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Weird Streaking/slow shutter effect


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#1 grant mcphee

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Posted 13 August 2008 - 01:08 PM

Hi there,

I've just got some rushes back from filming a friends band on my bolex.

I had 4 100' rolls developed and the last one came back with a strange streaking/slow shutter effect. I've no idea what caused it. Could it be flair?

The other rolls were developed and telecined at the same time but shot on different days. The one in question was the last to be shot so I'm concerned that it could be damage to the camera as the others came out fine.

I was using a non-reflex bolex (with a 144 shutter) at 24fps with 50hz stage lights. A pan cinor zoom. The stock was '18 which had been spooled down from 400' (fine on the other rolls, except for a couple of scratches here and there). And a best light tk onto minidv
.

Here is a link to a couple of clips from the footage
http://rapidshare.co...btest2.AVI.html


I've never seen anything like that before and would love to know what caused it.

Thanks
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#2 Tim Terner

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Posted 13 August 2008 - 01:33 PM

Went to download and got this (although it is not my IP address) pehaps better making it available for download somewhere else
You want to download the following file:
http://rapidshare.co.../jacobtest2.AVI | 44758 KB

Your IP address 78.45.79.74 is already downloading a file. Please wait until the download is completed.

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#3 John Sprung

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Posted 13 August 2008 - 02:02 PM

I let it download in the background, which took 20 minutes. Then got an error message from Windows Media Player, it uses some codec that isn't available. Maybe better to supply a smaller clip in a standard format.




-- J.S.
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#4 grant mcphee

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Posted 13 August 2008 - 04:11 PM

sorry guys.

I put a version on you tube for someone to have a look at so you can see it there.



thanks
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#5 Dominic Case

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Posted 13 August 2008 - 10:32 PM

This isn't flare, it is a shutter sync problem. You are seeng the film start to pull down to the next frame in the camera before the shutter has fully closed.

This could be because:-
  • the shutter is out of sync with the pull-down claw. However, as you only had the problem on one roll, that's not likely. Or,
  • you laced the film with too tight a loop at the top of the gate, so the take-up sprocket started tugging at the film too soon.
Or some other more obscure combination of things. For example, is it possible you unknowingly altered the shutter angle for the last roll? - that might reveal a very slightly off-timed shutter that wasn't a problem with the standard shutter angle.
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#6 grant mcphee

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Posted 14 August 2008 - 03:23 AM

thanks dominic,

It's the pre-reflex model so has a fixed 144 degree shutter. I think you might be right about the loop being too tight. I've loaded this camera about 50 times and not had a problem, but there is always a first. Will be sure to be more aware that it can cause problems in the future. Or handy to know if I want that look again. I was pretty sure it was running smoothly though. Might do a test, developing a few feet at home just to check.

Had a similar problem with an acl once but rather than a slight blur I got nothing but an abstract mess. I have a phobia about loading eclairs now. At least it was something I was doing myself and not someone else's show.
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#7 Sean McHenry

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Posted 09 December 2008 - 02:09 PM

I would suspect it is identical to this link and my first rolls in my Bolex H16.
http://home.columbus...it/Balanced.htm

It is the loop formers. If you forget to open them, when the drive gear turns it is forcing the film forward when it is supposed to be steady through the gate. The shutter is still open when the film begins moving and the blur from frame to frame happens. Try a roll and be sure you open the loop formers all the way. Still gets me from time to time.

I pulled the beasts out of my K3 because the mechanism in those loosens up overt the years it seems (made of twine and a spring) and they never did seem to open fully automatically when the cover was replaced.

Don't sweat it till you check to be sure you open the loop formers. I have had great luck with mine after being diligent about that.

Sean
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#8 Patrick Clement

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Posted 09 December 2008 - 11:32 PM

I would suspect it is identical to this link and my first rolls in my Bolex H16.
http://home.columbus...it/Balanced.htm

It is the loop formers. If you forget to open them, when the drive gear turns it is forcing the film forward when it is supposed to be steady through the gate. The shutter is still open when the film begins moving and the blur from frame to frame happens. Try a roll and be sure you open the loop formers all the way. Still gets me from time to time.

I pulled the beasts out of my K3 because the mechanism in those loosens up overt the years it seems (made of twine and a spring) and they never did seem to open fully automatically when the cover was replaced.

Don't sweat it till you check to be sure you open the loop formers. I have had great luck with mine after being diligent about that.

Sean

Yeah I thought the same thing.
I think on some of the models, you cant even close the door unless you release the loop formers.
It think one of mine allows it to shut and one doesnt.
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#9 John N Campbell

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Posted 21 December 2008 - 06:47 PM

I'm pretty sure this streaking is due to the pressure pad not being seated properly. The footage looks a little soft in the focus as well as being streaked. This would indicate that the film was not moving through the plane of optimum focus because the pressure pad wasn't snuggly clicked into place. Forgetting to open the loop formers is also a good possible explanation provided that your model is not like mine which has a fail-safe feature which, if you forget to open the loop formers, will do so when the camera door is closed.
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