecode.

You should use the Ambient Lockit box, since it is both a TOD (time of day) and tri-level genlock generator.

The tri-level genlock ensures the TOD can be recorded in the HD VANC (sort of HiDef VITC...) in perfect sync with images. This TOD can be later extracted to sync the sound on the fly (with a machine like the Aaton InDaw-HD) to produce audio synced rushes on both the original HD tapes and the downconverted SD copies en-route to the editing room.

For European HD-CML'ers :

It can be essential to record the TOD in the VANCs : if you shoot @ 24fps, then downconvert to Pal, you run the original HD tape @ 25 and copy it to HD & SD 25 while keeping the original audio TC in the FilmVANC of the copy.

-JP (of Aaton)



Pete Wages asked :

>What do you do about genlocking several F-900's in the field? I >understand that the HDW F900 needs genlock in order to maintain >frame accurate timecode.

Try Lockit boxes!

http://coffeysound.com/store/ambient.html

Allen S. Facemire
DP/Director
SaltRun Productions,inc.
Atlanta



Both the Dennecke and the Ambient sync box can be powered from the aux 12V out on the F900. Batteries come into play only during power loss of F900. Both seem of equal accuracy. If temperature is fairy even (60-75 degr.) both are good for 20 hours. Denecke is in N. Hollywood Ambient in Muenchen, Germany. Both cost about $ 800.00 today. Of course all 3 wires to camera (sync, TC, power) have to be good and babied.

Dare I ask why Sony did not build this into their cameras 20 years ago? even as a extra price plug in card? [shut up wolf] Wolf ( LA sound mixer and audio book slave writer) Seeberg [new 9th edition in the usual stores with Panavision and HDFW500 sections soon]



What do you do about genlocking several F-900's in the field?

How to record sound on 24P cameras and do the sync ( all this applies to 2 cameras as well as DAT and Camera):

Best cable-less Sound Solution :

Record sound on a second media with TC (DAT, Nagra, DEVA, PD-6 etc). To keep TC on audio identical to TC on video you have to drive the video camera with TC and Tri-level sync. None of the Beta style Cam-corders have continuous TC. There are unpredictable TC jumps when turning power off. These cameras need TC and Genlock (=Tri level sync) from one source or there is serious risk of "green flashes". There are 2 external portable generators on the market that do this in 2003. They do away with all remote sync + TC wires. The 2nd audio track on the camera is saved for audio.

Ambient has a LOCKIT ACL 202T portable battery powered sync + TC generator.

One LOCKIT per camera drives that camera with tri-level sync and TOD TC (23.9). Another LOCKIT can drive the DAT (or whatever audio recorder) with 48K word clock and identical TOD TC at a different but "matching every second" frame rate (29.9). Preferred is to use the DAT as the master clock and jam the Camera LOCKITS (23.9) to the DAT (29.9). This way you do not need a LOCKIT for audio. TC will match every full second. The 202T is not good for cross-syncing. With several Lockits it is good to have the Master Clock ACC 101 which will adjust and match the base speed of each (rental house) LOCKIT. Battery life 15 hours (with a recent mod 23 hrs). It can be externally powered.

Denecke makes the SB-T portable battery powered sync + TC generator. It fulfils the same functions as the LOCKIT. Its base speed can not be adjusted in the field. It does not generate 48K. It is good for cross-syncing. It does all TC rates. It feeds TC and Tri-level. Battery life 3 days. It can be externally powered.

Major Bug in F900 : Intermittens !!!

We have had several trustworthy reports by fall of 2003 of short interrupts in sound from some of the F900 recorded tapes on playback. You can not hear this on the E-E monitor from the camera. This interrupted sound is occasional and random. The cause is not totally clear, but it happens on many TV shows all the time and on some shows only rarely. It happens to one camera out of 4 here and there, never all at one time, some cameras and some channels seem more susceptible than others.

This fault requires a double system audio record setup.

Following seems to be the general consensus on audio interruptus from CML group and others: It is rare but real. It affects both Panavised AND straight Sony F900 cameras. Some rental house never see it others do at times.

