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Buying film for Bolex, and other questions


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#1 Jon O'Brien

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Posted 10 October 2017 - 05:25 PM

Hi, I'm about to order a roll of 16mm. Is there anything that I need to specify to the supplier about roll or perf type? It's for a S-16 Bolex reflex and the only thing I know is that it's going to be 100' Kodak Vision 3 50D.

 

A video on youtube says that for a reflex Bolex you need to open the diaphragm about 1/3 of a stop over what the light meter says, due to the viewfinder prism diverting light away from the film. Is this correct? It makes sense:

 

 

Another question if anyone knows the answer: is a Bogen 3066 fluid head designed to have the horizontal pan travel locked down? I've located a tripod and head but the seller says he's not sure if the travel can be locked. Thanks for any help.

 

 


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#2 Jean-Louis Seguin

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Posted 10 October 2017 - 06:16 PM

The film must be 1R or single perf.
Yes the 3066 has a pan lock.
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#3 Dom Jaeger

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Posted 10 October 2017 - 07:02 PM

You do need to overexpose by about 1/3 stop to compensate for the prism diverting light to the viewfinder.

 

The manual has exposure times listed, as well as 'adjusted' exposure times that compensate for the light loss. So for a reflex Bolex with a 133 degree shutter, at 24fps your exposure time is 1/65 sec, but the adjusted exposure time that compensates for the prism is 1/80 sec.

 

Some people prefer to alter the ASA setting on their meter instead, some set it to 24 fps cine mode (which assumes a 180 degree shutter so 1/48 sec) and open 2/3 stop to approximate 1/80 sec, whatever you find easiest. 

 

There is occasional misinformation out there that states that RX lenses have their f stop marks adjusted to compensate for the prism light loss but this is not true, they are marked like any other lens.


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#4 Simon Wyss

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Posted 11 October 2017 - 12:42 AM

bump, please delete


Edited by Simon Wyss, 11 October 2017 - 12:44 AM.

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