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Dust Artifacts


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#1 Barry Cheong

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Posted 18 February 2006 - 11:45 PM

Hi!

I've been working on a variety of student productions that we've been shooting on an Arri SRII S16. The film has been processed and has undergone a supervised transfer to Betacam. Looking at the rushes I've noticed dust and other artifacts appearing on the footage. Not all over the place and not on everyframe (not a scratch) but just the usual mix of things popping up here and there. I'm wondering how larger productions avoid this? I know a lot of network TV shows and music videos also shoot on super16 and there are no artifacts there. Is there a digital clean up process that these productions go through? Is it a lab thing? We are shooting in a studio where it's relatively clean.
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#2 David Mullen ASC

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Posted 19 February 2006 - 12:17 AM

Dust is something that comes in at every step of the process, requiring everyone to do their best to avoid it, from the film stock manufacturer, to person loading the mags, the person threading the film into the camera, to the lab, to the telecine house.

Ultmately, the final resort commonly used is to do a dust removal session after the transfer. But there is a charge for that, so the more you can eliminate it in the earlier stages, the better. Plus for straight photochemical finish to a print, non-digital, there are fewer options to remove it.

Dust obviously looks larger in smaller film formats because the image is enlarged more.

Dust has been a neverending source of annoyance to me.
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#3 John Pytlak RIP

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Posted 20 February 2006 - 08:48 AM

Hi!

I've been working on a variety of student productions that we've been shooting on an Arri SRII S16. The film has been processed and has undergone a supervised transfer to Betacam. Looking at the rushes I've noticed dust and other artifacts appearing on the footage. Not all over the place and not on everyframe (not a scratch) but just the usual mix of things popping up here and there. I'm wondering how larger productions avoid this? I know a lot of network TV shows and music videos also shoot on super16 and there are no artifacts there. Is there a digital clean up process that these productions go through? Is it a lab thing? We are shooting in a studio where it's relatively clean.


Dust particles on camera raw stock produce a black "shadow image" in the final image. Worst case is a "hair in the gate" when a fiber or dirt buildup gets attached to the aperture, and intrudes into the picture area. Cleanliness in loading (clean darkroom or changing bag) and cleaning loose debris from the interior of the magazine helps.

When the shadow images are white, the dirt particles are on the processed negative. Could have been picked up during processing or handling of the negative. Labs routinely clean the negative (solvent cleaning, Particle Transfer Rollers (PTR) or "tacky tape" cleaners) to remove loose debris picked up during handling. Telecines and printers using specular illumination are usually more critical for surface imperfections.
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#4 Phil Rhodes

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Posted 20 February 2006 - 09:57 AM

Hi,

When I shot 16mm, we ran 1200ft and there were exactly three instances where dirt or dust were visible. Only one of them appeared in the finished piece, and I painted it out in Photoshop in about thirty seconds flat.

And this was an old, old camera!

Phil
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#5 Max Jacoby

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Posted 20 February 2006 - 10:02 AM

So how did you like your film experience Phil? And most importantly who put up the £45K that allowed you to shoot film?
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#6 Barry Cheong

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Posted 21 February 2006 - 08:52 PM

Thanks for the all the responses. I have talked to my 1st assistant to try to reduce dust and debris as much as possible during the shooting process. I just noticed it quite a bit while looking at other people's rushes - although now looking closer at even larger productions you do see it every once in while though not nearly to the same extent. Is there a certain quality level/class that one must pay for better handling at the lab or transfer house? Or is it the same across the board? The school is covering all the backend post expenses so I'm not privy to that info.
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#7 David Mullen ASC

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Posted 21 February 2006 - 09:19 PM

Well, in terms of the lab, they can't really separate the rich client's footage from the cheap client's footage in order to put one through a dirtier bath -- all are equal at that stage, you all go in together. Telecine places are supposed to ultrasonically clean film before transferring it; that's why you write "prep for telecine" on the camera report and work order.
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#8 Barry Cheong

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Posted 22 February 2006 - 12:01 AM

Thanks David!
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#9 Phil Rhodes

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Posted 22 February 2006 - 10:52 AM

We were given practically everything.

Not a very reliable basis for comparison.

Phil
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#10 Stephen Williams

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Posted 22 February 2006 - 10:58 AM

Hi,

In Switzerland motion picture film is often processed to order, in about 1 hour while U wait! If there is only a small amount of film going through, there seems to be more dirt per foot than on a big run. Once when I had 25,000 foot to process I asked if they would clean the bath first. They replied 'we always do'!

Stephen
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#11 John Pytlak RIP

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Posted 22 February 2006 - 01:35 PM

Hi,

In Switzerland motion picture film is often processed to order, in about 1 hour while U wait! If there is only a small amount of film going through, there seems to be more dirt per foot than on a big run. Once when I had 25,000 foot to process I asked if they would clean the bath first. They replied 'we always do'!

Stephen


Labs running higher volumes of color negative usually perform maintenance on a daily basis (e.g., using fresh washes). A lab that runs only a few rolls a day may not perform machine maintenance as frequently. A good lab will ALWAYS run a "scratch and abrasion" test before running customer footage, especially after machine maintenance or a prolonged down-time.
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#12 Stephen Williams

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Posted 22 February 2006 - 02:22 PM

Labs running higher volumes of color negative usually perform maintenance on a daily basis (e.g., using fresh washes). A lab that runs only a few rolls a day may not perform machine maintenance as frequently. A good lab will ALWAYS run a "scratch and abrasion" test before running customer footage, especially after machine maintenance or a prolonged down-time.


John,

I fear my shoot is the scratch test!

I have to choose the labs, by the emulsion that I am shooting! Vision stocks seem to be more delicate than Fuji. 2 years ago I shot 18 rolls one weekend, 5 Kodak & 13 Fuji. All the Kodak were mildly scratched. We had 3 mags, all ran Kodak and Fuji. On the Monday we shot both stocks, used another lab without problems!

6 months later I advised a Cameraman from London not to use that Lab, he was shooting 5218. He called the lab who laughed........ some of his footage was scratched in the same place as mine! The labs response was nobody else complained........

Stephen
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