Some say :

Power problems can cause it. Genlock problems can cause it.

Some say that audio PLL is more sensitive than the pix lock, and thus marginal problems will show up in the audio before the video. There seems to be no good way to predict it. There seems to be no easy way to trouble shoot for it before listing to downconvert or playback on post decks. You will not hear it at the 5 pin E-E audio out. Once it has happened on a particular camera - setup combination it will happen again.

Be prepared - do double system.

DOUBLE SYSTEM SOUND with two timecodes using no special equipment :

- Feed two balanced audio line levels to 3XLR(F) at rear of Sony F900 camera, or use an RF link to eliminate cables.
- Confirm camera is running at 23.9 Fr.
- Turn EMPH OFF in cameras VTR menu.
- Set LINE-MIC switches at rear of camera to LINE.
- Set "0" VU tone from mixer to -20dbFS on camera level meters.
- Set AUDIO IN switch to REAR.
- Tape down level knobs and switches so they don't move.
- Ignore CUE IN.
- Set camera TC to TOD (Free Run) or REC RUN as editorial prefers.
- Set DAT to 29.97 TC NDF (non drop frame) and 48K.
- Set DAT to TOD (Time Of day) or REC RUN as you prefer.
- Sync slate with audios TOD TC - or transmit REC RUN TC from DAT.
- Clap stix as always letting camera see the slate with readable TC matching DAT.
- For TOD DAT needs min. 10 second pre-roll as always.
- 24P camera needs 10 second pre-roll in TOD for final on-line!
- 24P camera needs no pre-roll with REC RUN as always (You will find it still takes 8 sec to get camera to speed)!
- There is no relationship between Camera TC and Sound TC in this easy setup. Only the slate gives the editors this info.
- Safety + convenience crutch: record DAT TC on an audio track of F900 at - 30dbFs. To eliminate cables use a TC generator [SB2] (sunk to the DATs TOD TC) on camera feeding track 2.
- Protect the whole HD frame visible on HD monitor from boom mike no matter where temporary frame-lines (TV safe or 16x9 etc.) are on the monitor.

- Camera master - Sound follow :

The simplest double system setup would be with a TC DAT set to 29.97 NDF in TOD free run. If you have a hard line TC feed from the master camera you rejam TC at every camera/DAT start, and the DAT TC will match cameras TC. No slating necessary. The DAT TC will then end up matching the 23.97 of 24P camera or 29.97 TC of digital Betacam or Beta SP or DVCAM. If you want no connection between DAT and camera just run the DAT at 29.9 and slate each take with 29.9 as usual in video.

Mixer check list -


* Audio PREEMPHASIS OFF on F900
* AGC OFF
* Camera TC: Record Run or Time of Day TOD?
* Camera: one or many? If many must be TOD.
* TC source: camera? DAT? External generator? Ambient 202T? Denecke SB-T?
* TC connector on F900 is a BNC. Get a BNC to 3XLR for DAT input/output cable.
* Cross Jam DAT to camera direct or with GR-1? Ambient 202T? (painful) or Denecke SB-T (easy)
* Camera Inputs: 2 analog line level, 4 Analog tracks w/ Sony HDCA-901.
* Headphone jack? Not on Panavision as of 2003.
* get Evertz Afterburner HD9150 or HD9155 or HD9155Q - AC only - To get 29.97 TC out in step with 23.97 from camera, it also has video sync out for mixers DAT.
* Audio must be 5 frames delayed for early Afterburner 9150 to match NTSC video output. You need this analog delay for headphones feed matching NTSC and video assist picture. With Afterburner 9155 you need AES/EBU D to A converter, no delay. With HD9155au [9155Q] you get "monitor quality" audio in sync from HDSDI stream.
* Audio return: Get audio line out break out cable: 5 Pin to 2 times 3PinXLR (M)!
* Put all this down on paper in advance and have the powers that be sign off on it!
* DA to drive cameras
* Multiple input monitor mixer to listen to cameras or deck
* Audio delay to match NTSC downconversion on the set

F900 manual at :


/Files/F900_Ops.pdf


A whole book on F900 and Sound ( happens to be written by me)


http://www.locationsound.com/proaudio/ls/SBOK0002.html     and

http://www.trewaudio.com/catalog/items/item96.htm

and Sean has a point!!! as always



>On Behalf Of Wolf :
>Dare I ask why Sony did not build this into their cameras 20 years ago?


