Frame accurate motion control help

[Tom Mitchell]

Good Day all.
I got a shoot in about a week prior to which we should have a test day.

This is a motion control shoot. Currently I don’t know what rig we are using. When I find out I shall update.

I have done some time laps and motion control before but I’m not super experienced with it, and I would appreciate advice.

The shot is in a shopping center first taken in time-lapse then again with the talent in real time. The two shot will be merged to have the background sped up and flying by.

This issue is putting it in to practice. I have been asked for frame accurate blending if possible.

First I plan on using the motion control rig to trigger each frame of the camera. I know you can do this by going in to time laps mode and selecting [Enable-ONE-SHOT (setting shutter speed), Step Print-1 and Burst type-UNIQUE) The enable the AUX to record for the remote trigger.
In theory this should work. Though I don’t know what the delay is between triggering the camera and acquiring the frame, it should be instant?

First question is, is it instant? or at least is the delay at least constant one?
How fast can you trigger the camera before it wont trigger or throws a wobberly?

Also having done some 3D work and using a trigger to fire 2 camera at the same time still results in the two camera start run times to be different (this wasn’t as issue as we used tri level lock) but how can I get the real time stuff to be frame accurate. Will I have to trigger the camera 25 times a second (if that is at all possible?)

I was also asked if there was any way to expose for longer than 1second and as far as I know that’s the longest the red will do, unless some one knows a workaround that I don’t.

If all fails we can do it low tech style and not do it frame accurate but if you can do it right, you probably should!

Thanks in advance for your input.

 

[Charles Angus]

I would recommend discussing this with your prospective MoCo vendors, and see what solutions they have on tap...

 

[Cail Young]

When shooting timelapse you can probably let the rig drive the camera (i.e. have the mocon rig trigger each frame). However when shooting sync-speed you will probably need the camera to drive the mocon (i.e. feed the mocon rig the sync signal from the RED ONE and use a bloop light for sync).

EPIC has a frame pulse input, but until then you're stuck with running the camera and slaving the mocon rig. The fastest the GPI trigger will run is around 4-5fps from memory.

 

[Tom Mitchell]

I would recommend discussing this with your prospective MoCo vendors, and see what solutions they have on tap...

Indeed I shale have a word with them once I know who they are, should be after Easter weekend, but it was them who asked the question via the DoP to me.

And since my question was about the what the camera can do and not the MoCo rig. i came here to find people with experience doing this, I going to test it all my self with the Moco guys, and if no one can help I will at least post if i find any solutions to help others. but it could save Alot of time. If some one already had done it before.

 

[Tom Mitchell]

When shooting timelapse you can probably let the rig drive the camera (i.e. have the mocon rig trigger each frame). However when shooting sync-speed you will probably need the camera to drive the mocon (i.e. feed the mocon rig the sync signal from the RED ONE and use a bloop light for sync).

EPIC has a frame pulse input, but until then you're stuck with running the camera and slaving the mocon rig. The fastest the GPI trigger will run is around 4-5fps from memory.

Thanks Cail for your response that's really helpful. just a further question...

when you say the camera drive the rig could you explain? would i be running time code out of the camera in to the rig to do that?

 

[Michael Romano]

I've used the Talon MoCo system before for similar shots and it worked great. The RED will not do an exposure longer than one second - No deals there but depending on what you're shooting that can be ok. Clouds look good but trees in the wind tend to jump a bit. We were shooting in the daytime so there was plenty of light to work with.

Essentially we created a move on the Talon computer at regular speed with the talent and shot it. Afterwards we shot again at half speed using time lapse RED functions. By doing half speed all our calculations were divisible by two. It works for that application but it needs to be tested for your particular needs before the day.

Afterwards we assembled in AE. Don't forget to set aside time for roto! As the exposure changed (Clouds etc..) in our TL the characters no longer quite matched so some finesse was required. In hindsight, a green screen might have been a better way for us to capture the talent but the budget didn't allow for it. It sure looked frame accurate but I'm not certain that it REALLY was even though our numbers added up. It was also a pain to find the true starting points of the move to sync them together.

