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Tobin Time Lapse Motor


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#1 Katy Dove

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Posted 25 August 2010 - 06:03 PM

I'm new to 16mm and trying to get my head round the Tobin Time Lapse Motor. I'm using a Bolex H16 Reflex (RX5).
My questions are concerned with correcting exposure/ FPS/ exposure time.
The TTL runs at .75 FPS, exposure time 1/2 sec.

I'm trying to shoot some footage of light and shadows moving through trees over the course of the day.

Firstly I'm concerned that the 1/2 sec exposure time will lead to blurred images if the trees are swaying slightly. Would this be the case and is there any way round this?

Secondly, is there an easy way of calculating how to set the exposure correctly? I have read the manual but find it confusing. I'm using 250D film. I have a .6ND filter.
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#2 Glenn Brady

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Posted 29 August 2010 - 07:26 AM

Firstly I'm concerned that the 1/2 sec exposure time will lead to blurred images if the trees are swaying slightly. Would this be the case and is there any way round this?


You could use the variable shutter to reduce exposure time, setting it at the 1/4 closed or 1/2 closed position (the lever markings '1/2' and '1' respectively). The 1/4 closed position would give an exposure of approximately .36 second and the 1/2 closed position approximately .21 second. Of course, you would have to take into account the light loss of the camera's viewfinder prism.

Secondly, is there an easy way of calculating how to set the exposure correctly?


Adapted exposure times on Bolex RX cameras at all speeds are roughly .82 of real exposure times. If you multiply the advertised film sensitivity of the stock you're using by .82 and set your lightmeter to the resulting number, you'll be metering accurately.
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#3 Oliver Christoph Kochs

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Posted 29 August 2010 - 07:57 AM

Katy, you said:

"Firstly I'm concerned that the 1/2 sec exposure time will lead to blurred images if the trees are swaying slightly."

From my experience just the opposite is the case. When i shoot timelapse i always use ND filters to get really long exposure times. Reason? I want the parts that move to be blurry because it creates smoother motion. Imagine a swarm of birds flying by or insects in front of your lens. This will ruin your timelapse but long exposure time makes these issues invisible. I would go as far that the longest possible exposure time suits me best but of course the number of ND filters is limited - use a maximum of 2x 0.9 NDs which is a 6 stop reduction. Use glass filters not plastic.
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