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Problems with my Bolex


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#1 Eugene Lehnert

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Posted 28 January 2006 - 12:09 PM

I just got back a few rolls of film and my footage has a lot of Edge fogging and the right and left sides, along with some minor flickering.

Most of the fogging occurs on the right side. Footage shot during the day definately has a lot more edge fogging than the footage shot at night. I'm assuming that this is some kind of light leak? Is the image flipped when it passes through the lens? Is the leak coming more from the left side of the camera or the right? Could it be the filter? I am using a Super16 converted SBM bolex.

Also, I have some slight flickering in the footage. I was running the camera with a crystal sync Tobin motor. I didn't receive any indication that the film was not running at full speed as the sync alarm never lit up. Could this be a shutter issue inside the camera?

Any advice would be appreciated.
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#2 Robert Hughes

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Posted 28 January 2006 - 01:40 PM

Do you have a filter key? Sometimes light leaks in through an empty filter key slot and fogs the film. If that's in properly, the door may be warped. Try taping the door and shoot outdoors in the day.
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#3 Eugene Lehnert

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Posted 29 January 2006 - 11:18 PM

I have a filter key. It was in as far as I know. If the leak appears on the right side of the image is it coming in through the right side of the camera?

Could the flickering be related to this problem?
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#4 gregorscheer

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Posted 30 January 2006 - 12:05 AM

I had a similar problem with an EL (which does not have the filter slot) one thing is that if you have the light coming from behind you as you shout and you do not have your eyes on the viewfinder you should close it because the light coming through the viewfinder can get to the film.

I'm also trying to figure out what happened. Unfortunately I am not sure whether it is the filmstock that had been left in the Mag a few month and that was recanned to begin with.

Will keep you posted if I know more
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#5 Eugene Lehnert

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Posted 30 January 2006 - 01:39 PM

I always close my viewfinder. Maybe there is a leak in there though? It definately is on the sides though. I would think that would just wash out the image overall.
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#6 John Pytlak RIP

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Posted 30 January 2006 - 01:55 PM

I'd suspect the edgefogging occured during loading. Where did you load the camera? In "subdued light" or a darkroom or changing bag having "total darkness"? In Super-16, the edge of the film is closest to the image on the right hand side of the image, so any edgefog shows there first.

http://homepage.news...ex_loading.html
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#7 Eugene Lehnert

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Posted 30 January 2006 - 06:14 PM

I thought that might be an issue as well. It's just that I did load it in subdued light. I was shooting at night. And I have shot lots of film before, but that was on a regular 16mm bolex so I may never have noticed it being a problem. But it still doesn't explain the flicker effect I'm getting. I shot two rolls with this camera before the shoot and both came out fine. I guess I have many tests to perform.
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#8 lluis

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Posted 31 January 2006 - 02:01 PM

Film fogged at the edges: bad load or old stock or light leak from the camera lid or from inside the camera (disappeared black cement which unite the platine).
Flicker (probably visible only with cristal speed): excess of play in the shutter gear or others gears, or lack of lubrication.
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#9 Eugene Lehnert

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Posted 31 January 2006 - 02:56 PM

Why is the flicker only seen with at crystal speed?
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#10 lluis

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Posted 31 January 2006 - 08:34 PM

Why is the flicker only seen with at crystal speed?


Because at crystal speed the movement of the axis motor "force" all the gears to be controlled "up and down", to let the precise speed controlled. If there is a minimal play between gears it originates a internal vibration which causes the flicker. If the camera run by the mechanical power the moviment is always "up" and probably the flicker doesn't exist.
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#11 Tim Carroll

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Posted 31 January 2006 - 08:40 PM

Because at crystal speed the movement of the axis motor "force" all the gears to be controlled "up and down", to let the precise speed controlled. If there is a minimal play between gears it originates a internal vibration which causes the flicker. If the camera run by the mechanical power the moviment is always "up" and probably the flicker doesn't exist.


That is really interesting. When I had an EBM that flickered something terrible, it only did it when hooked up to the Tobin crystal sync I had. When the camera was just running at the EBM's non-crystal 24fps I had no flicker. And when looking at the shutter with a strobe and freezing the leading edge, it looked like it kept falling forward and then catching back up. And since I replaced all the suspect electronics on the boards in the camera and that still did not fix the problem, I bet it may have been gear backlash.

-Tim
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#12 Eugene Lehnert

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Posted 02 February 2006 - 10:26 PM

So what is the point of using a crystal speed motor on my Bolex? How can I avoid this? Would a simple overhaul of the camera suffice?
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#13 Robert Hughes

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Posted 03 February 2006 - 04:47 AM

If the gears & bearings are dry, the motor has to force the mechanism to operate. Lubrication during overhaul is always a good plan.

But it's possible the flicker doesn't have anything to do with the camera itself. What lighting conditions are you shooting under? I've shot under mercury and sodium vapor lights that flicker something awful, the rate of flicker varying with how far off 24 fps and at what shutter angle my camera happened to be set. If you see flicker in daylight scenes, that's definately camera related.
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#14 Eugene Lehnert

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Posted 03 February 2006 - 11:56 AM

Aye. The flicker was during the day and night. It's all over various footage that I s hot. Overhaul it is!
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