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Bolex shutter problem


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#1 Zachary Vex

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Posted 23 September 2006 - 08:51 PM

I recently picked up a Bolex body that has a single c-mount which seems sturdier with my Angenieux 12-120mm than a turret, which I have to lock down. I was thrilled to get it for about $40, but in examining the camera, I've discovered that in "T" mode doing single-frame exposures, the shutter turns and stops halfway across the frame when it's supposed to be open!

Is there an easy remedy for this, or has something serious gone amiss? will this affect normal exposure, or is it possible that the shutter might be open during film movement?
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#2 Nathan Milford

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Posted 23 September 2006 - 09:50 PM

I recently picked up a Bolex body that has a single c-mount which seems sturdier with my Angenieux 12-120mm than a turret, which I have to lock down. I was thrilled to get it for about $40, but in examining the camera, I've discovered that in "T" mode doing single-frame exposures, the shutter turns and stops halfway across the frame when it's supposed to be open!

Is there an easy remedy for this, or has something serious gone amiss? will this affect normal exposure, or is it possible that the shutter might be open during film movement?



Sounds like the shutter timing is off. The shutter is probably out of synch with the claw, thus causing the film to have streaks down the frame as the film is not covered during it's pulldown.

Send it to a professional, get it cleaned, lubed and adjusted... or better yet overhauled. For $40 bucks... you're going to want to throw a couple hundred into it... otherwise you just wasted $40 bucks.


- nathan
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#3 Bernie O'Doherty

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Posted 25 September 2006 - 08:28 PM

Hi, Zachary,

It's possible that your film could be running properly (i.e., with proper exposure) even if your I/T timing is off. There is a window where the mechanism for the I/T can be off kilter while the claw/shutter timing can be on. A film test will show you if that's the case with your camera. It may very well need to be retimed and at least cleaned and lubed (a $40 purchase price implies that servicing may have been in the distant past!), but the film test ought to give you some answers.

I'm curious about which model you have. 8mm Bolexes generally have fixed C-mounts instead of turrets.

Cheers,
Bernie
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#4 Zachary Vex

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Posted 25 September 2006 - 08:42 PM

i imagined there might be a window like that. thanks for the support.

i wish i could tell you what model it is! the metal tag that indicates the model number is missing, with only the old dried glue to indicate it was ever there. it takes single-perf film (one row of teeth), it has a film footage/frame counter, runs 12 to 64, and has a metal plate on the front with suggested exposure ranges for 10-20 and 25-50ASA on it (at 16i/sec).

say Bernie, did you see my other question about lens coverage on a modified K100 (super 16mm)? do you have an answer for that?
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#5 Nick Mulder

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Posted 25 September 2006 - 11:41 PM

Sounds like the shutter timing is off. The shutter is probably out of synch with the claw, thus causing the film to have streaks down the frame as the film is not covered during it's pulldown.

Send it to a professional, get it cleaned, lubed and adjusted... or better yet overhauled. For $40 bucks... you're going to want to throw a couple hundred into it... otherwise you just wasted $40 bucks.
- nathan


I agree - but if you want to save the money try the instructions here:

http://www.sci.fi/~a...to/s16/s16.html

...they cover this topic, and depending on your mechanical ability you might be able to fix this problem for $0

putting the bolex into hand crank mode and slowly winding the claw whilst observing the shutter can help immensely also, rather than the speed of single frame...

It's an adjustment that must be made everytime you open a Bolex, I still find it frustrating but you do learn a lot ...
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#6 Zachary Vex

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Posted 26 September 2006 - 12:21 AM

wow, what a wild site. i wouldn't want to take apart a Bolex and make it S16mm myself... who knows if hot glue is stable at different temperatures and humidities? insane!

thanks for the tip. i'm getting the camera right now and looking, one moment...

and... it's perfect. the shutter closes, the claw inserts and grips, it pulls down, it retracts, the shutter opens.

thanks so much! i simply let the wind run down, then wound it a few degrees (maybe 10) and held the crank while watching the mechanism turn with the pressure plate removed.

excellent help! thanks again!
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#7 Robert Hughes

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Posted 26 September 2006 - 02:55 PM

Alternately, check to see if the variable shutter is set to 90 degrees; it's possibly half closed.
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#8 Zachary Vex

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Posted 26 September 2006 - 03:14 PM

i don't think the bolex has a variable shutter. it looks solid to me.
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#9 Nick Mulder

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Posted 26 September 2006 - 06:00 PM

thanks so much! i simply let the wind run down, then wound it a few degrees (maybe 10) and held the crank while watching the mechanism turn with the pressure plate removed.


yep, thats another way to do it, fiddly and hard to describe tho !

and re. the shutter angles - Robert is correct that these adjustments must be made with the shutter at the full 130deg if you have the variable versions
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#10 Nick Mulder

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Posted 26 September 2006 - 06:11 PM

excellent help! thanks again!


Forgot to mention tho - your cam might work ok running on I in terms of having no streaking in normal running but you still have the issue of the T exposures being partially obscured.. You need to find the small zone where your T exposures and your normal running mode are correct if you want both functions to work...
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#11 Zachary Vex

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Posted 26 September 2006 - 06:34 PM

i've never used T exposures. i'm not into animation or night sky photography now... and luckily i have another Bolex that works properly in T mode (although it has a turret, so i'd have to use my old and not-so-special primes.
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