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16mm registration jitter and Digibeta capabilities for 24fps

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bear media
16mm registration jitter and Digibeta capabilities for 24fps
on Sep 30, 2008 at 2:38:32 pm

Hello,
Two things all stemming from the same issue. My partner and I recently shot S16mm for a film and had Digibeta dailies made for off-lining. We noticed a slight jitter in the shots - normal for film, but it seems to be slightly more pronounced than with other cameras. We're shooting on an overhauled Aaton camera. It's a great camera, but we're trying to chase down the source of the jitter to see if it could be another factor that is amplifying it.

One thought is that it is more noticeable in a 2:3 pulldown scheme. We suspect that our footage has been laid to tape with 2:3 pulldown, but aren't sure. We were told that Digibeta can handle 24fps and that the telecine would be just that.

Is the jitter normal? How do you get around or minimalize it? Does Digibeta handle 24fps? If so, How can you be sure that you're capturing it properly?

Sorry to come across so green, but HD is my typical shooting format, and video is my normal world. We're bridging to film finally and really want to get it right.

Thanks,
Brad


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john sharaf
Re: 16mm registration jitter and Digibeta capabilities for 24fps
on Sep 30, 2008 at 2:57:39 pm

Brad,

Sounds like sloppy registration in your "reconditioned" camera. To be sure you'd need to shoot registration test. Simplest test is to shoot detailed subject, like the classified page of newspaper, then rewind or reload film and shoot again. This double exposure will reveal any weakness in registration.

As far as the telecine; all 24fps film to tape will include the 3:2 pulldown, because all tape formats (except 24/25p in HDCAM) record at 30 frames per second (really 29.97). Your NLE will remove the original 24 if you want to create a 24p project.

The only exception is that there are specially modified video machines which run at 24p for the purpose of playing back video to be rephotographed by a movie camera.

About "getting around" the perceived problem, there really is no way other than to determine if the camera had registration issues and if so, reshoot.

It's somewhat ironic, now that HD video as progressed to the point it has in replacing film for many traditional film holdouts, for you to be going the other way. The many reasons for using HD instead; cheaper, no grain, instant confidence, simpler and faster workflow, no jitter, etc., beg the question, why?

JS





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Todd Terry
Re: 16mm registration jitter and Digibeta capabilities for 24fps
on Sep 30, 2008 at 3:07:10 pm

Well obviously, you shouldn't have jitter. The colorist or whomever is doing the actual transfer at your telecine facility should instantly be able to tell if the jitter is on the actual negative. You didn't say which Aaton you are using... some models of Aatons have registration pins, some do not. If you were using a pin-registered camera then it is unlikely that much if any of the jitter is actually originated in camera.

I'm not sure if DigiBeta can handle a direct 24fps tranfer or not without the pulldown... but I don't think that would be the problem. Discrepts in frame rate could cause some stuttery artifacts or motion "judder," but would not cause the jitters which is an up-and-down movement.

My first guess would be that it is a camera problem. If not, and if it is a pin-registered camera, then my suspicion is that the "jitter" lies with the telecine itself. Do you know what the particular hardware was?...Spirit?... Rank? A higher-end system like those which continuously move the film (rather than stopping on each frame, like a projector or camera) should not introduce any jitters, but other systems can.

It sounds like you were not able to babysit the telecine session and see firsthand whether the jitter was present before it "stuck to tape." My advice would be to get on the horn with whomever actually did the transfer and ask if he/she noticed whether the jitter was present in the signal straight out of the telecine. And if so, can they try it on another machine? If you get the same results, then chances are the jitter is camera-originated and is on the negative. It can probably be removed somewhat with some image stabilization...with varying degrees of success.


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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bear media
Re: 16mm registration jitter and Digibeta capabilities for 24fps
on Sep 30, 2008 at 4:52:37 pm

Yeah, we didn't sit in on this transfer. We're going to when we have the scans made later in the process for the final online.

The camera does have registration pins. Honestly, you have to really stare hard at the film to notice the motion. I argue that it is the nature of film, because we've compared it to S35 footage we've shot and major motion pictures. There is an inherent "breathing" in film. Ours is just ever so slightly more. It doesn't really show up on under cranked shots though.

There was no mention of any problems on the notes from the transfer. We trust the transfer house, they caught problems early on that we had fixed, and then retested with a perfect report.

We both come from video production backgrounds and were not familiar with our NTSC Digibeta decks using 24fps. I just wanted to ask in case I had missed something.

To answer the other post response in this thread:

We're mastering on HDcam SR, but we wanted the most image control possible in post so we went with film. Film is also the most forgiving in our circumstances. We're shooting a doc, and have been bouncing around the globe uncertain of the conditions we would be in. We are also shooting a little with the HVX200 and, for extremely long interviews, the Sony F900 - But 90% percent of the project is originated on film. The other reasons behind going film are purely emotional. We really wanted to originate a feature on film, and once the story came along that we couldn't stop thinking about, we started.

This issue, of the jitter, just came up when we got the dailies back on Digibeta. I wanted to ask to better inform our decisions moving forward. We may have to rent a newer Arri package.


Brad Bear
brad.bear@yahoo.com


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Todd Terry
Re: 16mm registration jitter and Digibeta capabilities for 24fps
on Sep 30, 2008 at 5:25:57 pm

I hear ya...

Do a short registration test like John suggested. We usually shoot a test chart with a cross-hatched grid on it, rewind, then double expose it. That's the gold standard test.

Film can indeed breathe a bit, but it doesn't have to... years of watching movies on the big screen has us accustomed to the slight breathing and gate weave that you see... but in those instances those are almost always projection issues, not camera issues. Watch a feature film in a digital theatre (and it seems like the majority of screens now have the Christie projectors) and most 35mm-originated features are rock solid.

Then again, of course your 16mm negative is much smaller than a 35mm neg, and any slight problem is going to be magnified by about 5-7 times. I shot lots of 16mm before moving to 35mm... then it was very hard to go back to the occasional 16mm project, where every dust speck or registration problem was seven times bigger than before.

16mm has limitations, but can be great... just depends on what you are able to squeeze out of it. Some 16mm on the boob tube looks awesome (i.e., "Scrubs," "Friday Night Lights"), and some, eh, not so much ("Walker: Texas Ranger").

You may have to indeed ditch that particular camera. If I were in your shoes and wanted to shoot film and wanted 16mm and wanted Aaton and wanted to travel very light and run-n-gunny... I'd go for an Aaton A-minima.

There are lots of A-minima rental cameras out there... or if you wanted to bite the bullet and buy one they are pretty darn cheap (well, cheap as far as higher-end full-featured silent sync-sound film cameras go). You'd have a shorter run time with the little 200' mags which might be problematic for documentary work... but they will still run almost twice as long as 400' of 35mm.


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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bear media
Re: 16mm registration jitter and Digibeta capabilities for 24fps
on Sep 30, 2008 at 5:47:03 pm

You guys are awesome. Thank you very much, and I'll try to keep you posted as this plays out.

Brad Bear
brad.bear@yahoo.com


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