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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Red One genlock tests for 3D....

3D Sync - error ?

3D Sync - error ?

If the sync doesn't lock with fast frame rates and narrower speed shutter...

Being in the cue for more than 2 Scarlets (2 x 2/3" + 2 x S35 + 2 x FF35 more exactly) in the next future, I'd like to know how this can be solved.
Click to expand...

Scarlet and EPIC use a totally different method for synchronization between cameras.


On the original subject, if there is a sync issue between two RED ONE cameras, then

a) we'd like to verify that is in fact so, and the error is not caused by system level issues.

b) if there is an error, create a fix for that.
 
Nice to know and good to check you are aware.

On the other side -- and now I also address the subject to my inner circle, the SI solution has only variable frame rates (85fps) up to 720p (or 150fps @ 540p); even though the better sync performance (beyond the 24/25fps with a 180º shutter where the issue is more irrelevant) as fair conclusion from the tests verified by so many different sources.
 
Don't know if this has anything to do with it but -

I was just a motion control shoot. We were shooting 3 passes at 3/fps - and we were unable to sync it (or match it on the timeline). - the motion control operator something about the RED always outputs 50hz no matter what framerate or shutter you use. (in PAL land).

As a fix we shot it 25fps and everything synced and worked out fine.
 
Sync questions

Sync questions

Well to be Genlocked you would need to be at an integer multiple of RS-170 tri-level sync. In "PAL" land that's a multiple of 25 fps - 25 / 50 / 75

Operating a RED ONE on MOCO at 3 fps or other totally unrelated speed to Genlock, you need to be using GPIO handshakes to step frame record.

The 50 Hz comment sounds like he's referring to the HD-SDI output. At 720p there are only two SMPTE approved frame rates, 50.00 and 59.94.
 
Sync test results

Sync test results

Emanuel A. said:
Nice to know and good to check you are aware.

On the other side -- and now I also address the subject to my inner circle, the SI solution has only variable frame rates (85fps) up to 720p (or 150fps @ 540p); even though the better sync performance (beyond the 24/25fps with a 180º shutter where the issue is more irrelevant) as fair conclusion from the tests verified by so many different sources.
Click to expand...

The key word in my comment "if there is a sync issue" is the word IF.

No issue can ever be resolved if there is no evidence given, so if you have some test results please share those with us.


stuart@red.com
 
Stuart English said:
The key word in my comment "if there is a sync issue" is the word IF.

No issue can ever be resolved if there is no evidence given, so if you have some test results please share those with us.


stuart@red.com
Click to expand...
Is there any reference on frame start and shutter start delay when system uses the Genlock synchronized shutter?
I could not find anything in the RED manuals published on line.
Since the RED camera is the first and only that allows gen-locking shutters then I would like to advertise this fact when presenting my designs of true off axis geometry RED based stereoscopic rigs.

Please advice.

Mathew Orman

For state of the art stereoscopic vision systems with: eyestrain free, distortion free and realistic immersion stereoscopic experience contact me
at:
http://www.tyrell-innovations-usa.com/
 
For what it's worth: I use multicamera shots with the AJA gen and the timecode daisy chained through the cameras. My clips are typically between 1 and 2 hours in length. I have tested the sync by using the electronic slate at the beginning and the end. I also send sound to both cameras and never get any audible echo, so I feel confident that they do not drift long term even though they may not lock to the same oscillator cycle in the sequence.

Dave
 
Stuart English said:
The key word in my comment "if there is a sync issue" is the word IF.

No issue can ever be resolved if there is no evidence given, so if you have some test results please share those with us.


stuart@red.com
Click to expand...

I am not an engineer, it has been the engineering part of my team who has alerted me on the facts. As posted. But Pedro Guimarães has found the same results as both cameras in Lisbon (my engineer's information). Confirmed by others along the thread.

Unless, there may be any error by default in the sync methodology. However, in this case, it would be useful to know where? Aren't these results and subsequent information posted by Pedro enough in order to find an end for the current subject? I believe this cannot be a Nouvelle Vague plot, not even should be ;-)
 
We need accurate data to evaluate the issue.

Accurate measurement of any possible sync offset is needed. If only to clearly demonstrate the existence and extent, if any, of the issue.

Sadly I do not have access to two REDs to test this myself but what is needed is a test similar to Pedro's earlier post but using a known and reliable clock/time/frequency source as subject. That will give a decent bit of information on the impact of any sync issue and more detailed electronic measurements alongside procedual notes would also help a great deal.

Pedro, regarding the 1/2000th shutter test:

Between camera L & R images, did the fan blade's stay consistently out (remained at the same angular distance from each other) or did they "phase" (the blade's angular distance changed) over time?

