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Arthur Sanchez

Shutter out-of-phase? BOLEX REX series - How can you determine if the shutter is in phase perfectly

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Other than the obvious Out-of-phase problems. is there a way to determine that your shutter is perfectly in phase?

 

I shot some camera tests and and some scenes revealed a phase issue and some were ok.... weird!

 

why would this be?

 

Arthur!

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The service manuals describe how to set the timing, they're pretty essential for anyone wanting to be a serious repairer.

 

You need to have both the shutter timing and pull down timing correctly set.

 

To check the shutter timing, when set to extended single frame the shutter should pause in the open position with the edge of the shutter just visible through the lens port above the gate opening.

 

The pull down timing should be set so that the film is advanced just after the shutter closes. With the motor disengaged you can manually advance the movement and observe when the claw tip begins to move forward relative to the shutter. To double check, mark some film with a sharpie and observe through the lens port as you manually advance the film, there should be no movement of the film visible before or after the shutter closes.

 

From memory the claw pivot position on its gear should be something like one or two teeth clockwise past the meshing point when stopped.

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Dom Jaeger, I don't expecting you to give a full lesson on timing the film pull down claw and shutter, but do they get out of synchronization once set?

Wouldn't this indicate some damage or mishandling of a film jam? Possible signs of a larger problem that needs to be addressed first?

Edited by JD Hartman

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so which do you adjust? the gears on the claw? or the shutter blade itself... adjusting the gear is making big incremental jumps... not fine tuning.

and I only find this phase problem with variable shutters on the REX.

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Dom Jaeger, I don't expecting you to give a full lesson on timing the film pull down claw and shutter, but do they get out of synchronization once set?

Wouldn't this indicate some damage or mishandling of a film jam? Possible signs of a larger problem that needs to be addressed first?

 

Well if everything is correctly set and secured, no the timing shouldn't slip. The pulldown and shutter timing are both controlled by gear meshings that can't really jump teeth, but if the grub screws holding the shutter gear are loose, or the locating square of the pulldown gear is worn or the holding screw loose etc, then the timing can slip. But usually the timing is out because someone has removed the front (which loses the shutter timing on a REX) and then put it back without checking the timing.

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so which do you adjust? the gears on the claw? or the shutter blade itself... adjusting the gear is making big incremental jumps... not fine tuning.

 

and I only find this phase problem with variable shutters on the REX.

 

I would set the shutter so it stops just above the gate aperture when you press the single frame set to "T", then adjust the claw gear if you need to. But unless you've removed the claw gear it should be correctly timed. Check that the shutter gear (held with 3 grub screws) isn't slipping.

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Dom... I finally have the shutter aligned perfectly... it took adjusting both. But what's most interesting to me is how almost all REX series cameras with variable shutter are a tiny bit out-of-phase.

 

Shocking!

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