Freeheel

Quick question about tentacle sync

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Freeheel   

Hi All,

I've got a question about the Tentacle sync units.  I'm going to be using some next week.   When they are synced, do they flash in time with the  timecode on the second, like the Ambient and Mozegear units do?

The reason for my question is that when using the Tentacles for TC on a camera audio track, you can't just look at the camera to see whether time code is matching the audio recorder.

With the Ambient, Mozegear and Denecke lockits that don't have timecode displays, the flashing "on" light matches the top of every second (or 2 seconds) so you have at least some visual clue of whether the unit is still in sync.

Do the Tentacles have this feature?

Cheers,

Brent Calkin

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Lucas   

There is the tentacle setup app for the phone this allows you to see the current TC and adjust framerates etc.

 

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Apcki   

There is no display, but a little led light does blink on the top of every sec.

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I'm not sure anyone would have the super human ability to detect accurate sync down to a 30th of second by watching a blinking light........... it is however useful to show the status of the unit and also the battery condition.

 

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Klaus   

Between 1992 and 2012 this was the only - and still sufficient indicator on our Lockit boxes - and honestly, it works surprisingly well (and way better than any kind of LCD/OLED) as it actually is not blinking but rather flashing.

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On 9 Apr 2017 at 4:40 AM, Steve Foy said:

I'm not sure anyone would have the super human ability to detect accurate sync down to a 30th of second by watching a blinking light...........

in comparison to the easy task of detecting accurate sync down to a 30th of a second by watching flickering numbers on two different screens? : )

jokes aside, I actually think it's easier to see a  two frame difference by holding the flashing LED next to each other then through two timecode displays. on the other hand it's harder to see if something went several seconds (or hours) astray. 

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12 hours ago, Klaus said:

Between 1992 and 2012 this was the only - and still sufficient indicator on our Lockit boxes - and honestly, it works surprisingly well (and way better than any kind of LCD/OLED) as it actually is not blinking but rather flashing.

9 hours ago, chrismedr said:

in comparison to the easy task of detecting accurate sync down to a 30th of a second by watching flickering numbers on two different screens? : )

jokes aside, I actually think it's easier to see a  two frame difference by holding the flashing LED next to each other then through two timecode displays. on the other hand it's harder to see if something went several seconds (or hours) astray. 

Blinking/Flashing, whatever, it's irrelevant. My point is that no human can ascertain the accuracy of a millisecond timebase system simply by observing a Blinking/Flashing light or an LCD/OLED Display. I'm sorry but it is just not physically possible. Think about it, if it were possible, we would have to shoot at much higher frame rates than 25 or 30 fps to fool our brain into perceiving smooth motion.

Just to be clear, the Blinking/Flashing light on the Tentacle (or any other Lockit Box) should only be used as a confidence check for the 'Status' of the box and/or the 'Condition' of the battery.............. that is what it was designed for !!!

 

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Blinking/Flashing, whatever, it's irrelevant. My point is that no human can ascertain the accuracy of a millisecond timebase system simply by observing a Blinking/Flashing light or an LCD/OLED Display.

That's not true. The human eye has a resolution of about 60 frames per second. Film shot at 24/25 fps works because of an optical illusion. So it is possible for us to see a difference of a frame between two blinking LED

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38 minutes ago, Constantin said:


That's not true. The human eye has a resolution of about 60 frames per second. Film shot at 24/25 fps works because of an optical illusion. So it is possible for us to see a difference of a frame between two blinking LED

You're probably correct.......... but what if it was a full second out ? How would you know ?

At best the blinking/flashing light on the Tentacle may offer some sort of clue as to the relative sync of 2 or more units, but I certainly wouldn't rely on it for anything more than it was designed for which is to indicate the 'Status' of the box and/or the 'Condition' of the battery. That is why it is only ever referred to in the documentation as the 'STATUS LED'.

 

 

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You're probably correct.......... but what if it was a full second out ? How would you know ?
At best the blinking/flashing light on the Tentacle may offer some sort of clue as to the relative sync of 2 or more units, but I certainly wouldn't rely on it for anything more than it was designed for

Of course, it's only a quick confirmation. But I don't see how two Tentacles could run exactly 1 second apart, that seems rather unlikely. Still think it's more useful than a display. I sometimes do a loud read-out with the camera dept and a second offset would be obvious then. That in addition to the blinking led is pretty useful. Or I can hook up the Tentacle to my phone

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39 minutes ago, Constantin said:


Of course, it's only a quick confirmation. But I don't see how two Tentacles could run exactly 1 second apart, that seems rather unlikely. Still think it's more useful than a display. I sometimes do a loud read-out with the camera dept and a second offset would be obvious then. That in addition to the blinking led is pretty useful. Or I can hook up the Tentacle to my phone

Useful yes, I totally agree...... but definitive, no.

 

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Hello, I think Steve has a good point there about humans not being able to see that. But I think the bigger problem, in this scenario, is one would also need to know how long that led was staying "on". And what is the definition of "on"? The led has to ramp up to full brightness, and then has to diminish down. So, what part of that illumination is considered "on"? If you look at a Denecke slate, When it is clapped, if you have it programmed to flash for 2 frames, that's a 12th of a second. Does anyone here read that display? Or even see the flash? 

Sincerely, Martin 

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Hello, I think Steve has a good point there about humans not being able to see that. But I think the bigger problem, in this scenario, is one would also need to know how long that led was staying "on". And what is the definition of "on"?

I think you may be missing the point. The original enquiry was about comparing two Tentacles, to see if they are in sync wirh each other. These will most likely have the same on/off behaviour.

