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image flickers?


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#1 Daniel Carruthers

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Posted 05 June 2009 - 02:26 PM

Hey
I just shot some 16mm film, I had it transferred at Cinelicious at pro res 422
and for some reason about half way through the footage the image starts to flicker?
its goes dark light dark light, very rapidly.
could this be a defect in the transfer?
or could this be somthing in camera???
any ideas?
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#2 Charles MacDonald

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Posted 05 June 2009 - 08:10 PM

Hey
I just shot some 16mm film, I had it transferred at Cinelicious at pro res 422
and for some reason about half way through the footage the image starts to flicker?
its goes dark light dark light, very rapidly.
could this be a defect in the transfer?
or could this be somthing in camera???
any ideas?

This is where the split reels and teh rewinds come out to look at the negative.
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#3 Simon Wyss

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Posted 06 June 2009 - 02:44 AM

You shot at 24 fps I presume. At what pace are the fluctuations, I mean timewise?
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#4 Chris Burke

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Posted 06 June 2009 - 07:38 AM

Hey
I just shot some 16mm film, I had it transferred at Cinelicious at pro res 422
and for some reason about half way through the footage the image starts to flicker?
its goes dark light dark light, very rapidly.
could this be a defect in the transfer?
or could this be somthing in camera???
any ideas?


post a little clip of the offending footage on Vimeo, you know the saying, " a picture is worth a......."
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#5 Daniel Carruthers

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Posted 06 June 2009 - 10:41 AM

You shot at 24 fps I presume. At what pace are the fluctuations, I mean timewise?



Yes I shot at 24 frames
about 2 fluctuations a second.
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#6 Simon Wyss

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Posted 07 June 2009 - 12:57 PM

It appears to be interference between frame rate and lighting frequency. With a 172.8 degrees shutter opening 24 times a second you get exactly two intersections with 50 cycle mains. That would explain but you had 60 Hertz mains for the shoot, hadn't you?
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#7 Daniel Carruthers

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Posted 07 June 2009 - 03:57 PM

It appears to be interference between frame rate and lighting frequency. With a 172.8 degrees shutter opening 24 times a second you get exactly two intersections with 50 cycle mains. That would explain but you had 60 Hertz mains for the shoot, hadn't you?




I dont really know what you mean simon?
I was shooting under natural daylight, and the eclair NPR has a 180 degree shutter
can you please explain to me again in a bit more detail?
thanks man:)
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#8 Saul Rodgar

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Posted 07 June 2009 - 04:03 PM

I have had flickering problems at Cinelicious. Some shots at 24 fps with 180 degree shutter flicker for no apparent reason _ just in the middle of the reel, shooting outdoors with no extra lights, no panning or dollying, while using a fresh battery or the same battery as the shots that don't filcker, etc.

When I first saw it, it really had me wondering, but then I re-transferred the footage on a Spirit and it magically went away. I dunno what causes this, but I figure there is more than one reason why labs with Spirits (Arri Scanners, Northlights, etc) charge a lot more than Cinelicious ;) _which bang-for-the-buck is a great lab.

This may or may not be your case though, without looking at it, it is hard to say. It could be the motor, the shutter, the electricity for the lights (cycles per second) and the shutter / frame rate not agreeing, etc

Edited by Saul Rodgar, 07 June 2009 - 04:04 PM.

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#9 Simon Wyss

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Posted 08 June 2009 - 04:09 AM

I dont really know what you mean simon?
I was shooting under natural daylight, and the eclair NPR has a 180 degree shutter
can you please explain to me again in a bit more detail?
thanks man:)

Well, with that combination of shutter angle, frame rate and light pulse there should be no fluctuations, constant speed provided. It would have to be the motor running wild. Now as you say daylight the camera issue falls away. Left only light pulsation with the scanner.

Good scanners employ DC fed light sources such as LEDs on accumulators to exclude all interferences. Check on that point, insist that they explain. Sometimes also the scanner's speed is set incorrectly which will provoke that dark-light-dark-light.
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#10 Saul Rodgar

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Posted 08 June 2009 - 10:02 AM

Left only light pulsation with the scanner.

Right, or (more unlikely) somewhere else in the signal chain.

Good scanners employ DC fed light sources such as LEDs on accumulators to exclude all interferences. Check on that point, insist that they explain. Sometimes also the scanner's speed is set incorrectly which will provoke that dark-light-dark-light.

