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What is causing light streaks?

cp-16 light streak bow tie test

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#1 Omar Lopex

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Posted 20 July 2017 - 02:26 AM

Hi, not sure what forum this belongs in.

 

I did a very short camera test for my CP-16R. I have a CP-16A which I've shot with and never had problems, but I bought this R model to use prime lenses on it instead of the standard angenieux.

 

I have the bow-tie or butterfly model that is infamous for light streaks in the upper right corner, so I was testing for that. It doesn't look like I got any of the streaks people associate with this model (maybe I didn't have bright enough subject matter in the upper corners?)

but...

there is a subtle (but constant) flicker in the center of the frame. It looks like what might happen when you take your eye away from the viewfinder, but a camera operator of mine made that mistake once last year and I since then I always make sure to keep my eye firm against the viewfinder. 

 

Wondering if it could be because I shot at 12FPS (to save film stock and development/telecine $$)? I did forget to tell the lab that I shot in the slower frame rate. Could that affect the way they telecined it and caused flicker during telecine that aren't on my negative?

 

I remember when I tried to DIY telecine some Super 8 footage at home by removing my DSLR's lens and projecting straight onto the sensor, the image was great but I ended up with white streaks and flicker every 4-6 frames, and I guessed it was because the projector was old and I couldn't get an exact frame rate out of it (adjusting the frame rate knob would worsen or better the light streaks).

 

Or is it more likely a light leak somewhere? 

 

If it's a light leak could I solve this problem by enclosing the camera in a dark bag during filming (which could also act as a second sound blimp anyways)?

 

I'm going to run another camera test before I start principle fotography, but wanted some advice on what to try and change for the second test. Here is a link to the video of the test:

 

Any help/input is appreciated.

 

-Omar Lopex

ana-film.com


Edited by Omar Lopex, 20 July 2017 - 02:39 AM.

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#2 Jay Young

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Posted 20 July 2017 - 07:24 AM

It has to do with the sun angle against the shutter.  On that last shot, it looked like the sun was to the extreme left of the frame.  In this case most likely it will flare.  I have a bow-tie 16R, does the same thing.  You can actually shoot directly into the sun with no problems, but as soon as the sun hits the far frame edges, you get flaring/streaking. 


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#3 Omar Lopex

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Posted 20 July 2017 - 09:47 AM

Hi Jay,

Thanks for your reply. The only thing is that you can see the flicker through the entire test, even in the shots indoors.
In all the different lighting schemes, the flicker is the same, I think it's just more noticeable in the overexposed shot.

And the flicker is in the center of the frame, not the edges, like I'm led to believe the CP-16R with bow tie shutter causes.
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#4 Jay Young

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Posted 20 July 2017 - 10:36 AM

Hi Jay,

Thanks for your reply. The only thing is that you can see the flicker through the entire test, even in the shots indoors.
In all the different lighting schemes, the flicker is the same, I think it's just more noticeable in the overexposed shot.

And the flicker is in the center of the frame, not the edges, like I'm led to believe the CP-16R with bow tie shutter causes.

 

I only saw it on the last shot, but I'll watch again with a more discerning, coffee fueled eye.


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#5 Omar Lopex

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Posted 20 July 2017 - 11:02 AM

Yea the first time I watched it on my phone and couldn't really notice it, but on a computer screen it's visible. This is also an SD scan, so if I can see it here it would be even worse in a 2K scan (the format I would telecine the final product in)
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