We didn't use any external triggers for the time lapse, just the internal menu abilities, so I can't offer advice in that realm. Charles Angus is on to something, ask the vendors when you know what you'll be using.

For a total day of headaches, but longer exposures, try matching the frame with a DSLR attached to a trigger. You might have luck with a Nikon DSLR and Nikon mount with the same lens on the RED for the regular speed shot - Pan and scan likely required! I've never tested that but if you do it, I'd love to hear how it went down.

Best luck!

 

[Tom Mitchell]

Thanks for your response Michael. We might resort to the method you suggested. But we really want the frames to be taken at the same place in the track which will make for considerably less intense roto-scoping, and avoid drifting towards the end. we are inside so changing light shouldn't be a issue and use of ND's (+HM) to keep the exposure the same with out changing the DoF.

as for matching up the shot, a bloop light will be the way we can do that, suggested by cail young.

His method of the camera drivng the rig (for real time) sounds promising, but how you set that up I'm not entirely sure but that's a conversation i can have with the moco guys.


A method, or work around I just thought of to get around the 1 second exposure.

in time laps you can use burst mode, and take unique frames so 2 frames taken for 1 second at 360 (1/1) shutter fired strait after another, could be blended in AE with say the 'Add' type layer blending, adding exposure and blur to the equivalent of 2sec exposure. Any one tried that?

you could export the R3D in to stills separate the odd and even frames using a batch process then import them in AE as two sequences, then apply the blend. If i got time on test day I might try this out.

Do you know if there is an delay in the TL trigger mode from triggering the camera to capturing the frame?.

We have looked in to the DSLR option, but as you said there more headaches, than worth it.

Thanks again for all your responses keep em coming.

 

[Cail Young]

when you say the camera drive the rig could you explain? would i be running time code out of the camera in to the rig to do that?

Most mocon rigs can be fed a video sync signal (either trilevel HD or you can use a downconverter to get SD blackburst). The mocon rig will then be frame-accurate with that signal.

 

[Tom Mitchell]

Thanks Cail, Your a star.

 

[Stephen Williams]

Most mocon rigs can be fed a video sync signal (either trilevel HD or you can use a downconverter to get SD blackburst). The mocon rig will then be frame-accurate with that signal.

Unfortunately the output from RED is different to other video cameras. Until such time as shutter sync is fully incorporated like with the F35, there will be extra work in post making multi passes match, as they will only be similar & not exact. In many instances it will be good enough, others it will be a major pig. Shooting non sync speeds is am issue, I would test first. I still mainly use 35mm for MoCo.

 

[Tom Mitchell]

as far as i know you can get shutter sync on the red, otherwise 3D would be impossible, though i think that's achieved through the USB connection?

 

[Stephen Williams]

as far as i know you can get shutter sync on the red, otherwise 3D would be impossible, though i think that's achieved through the USB connection?

There is no shutter sync on Red. By shutter sync I mean a pulse that occurs at a predetermined point in the exposure, regardless of the FPS the camera is set to. It's a standard feature of film cameras, the Arri D21 & Sony F35. It's promised for Epic.

Could you explain what you mean by 'otherwise 3D would be impossible' I don't see any connection.

 

[Cail Young]

In many instances it will be good enough, others it will be a major pig. Shooting non sync speeds is am issue, I would test first. I still mainly use 35mm for MoCo.

Every test I've done with video speeds (i.e. 25 and 29.97) the particular mocon rig we've had contact with was able to slave precisely every single time.

That said, yes, offspeed is an issue - until EPIC!

 

[Tom Mitchell]

With 3D you need to make sure both cameras shutters are in phase (firing at the same time), otherwise you get horrible looking 3D and the more movement in the frame the worse it looks. since the brain sees any difference between the two eyes (cameras) as a 3D artifact, and if the difference is temporal, it breaks the 3D illusion. Thus making camera with out the ability to lock the shutters can make something that a few people might call 3D, it makes for extremely unpleasant viewing.

I worked on a few 3D jobs, where this was achieved with tri-level lock. I would then check each roll to make sure the shutters where in phase, and 98% of the time they where. It also supported several frame rates 24,48,96 all producing good lock.