JohnF
 
icester said:
Is there any reference on frame start and shutter start delay when system uses the Genlock synchronized shutter?
I could not find anything in the RED manuals published on line.
Since the RED camera is the first and only that allows gen-locking shutters then I would like to advertise this fact when presenting my designs of true off axis geometry RED based stereoscopic rigs.
Click to expand...

The red is far from the first to offer this.....certainly not the only. Video cameras in various forms (on the higer end) have been offering this for decades. Usually for multicamera situations.

JohnF said:
Pedro, regarding the 1/2000th shutter test:

Between camera L & R images, did the fan blade's stay consistently out (remained at the same angular distance from each other) or did they "phase" (the blade's angular distance changed) over time?

JohnF
Click to expand...

I don't remember well but I think it's constant which is why I was hoping adjusting the phase in 1 degree increments would be enough.

Jonas said:
What did you guys use as generator?
I was not successful to synch with an AJA GEN10 HD/SD Sync Generator.
Click to expand...

If you read my orginl post carefully your will see I normally use Gen10 but I also tried a Deneke.

Samuel Martin said:
In a 3D shoot last week we sucessfully genlock 2x red cameras at 100fps on 25p base rate consistently and with the TC generator not shifting at all either. Camera would not genlock any higher than that though.....
Click to expand...

Sorry but I highly doubt your statement. Show us Proof of this.

-------------------------------

UPDATE:

I was asked to help perform some pre-shoot tests for a big 3D shoot a month ago. I went over to Keslow camera and had an opportunity to perform my same genlock tests on 2 MX sensor cameras.

I was curious to see if the results would be different. Unfortunately I got the same results as always. So in case you were wondering the RED one with a new MX sensor does NOT change anything in regards to gen/sync/phase lock....
 
Is the out of sync shutter noticeable when viewing the footage in any circumstances other than a frame by frame examination?
 
footage shot at 120fps it is very noticeable...
 
Pedro Guimaraes said:
footage shot at 120fps it is very noticeable...
Click to expand...

In our tests using timing strobes, sync is locked on red one when using the gen 10 and normal frame rates like 23.98, 24, 25, 30 that you can set on the source.

For higher frame rates we set it to true 24/25/30 and then do a multiple of that. Setting it to 23.98 and trying genlock at a non prefect multiple is not technically right.

I would expect some inaccuracy in varispeed because genlock only provides a handful of rates in the standard and the camera would have to make up the timing for the frames in between. Even so it seems to work really well for us.
 
I've tried all multiples of 24......this shot below that I shot for the Discovery channel 3D upfront presentation last month, shows it really noticeable(120fps)....none the less there were no complaints from the thousands of people that have seen it...but take your glasses off and you can really see it!

Your brain/eye is capable of seeing what it wants to see....doesn't mean it isn't straining itself. Also once your eyes/brain gets trained to see it....you notice it everytime.

Here is a frame grab from the shot. I will try to get permission to show a clip of the 3D version so you guys can see what I'm talking about.

Hyperstereo shot @ a 7" IA, about 390ft from subject with angeniuex rouge 30-80mm @ 80mm. 2k 2:1.-120fps Build 30 (I believe). Shot "sync'd" with aja gen 10.

vw.jpg


VIR-Virginia international Raceway, special shoot for VW TDI cup series/Discovery 3Dtv. Image property of Discovery channel/Digital incident.
 
Establishing genlock for 3D

Establishing genlock for 3D

Is there any reference on frame start and shutter start delay when system uses the Genlock synchronized shutter?
Click to expand...

If you see padlock icons in each camera's UI you are Genlocked. If you feed a common Genlock Sync source our tests show that this lock is absolute.

If you don't see these padlock icons in the UI, or if you don't have a common Genlock Sync source, then you are not locked off / at risk of being off.
 
3D Genlock - maximum frame rates

3D Genlock - maximum frame rates

In a 3D shoot last week we sucessfully genlock 2x red cameras at 100fps on 25p base rate consistently and with the TC generator not shifting at all either. Camera would not genlock any higher than that though.....
Click to expand...

That makes sense.

The camera can only lock up to multiples of the Genlock Sync frequency, so 4 x 25 = 100, but 5 x 25 = 125 and the max frame rate is 120 fps.
 
Genlock for 3D at slow speeds

Genlock for 3D at slow speeds

I was just at a motion control shoot. We were shooting 3 passes at 3/fps - and we were unable to sync it (or match it on the timeline).

As a fix we shot it 25fps and everything synced and worked out fine.
Click to expand...

So going in this other direction, you can also lock to fractions of the Genlock Sync frequency - so for 23.98 / 24.00 fps that means 12 fps, 8 fps, 6 fps, 4 fps ...

Unfortunately 25 fps doesn't divide as nicely.
 
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