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Blurriness only on one side of the frame Bolex S16 Rex 4

Anna Warner

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Hey guys! Hoping someone can help me. Here's a link to the footage issue I'm having: https://vimeo.com/865774980/1bf702c391?share=copy

I compiled the worst examples from three rolls of film. I have NOT shot footage through this camera before, so this is my first experience with it, and I bought it from someone who had already had it converted to S16 via Dr. Bolex. As you can see, there's a bizarre blurriness happening on the right side of the frame that extends through the center and 'wobbles' in and out at times. Has anyone seen anything like this before and can help me troubleshoot? 

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Looks like the lens mount is not properly aligned. The flange focal distance must be set at a very precise distance so what you see on the focusing screen or the viewfinder is what you capture on the film. Looks like the mount or the gate is at an angle. It could be caused by a warped turret. It could also be a bad job when they did the conversion. A technician will have to evaluate the camera. I wouln't send the camera to the same technician.

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I would first check that the images on the film itself are soft on one side, to rule out a possible issue with the transfer.

If it is indeed on the film, then it looks like the film was not seating flat in the gate. Check that the pressure plate latches closed properly. I don’t think it’s an issue with the lens mount or turret - it would need to be quite noticeably warped to produce this much flange depth variation from one side of the gate to the other.

A Super 16 gate actually needs either an enlarged pressure plate to properly span from one support rail to the other, or the pressure plate needs to be shimmed to sit a little further to the left. I’m not sure how Arthur (Dr Bolex) solves that issue with his conversions, but if it’s just the original pressure plate unmodified it could cause some issues with film flatness.


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I second Dom's assessment of the pressure plate. I cannot now remember if the Bolex gate has rails of a flat surface. If there are rails and the extended image side rail has been milled narrower, then the pressure plate is likely to be pressing inwards of the rail edge and bulging the film towards the lens.

Another cause may be the edge guides of the gate which hold the film steady from weaving. I cannot recall if they are adjustable. If so, then they may have been set too close to each other and causing the film to cup out of focus and also lift the pressure plate. The momentary increases in the defect suggest that film shape memory from being parked around a sprocket may be lifting the pressure plate slightly higher passing through. 

From memory, the pressure plate on my RX5 was black plastic and there was considerable clearance between the side rails and the pressure plate edges. The variations may be the film tension through the gate buckling the film a little more until the motion stabilises.

I had a bulge problem with a CP16 caused by an edge guide which had become skewed during reassembly after some maintenance. It was never apparent until the first time a shot indoors in low light with fully wide aperture and there it was as plain as day. Lost a critical 100ft roll to it.

The light leak may be from two causes :

Damage to a little plastic bloop-lamp housing on the bottom right of the camera as viewed from the front.

Light passing around the very edge of the shutter disk which may not be of quite wide enough diameter. If the light is rebounding from newly dressed metal in the gate aperture, painting that edge with lens black or a sharpie may be a temporary fix. 

A fix is realistically the province of a camera tech to sort out. 

Edited by Robert Hart
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Further to my comments above, the light leak looks like normal edge flaring from light passing into the gap of a daylight spool because after a while it goes away. If you inspect the film by eyeballing the film itself, you may observe similar leak flares on the sprocket side of the film. 

Another cause of variation of focus may be the three lens turret if you camera has one not being locked down. From memory, there should be a little dummy plug which screws into the body through the upper lens hole. If that is not fitted or loose, a heavy lens may droop downwards slightly and cause varying focus between the upper edge and lower edge. 

Gently lift the front of the lens and check that the turret disk is not moving, closing and opening a thin gap at the top between the turret disk and the front of the camera body. If looking through the viewfinder when doing this, you may observe focal shifts.

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