But I have herd that some body's just wont work with one another and some times the shutter can be up to 10px out from the other.

The connection being that one camera was some how telling the other camera sync information.

Perhaps i'm confused on the type of signal being produced here, all i know is it seem to be working.

 

[Stefan Christou]

A method, or work around I just thought of to get around the 1 second exposure.

in time laps you can use burst mode, and take unique frames so 2 frames taken for 1 second at 360 (1/1) shutter fired strait after another, could be blended in AE with say the 'Add' type layer blending, adding exposure and blur to the equivalent of 2sec exposure. Any one tried that?

There is absolutely no reason that would not work great. The same thing is applied in the "slow shutter" effect on Sony cameras (but in video mode).

I wonder if someone has tried this as a plug in? If one made past frames expose less than more recent ones you could get a pretty good trail effect. Perhaps a logarithmic scale would work best, or maybe linear? Worth trying to find out.

Now if only I had the programming skills to build that....

(bit off topic, nothing to see here, move along)

 

[Mike Harrington]

as long as your firing off 2 different shutter speeds that would work....you could make a semi 'HDR' out of them

but if it's the same shutter speed you are not capturing any different information...and you may as well just duplicate the layer...

 

[Tom Mitchell]

Well I was having a conversation with one of my colleges at 4Klondon. and they seem to think it had potential, but what might cause a problem, is that of the photsight read time. though the sutter says it's 360, there is a moment where the photoshight is read then reset.

I thought that this would be so quick that it would be in-perceivable. so the only way i could think to test it and shoot say a spinning fan and to see if there was a gap in the blur once the frames had been blended. but als I'm busy and won't get hold of a red that i can play with for a bit, but when i do I will post the results. unless some one elce beats me too it.

The HDR option I had thought off, intact that's where the idea came from. since you cant get the camera to fire off two shutter speeds, the work around would be a mirror rig with the camera lined up over one another. each with different shutter speeds (Though through a mirror rig you will inherently loose a stop of light for each camera) and it becomes a point where the benefits don't away the effort/cost.

but alas the Epic/scarlet will alow two shutter speeds giving HDR....seems to be a theme here on this thread. sounds like i need a epic now do do all this stuff.

 

[Cail Young]

Well I was having a conversation with one of my colleges at 4Klondon. and they seem to think it had potential, but what might cause a problem, is that of the photsight read time. though the sutter says it's 360, there is a moment where the photoshight is read then reset.

Correct - 360 shutter is really very-close-to-360-but-not-quite...

However we've done a show with light painting where the FX crew automated connecting the light traces and it worked very well with a "360" shutter.

 

[Tom Mitchell]

Correct - 360 shutter is really very-close-to-360-but-not-quite...

However we've done a show with light painting where the FX crew automated connecting the light traces and it worked very well with a "360" shutter.

and once blended, the light streaks had no gaps even at the points where there was a lot of movement?

Think we might be on to something here fellers. So it seems with some work around we can do frame accurate motion control recording with exposures longer than a second. so now i recon you could do 10second exposures since that's the largest burst you can do on the red. though i wouldn't think of it a getting more light and there for more exposure but rather the motion blur of 10seocnds. because if you do a additive blend you would also be adding noise, or at least I'm assuming you would.

Still I'm eager to play with this.

 

[Tom Mitchell]

I thought I would Update this and let you guys know what we did.

Sp after discussing the options, and time + budget we had to do tests we decided to go down the DSLR option and not go frame accurate as it turned out not to be so critical with the moves we where doing. So we shot real time pass with green screen behind the subject and then again time laps.

Here is a behind the scenes video, I took. The DP shoved his 5D in my hand and said get this, hes posted it up so i thought i would share it.

in the Video we are shooting the real time pass, 1 of 5 setups we shot in the day.

The camera was a Cannon 1D mk4. With the most annoying fiddly Prosumer accessory ever. It was a pain to build the camera, and to change a lens you almost had to take it all apart. I was thinking, whilst cussing with this camera, if the epic was out when red said it was coming out it would be sitting on this rig right now.

we did use a boop light though, Thanks cail. (you will see it being held in front of the camera b4 the move)

enjoy

http://vimeo.com/10923611