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Bolex EL with Crystal Control Unit: how do I check it?


Jurjen Versteeg

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Hi there,

I just got my Bolex EL running all fine and actually got my hands on an original Crystal Control Unit. It’s running 25fps, which is perfect for me. 
Now, I hooked it up with the 7-pins Tuchel cable, like the Bolex manual described, and set the dial to CRYS. 

But how do I know and can confirm if it does actually run on crystal sync? It doesn’t give any feedback with an LED light or something…
It also runs on CRYS with the unit is not connected.

Just want to be sure if I’m going to shoot a lot of footage with it.

Thanks!

 

 

Edited by Jurjen Versteeg
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a strobe light would be the easiest way to check. run the camera at crystal and use the strobe to check if the shutter looks like running stable or at least close to stable. the strobe should be 25Hz or 50Hz of course if the crystal speed is 25fps

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it will not show clearly on film, you will see it best if watching the rotating camera shutter with bare eyes under the strobe light. If the crystal sync works and the strobe light is 25Hz or 50Hz, you should see the shutter "staying still when the camera is running" because on every flash of the light the shutter is in the same relative position if the shutter rotates at the same speed than the strobe light blinks. it is a similar effect than film the wheels of a moving car, at certain rpm they seem to slow down and stay still for a second and then starting move again in the opposite direction. 

A 50Hz fluorescent might work for the tests, never tried that but I assume one could see the effect with it too.  

If you sometime need a precise crystal stabilised strobe light I can make one for you when having time from other projects ? 

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I have an app for my iPhone called "video tachometer" that can do the same thing through phone camera frame rate trickery.  You watch your camera shutter through the live view in the app and change the speed dials until the shutter seems to be stationary, then that's your frame rate.  (Or a multiple of it depending on how the shutter works - for instance on my Arri 16S with the bowtie shutter, the indicated rate is twice the frame rate because there are two frames for every revolution of the shutter.)

Duncan

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