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do i need a sync box to keep an arri alexa TC jammed for a couple of hours?


dominiquegreffard

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All fascinating stuff!

Yes Jan - the camera departments now seem more clucky about digital cameras than in the film days.

The lack of patience to understand the technical requirements of post production are amazing.

The last job I recorded was with a very good DP/Director who would say "I'm running" giving the

loader a heart attack regarding time for slating and rendering the 1st AD as just a bystander!

A couple of years ago working with RED cameras I learned that using a 10 second buffer in my recorder

helped post in the event that camera rolled before sound, otherwise syncing a sound file with less head on it

presented the editor with a time wasting problem.

A recent 2 Alexa shoot I serviced for some reason did not "allow" tail slates?

Anyone know why this should be??

mike

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  • 2 weeks later...
  • 1 year later...

Experienced a 1 sec offset between camera and sound recorder after syncing. lemo-plug straight out my 744 to the alexa's tc input.

I have seen cases with certain cameras where at first glance, there's an offset, but in record, it's fine. If possible, do a test and then take the picture file and sound file, have an editor check it, and see if the timecode matches. Or at worst, check and make sure the TC slate (jammed from sound) matches the camera timecode. A 1-frame offset is pretty typical and not a problem, as long as it's consistent all day.

The Denecke boxes have been very stable and reliable in my experience. It doesn't hurt to send them back to the mothership every so often for a tune-up.

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Mark, thanks for the feedback, I think I'll go with the SB3 for now as it is probably the smallest and lightest option for attaching to a camera.

Reading through all these posts I can't help but wondering if there are situations where a Lockit Box was attached to a camera and used to jam the camera but then sat there passively as the camera was switched back to Int TC Mode.

Not wanting to state the obvious but the whole advantage of an attached Lockit Box would be to continuously feed an Ext TC source to the camera and thus avoid any Int TC breaks or resets.

Presumably the Alexa TC jam procedure would be:

  • Power up the Alexa
  • Go to timecode page by pressing TC button
  • Go into options and change the mode to "Ext Jam" using rotating push dial
  • Connect TC source (SB-3 or similar)
  • Press info button to go to info page, wait for it to say "system good"
  • Press TC button and compare to slate

Can anyone confirm this ?

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Hey Steve

Just shot with the Alexa today and your system for jamming sounds fine, I personally switch the camera back to INT TC after it has taken the jam, then the internal Ambient circuitry will hold the TC for 5 or 6 hours unless power is pulled for long periods, I also check TC after frame rate changes.

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I've now had two recent Alexa shoots where one DP insisted on using external code all day from the SB-T, and the other insisted on just jamming every so often. Both worked fine.

I think the Alexa internal generator is stable enough that it can be trusted. I have seen it momentarily get flummoxed and revert to hour 00, but usually only after a speed change or something drastic. And one swift kick gets it back. Never seen one crash. The only real Alexa problem I've ever had is the operator bumping our scratch track audio feed, or accidentally turning it off. Some camera departments still get very antsy about us hanging boxes off "their" camera.

BTW, I see where Scorsese just announced he will no longer shoot film, and I believe he's sticking with Alexa for his next few productions. These are crazy, transitional times...

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All fascinating stuff!

Yes Jan - the camera departments now seem more clucky about digital cameras than in the film days.

The lack of patience to understand the technical requirements of post production are amazing.

The last job I recorded was with a very good DP/Director who would say "I'm running" giving the

loader a heart attack regarding time for slating and rendering the 1st AD as just a bystander!

A couple of years ago working with RED cameras I learned that using a 10 second buffer in my recorder

helped post in the event that camera rolled before sound, otherwise syncing a sound file with less head on it

presented the editor with a time wasting problem.

A recent 2 Alexa shoot I serviced for some reason did not "allow" tail slates?

Anyone know why this should be??

mike

A while ago mic I did a film where tail slates were banned on pain of death. The reason given was that the post house wanted 100 UK pounds for each tail slate because of the extra time taken to sync the shot up. Not knowing anything about modern syncing up I'm not really in a position to comment but it seems like a bit of a tale to me.

Malcolm Davies. A.m.p.s.

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Thanks Jonathan, Mark and Malcolm, all good input.

The Alexa holds up well in my experience too and on a shoot with minimal location changes and / or different setups, that system seems to be fine. However I think in terms of multiple setups / locations, a camera constantly reading TC from a Lockit Box would just be one less thing to have to babysit as unlike the camera, a Lockit box can stay powered up and produce uninterrupted TC all day long if necessary.

I am assuming though that as long as the camera is in Ext TC / Time of Day Freerun Mode that it will simply read the TC from the Lockit Box without having to go through the jam procedure, effectively acting like a passive TC reader.

I haven't tried that yet so I don't know for sure but will let you know as soon as I do.

Anyone else tried this ???

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I've never experienced any TC issues with the Alexa (attached SB-T's), but I'm curious if part of the problem with intermittent sync issues with jammed-once cameras (no continuous EXT TC attached) might be caused someone in the Cam. Dept. keying a walkie too close to the camera...

The only reason I mention this is because I experienced similar TC oddities with my slates (Denecke TS-2's, TS-C's) several years back due to a shielding issue -- any time the AC's keyed their walkies near a slate, the slate would "reset" back to zeros (the issue has since been fixed by Denecke.)

...anyhow, just a thought...

~tt

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A while ago mic I did a film where tail slates were banned on pain of death. The reason given was that the post house wanted 100 UK pounds for each tail slate because of the extra time taken to sync the shot up.

That's a funny story! I did an entire feature, Billy Friedkin's Bug, where the director's creative choice was to tail-slate every single take in the entire film. And it was all shot on film. I'm guessing this added one hour per day of dailies, so it wasn't a budget-breaking kind of thing ($500 per day, spread out over 3-4 weeks). This was more a problem in real-time HD film dailies, which I believe are on the wane; now, everything is file-based -- even when it's shot on film -- so sound syncing is done by an assistant editor on a timeline. It costs zero now and adds nothing to the session time.

We never had problems with the sound department on tail sticks, but the camera department was frequently guilty of shutting the camera off on the AD's "cut," or just running out of film before they could grab the tail clap. We got very good at reading lips in post.

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  • 1 year later...

" I personally switch the camera back to INT TC after it has taken the jam, then the internal Ambient circuitry "

Sorry for old bump,

Was curious if this is necessary or if the Alexa automatically uses it's ambient clock after you disconnect the source?

Working with a team that doesn't switch back to int tc and say it's never been an issue. So sort of looking to settle the debate!

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You don't need to switch back to internal. At least none of the shows I have done over the last couple years do that, and we've never heard from post.

 

Yes, that will work. I'm told that external sync will now work (it didn't in the earlier Arri software), but have not tried it yet. My understanding is that what the Alexa does with external timecode connected is that it does a "continuous jam," rather than true external. Subtle difference. In continuous jam, it's generating its own sync based on the timecode coming in. 

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I keep an SB-3 on it when working for NFL Films because they jump to 60fps and back to 23.98 between sound speed takes. I prefer it because it is on external and can't get FUBAR'd during the switch.

However the internal clock is very stable, so jamming it in less demanding situations should be fine.

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