Cinelicious' telecine is a pre-LED modified tube-based Cintel Ursa machine, upressed to HD, possibly by a Terranex up converter.
http://www.cinelicious.tv/?page_id=18
http://www.cinelicious.tv/?page_id=24
The speed settings on the machine could be wrong, but that doesn't explain why some shots withing the same reel have flicker and why some of the ones after don't, unless the operator resets them as he goes or they drift after a while. These machines are old, bear in mind, so anything is possible.
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#11 Simon Wyss

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Posted 09 June 2009 - 03:05 AM

Yes, Saul, I think we're close to the thing. I'd have imagined the operator set the speed wrongly after some work. Might have come anywhere in the roll.

Good luck, Daniel!
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#12 Daniel Carruthers

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Posted 09 June 2009 - 11:08 AM

Thanks for your help guys
I ended up unspooling the last 25 feet and looked at the negative under a light
I didnt notice any flickering on the negative.
but the flickering only changes by maybe a 1/8 of a stop
so there could still be flickering on the negative,just not enough for me to notice on the negative?

one thing that makes me think it could be the camera is on every shot
the flickering starts to become more apparent as the shots progress.
that makes me think it could be a problem with the camera?

if it is the camera, could it be the batterie pack I was using to power the camera??

Edited by Daniel Carruthers, 09 June 2009 - 11:10 AM.

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#13 Bernie O'Doherty

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Posted 09 June 2009 - 03:05 PM

Daniel, Could be the rubber coupling on the camera base is slipping. Try,( until you get a replacement) wrapping a single layer of camera tape around the motor driveshaft. You'll need to separate the camera body from the motor by flipping the 4 wedge shaped arms at the camera base.
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#14 Daniel Carruthers

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Posted 09 June 2009 - 03:55 PM

Daniel, Could be the rubber coupling on the camera base is slipping. Try,( until you get a replacement) wrapping a single layer of camera tape around the motor driveshaft. You'll need to separate the camera body from the motor by flipping the 4 wedge shaped arms at the camera base.



Thanks Bernie I'll try that
do you know where I could get a new rubber coupling?
if thats the problem?
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#15 Bernie O'Doherty

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Posted 09 June 2009 - 04:14 PM

There are many ways to skin this particularly French cat. The rubber on the coupling is very thick. All it needs is way to decrease it's diameter very slightly by banding it . O rings work well. I sometimes take off the coupling and angle the spacers towards the shaft. This pulls the coupling so it grabs the shaft better. You could try Optical Electro House for the part.
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#16 Bruce Taylor

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Posted 09 June 2009 - 08:40 PM

I'd have imagined the operator set the speed wrongly after some work. Might have come anywhere in the roll.


I think you should ask Cinelicious to look at the issue. They're good people over there. When I rent gear I want clients to let me know if they experience any problems so I can fix them- otherwise I might not know there is anything wrong.

If you can't come to a satisfactory resolution or still can't figure it out, have another telecine shop transfer the offending footage. That should sort out if it's a camera or transfer issue. I mean the Ursa Diamond at Cinelicious is old, but so is your NPR.

Good luck, let us know what you find out.

Bruce Taylor
www.indi35.com
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#17 Daniel Carruthers

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Posted 10 June 2009 - 11:47 AM

Im getting a 2nd transfer done at cinelicous, so I should know in a week or so?
I'll keep you guys posted
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#18 Daniel Carruthers

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Posted 15 June 2009 - 12:01 PM

Hey
well I just talked with paul at Cinelicious
unfortunately the flicker issues where in the negative
so it was not the transfer.

The flickering occurred at the exact same moment in both transfers.
I really appreciate cineliciouse for taking a 2nd look at the negative.
Ive always liked there transfer jobs,and I plan on shooting more U16 and getting more transfers done at cineliciouse when I get the camera fixed.

I guess Im gonna have to do some tests and figure out what could be causing the flicker problems
in the camera?
luckily our editor can actually fix the flicker issues in post?:)
Im not sure how,or how long that may take,but at lease our film isnt totally ruined:)
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#19 Bruce Taylor

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Posted 15 June 2009 - 06:18 PM

when I get the camera fixed.
I guess Im gonna have to do some tests and figure out what could be causing the flicker problems
in the camera?


I have a suggestion, send it to Bernie O'Doherty at Super 16, Inc. He'll fix you up for a reasonable fee. He'll make your Eclair happy again.

Bruce Taylor
www.indi35.com
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#20 Daniel Carruthers

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Posted 29 July 2009 - 11:31 AM

Well it turns out the problem was not the camera or the transfer
it was the Battery Pack! lol
It never occurred to me that the battery could malfunction?
Im really happy it turned out to be the battery, its cheap to replace
I dont have to get any camera repairs.
And now I can start shooting more Ultra16mm :D!!
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