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16mm light leak


Chloe Charlton

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Hi everyone, got some test footage back and there's this light leak happening in the footage. Very regular but can't see an obvious pattern. I've attached a clip - sorry very low quality as I can't upload a larger file size - wondering if anyone's able to figure out what the cause is? It's filmed on a Reflex Bolex and I was playing with filters/masking at the time, however light leak shows on footage where only empty filter holder was inserted. Thanks in advance! 

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Static electricity can cause pretty similar very short and random flashy streaks which come from one side of the roll and are blue-ish, very localized and relatively small and defined.

There is other possibilities too but because the flashes are very short and visually very similar than the ones I have got from static discharge it is possible that at least part of them were caused by static.

Did you spool the film by yourself and if so, did you use some kind of gloves when doing that, possibly even touching the moving film roll to for example add tension to it? one of the easiest ways to get tons of static to the film is to use rubber gloves, for example nitrile gloves when winding the film to spool. Other possibilities too to get enough static to damage the film like this but rubber gloves are especially bad for starters...

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As the flash also occurs outside the image it can't be to do with the filter slot.  I'm wondering if maybe there's a door-leak near the gate area, perhaps coincidental.  Does it still happen if you black tape up  the join?

Or is there a hole for an external magazine on top ?

Edited by Doug Palmer
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Check the seals at the top and bottom of the gate, it’s as though there is a crack letting in light that is within the loop area. Got a photo of the camera gate area?

Was the camera recently serviced or modified?

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Static electricity when winding film may create more of a visual effect like a variable area sound track as a faint blue stain on prints from neg. My money would be on the following, a light leak where the front assembly fits into the maincase or damage to a small enclosure for a tiny sync lamp in the front of the camera body, lower right as viewed from the front.

In regard Dom Jaeger's suggestion, I experienced light leak with an old H16 in those joints at the front after a desperate dismantlement to deal with water entry. My cure was fairly primitive at the time, a thin layer of clear Tarzan's Grip over the seams inside the case, blacked over with a felt tip pen. The leak was very faint and only occurred when the camera was at rest and marked stationary film.

It is over 30 years ago so my memory is vague. I think the leak occurs where those seams are exposed by a small clearance where the door overhangs. 

Whether I was on the right track or not I do not know. Whichever, the problem went away.

Edited by Robert Hart
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Does the flash occur a short distance from the start or (possibly) end of a shot ?  If so it's probably a light leak somewhere, only happening during the long time the film is at rest.  By gauging that distance it's usually  possible to find the spot.  The Bolex doesn't have a fool-proof light seal unless kept in tiptop condition  IMHO.  I've more than once had issues and generally tape the lid for peace of mind.

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Thanks for all your generous responses!

I realise my original post was written a little misleading - the leak is happening with filters and with an empty filter holder as well. It happens all the time, although is much consistent with single frame shooting (occurring on almost every frame) compared to continuous filming.

The camera was very recently serviced - this was a first roll shot since the servicing and didn't spool this film myself so wonder if static if unlikely? There's no attachment for an external magazine and I'd taped all around where the front fits onto the main body with black insulation tape, except where the gate is as this isn't as easily taped up.

Does the sync lamp you're speaking about Robert refer to no38 on page 4 of this booklet? https://film-media.dartmouth.edu/sites/department_film.prod/files/department_film/wysiwyg/bolex_h16_rx-5_sbm_manual_ocr_copy.pdf

IMG_20230313_090240346-min-min.jpg

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Your photo is too dark to see the seals around the gate, but after a service where the front has been removed the seams where it joins above and below the gate should be sealed with a light proof compound. Also the join where the compartment floor meets the body, at least around the front side. 

You could try putting a strong torch inside the compartment, closing the lid and sitting with the camera in a totally dark space for a while. Once your eyes adjust you might see a glow coming from somewhere.

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This is where the light leak occurred with my old Bolex H16 non-reflex. The light bands only occurred when the film was at rest. During motion there was not enough light leaked in to cause a problem. In daylight outdoors, a timelapse would be likely to be spoiled by banding.  

POSSIBLE BOLEX LIGHT LEAK.jpg

Edited by Robert Hart
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2 hours ago, Robert Hart said:

This is where the light leak occurred with my old Bolex H16 non-reflex. The light bands only occurred when the film was at rest. During motion there was not enough light leaked in to cause a problem. In daylight outdoors, a timelapse would be likely to be spoiled by banding.  

POSSIBLE BOLEX LIGHT LEAK.jpg

To me this does seem a likely cause, if not enough light-proof compound was applied after your service perhaps.  If you examine your single-frame material on a lightbox, you can determine which join is maybe leaking.

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