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Hello,I think that furthers my point. If you can't look at one led and calculate when it is "on", due to the ramp up and bleed down of the leds, how can you come to a conclusion on 2 leds located on 2 different units. In that scenario, your eyes would have to be able to see both leds at the same time, and calculate when both leds are at full illumination, since that would indicate when these 2 were "in sync". That's ever harder than analyzing one led. A dog that can't catch one car can't catch 2 cars.

Sincerely, Martin 

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Hello,I think that furthers my point. If you can't look at one led and calculate when it is "on", due to the ramp up and bleed down of the leds, how can you come to a conclusion on 2 leds located on 2 different units. In that scenario, your eyes would have to be able to see both leds at the same time, and calculate when both leds are at full illumination, since that would indicate when these 2 were "in sync". That's ever harder than analyzing one led. A dog that can't catch one car can't catch 2 cars.

Sincerely, Martin 

But the dog can look at two cars.

What's the point of looking at just one LED? You just need to look at two Tentacles (in this case) and their respective LEDs. If you hold both in one hand the LEDs are about 2cm apart - at most. Both LEDs will have the same "ramp", both LEDs will blink at the same time, just like they do on the older Lockits and so many other devices. It's one of the easier exercises. There is no need for calculations of any kind

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I've been following this discussion with some degree of confusion. I expect this is a matter of my lack of familiarity with the specifics of Tentacle gear and hope that one of you might clarify the matter for me.

I'm generally familiar with the Denecke sync boxes. The operation light on those units will blink furiously when the device is first turned on and then settle down after about a minute of run time. However, if the device is jammed, the light immediately goes from rapid-fire to one blink every second. Seeing the stable flash confirms that the jam has taken and that the two clocks (source and slave) are either set to the same frame rate or to compatible cross-jam rates. 

The difference between rapid-fire blinking and once-per-second is conspicuous and no special 60-frames-per-second vision is needed to differentiate the two.

Do the Tentacle units operate differently? Does one really try to match timing on two rapidly flashing lights to confirm operational lock?

Thanks, in advance, for the clarification.

David

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27 minutes ago, David Waelder said:

Do the Tentacle units operate differently? Does one really try to match timing on two rapidly flashing lights to confirm operational lock?

no, the tentacles will blink green when they are started up as master unit or successfully synced to another master, and red when they are not synched. It's really very straight forward and I like it because it's hard to mess up.

the discussion here is how you'd notice if the tentacles went out of synch and still blink green for some reason. It's a bit an academic discussion in my opinion since I've never experienced that nor heard of this happening. but if I'm unsure a quick look on the screen of the attached cameras/audio recorders or counting out numbers will work as with all other timecode boxes. 
or, as mentioned, you can hold the LEDs next to each other and if they blink in synch, chances are about 95% that they are still in synch with each other within 1-2 frames, or 5% that they are exactly X seconds out of synch because murphy had a bad day (or more like 99.9% vs 0.1% in real world).

chris

 

 

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Klaus   
On 12.4.2017 at 8:16 AM, Steve Foy said:

Just to be clear, the Blinking/Flashing light on the Tentacle (or any other Lockit Box) should only be used as a confidence check for the 'Status' of the box and/or the 'Condition' of the battery.............. that is what it was designed for !!!

 

Yes, but - and that's mine (and Constantin's) point - in reality it works much better than one would believe.

Although that's not so much of concern for devices that don't support cross jam, cross-compatible framerates (like 23.976 and 29.97ND) should not drift anyway against each other while 23.976 against 24 can immediately be spotted.

Tentacles - not supporting crossjam - will even indicate jam from a cross compatible framerate (they actually would accept) with clearly visible asynchronous blinking.

Long story short, not blinking sync is rarely a matter of whacky equipment rather than misconfiguration - and that being - clearly - visible is definitive a plus.

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engaudio   

Doesn't answer your question but here I go anyway...

I bought 2 units recently, for the price it's a no brainer exercise. Every cameraman I've worked worth has been surprised by the size and post is happy. so far, so good! I use the old fashioned method to check sync and countdown with the cameraman at the start of the day and maybe once or twice before/after rejamming at lunch. Usually I just say can we check time code? I've got XXXX minutes and xxx seconds (and so on..) No issues in roughly 15 shoot days so far apart from a F5's displays being around 1/2 a second slower, but solid in post. It may just be this op's camera though.   Overall, I'm impressed with the size/function of the product. No more "oh crap, there's too much hanging off the camera already".. 

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If you are using a 6-series SD mixer/recorder, simply plug the tentacle into it, scroll to TC Jam Menu. There you can see incoming timecode accurately compared to the internal one.

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2 hours ago, Johnny Karlsson said:

If you are using a 6-series SD mixer/recorder, simply plug the tentacle into it, scroll to TC Jam Menu. There you can see incoming timecode accurately compared to the internal one.

Thanks Johnny, the whole point of Timecode is to have an ACCURATE timebase sync system across devices............ all this talk about syncing based on flashing lights is madness......... especially when the function of those lights was never intended for anything more than a 'Status Check'.

 

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Thanks Johnny, the whole point of Timecode is to have an ACCURATE timebase sync system across devices............ all this talk about syncing based on flashing lights is madness......... especially when the function of those lights was never intended for anything more than a 'Status Check'.

This may all have been a big misunderstanding. No-one ever proposed to actually sync two devices based on the lights! The idea is to check sync based on the lights. And that is, as we have now established, very well possible. But to jam-sync two devices based on the light - no.
Looking at the two lights you can only see if they are out of sync, but not by how much. If you want to that, you'd need something like the 6- series TC comparison function.

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