Hi Wolf,

It's a good question. Built in to the camera, it would require very little change and extremely minimal additional cost. All that is necessary is to replace the clock oscillator currently in the camera with a higher stability TCO, and add minimal logic to the internal battery circuit already in the camera to insure stable power to the oscillator and TC logic (the current implementation glitches when external power is removed and restored, causing a jump of up to a few frames in TC).

To add icing to the cake, a minimal update to the firmware would provide cross-standard jamming so that it would lock to whatever TC was fed it, like a Clockit. This would allow jam sync from any rate TC source, as the Panasonic Varicam already does. (Currently, the input TC must match the rate and mode to which the F900 is set.)

Why didn't they do this? The best guess is because the F900 is still basically an ENG camera much like the ones that Sony has been making for more than 20 years, and they originally never considered that the camera would be used in this manner...

Regards,

Tom Tcimpidis



>Why didn't they do this? The best guess is because the F900 is still >basically an ENG camera much like the ones that Sony has been >making for more than 20 years, and they originally never considered >that the camera would be used in this manner.

----Clue me in if I am mistaken please :

Aren't Clairmont, Panavision et al offering a hot-rodded F900 with a lot of these goodies "built-in"?

I know that these "custom houses" strip a camera like this down to it's innards and then reman it to their specs.

I just figured that along the way they tried to include a lot of the features that a professional cinematographer would ask for. I haven't had the chance yet to study an F900 *in depth* so again I am all ears.

Jeffery J. Haas
freelance editor, camera operator
Dallas, Texas



>I use the Tri-level Lockit which is made by Ambient Recording. I always >re jam them after meal breaks

I generally don't give my Lockits meal breaks. I figure they should have eaten before they left the house or the rental facility.

Bob Kertesz
BlueScreen LLC



Pete Wages wrote :

>What do you do about genlocking several F-900's in the field?...
>Say you are shooting with one camera handheld and the other on >Steadicam so you need as few cables coming off the cameras as >possible


Pete,

If you want rock-solid, non-drifting Genlock at the cameras and as few cables as possible to each, may I humbly suggest the CopperHead Cine? Over a single, mil-spec, battlefield rated, tactical fibre optic cable, it provides:

From the camera :

HD (1.5 gb/s uncompressed), "Y" channel for menus, stereo audio and time code.

To the camera :

Genlock (tri-level sync), return NTSC video, four channels of audio, and time code. It also provides full camera control with your RMB-150/750 or other RCP, as well as an audio intercom channel.

The cable is actually lighter weight, more flexible, and more robust than any BNC coax. You can drive vehicles, forklifts, even your dolly's over it.

You'll have to provide your own genlock signal at "Video Village," as CopperHead doesn't generate its own.

In Burbank, CopperHeads are available for rent at Wexler, Plus8 and Bexel, as well as some of the other, better rental houses around the U.S. and the world.

Best,

Jim Hurwitz
Manager, Western U.S. & CopperHead Product Manager
Telecast Fibre Systems, Inc.



Jim Hurwitz wrote :

>If you want rock-solid, non-drifting Genlock at the cameras and as few >cables as possible to each, may I humbly suggest the CopperHead >Cine? Over a single, mil-spec, battlefield rated, tactical fibre optic cable, >it provides:

>The cable is actually lighter weight, more flexible, and more robust than >any BNC coax. You can drive vehicles, forklifts, even your dollies over it.

As a Steadicam Operator I'm loathe to have any cable coming off the camera but I have to say that the Copperhead Fibre is THE ONLY solution that I honestly don't mind flying.

This system ROCKS. Plus Jim is a great guy that provides awesome support.

I'm not paid by these guys just a VERY happy user (one of the First actually)

Eric "So do I get a hat or something Jim?" Fletcher SOC
Steadicam/"A" Camera Operator
Los Angeles, CA USA