Monday, July 11, 2011


Bolex 8mm cameras use a combination of  (1) drag from the pressure plate, (2) friction from the backwind roller, and (3) take up tension from an over-riding clutch than turns the lower spindle, to move film through the camera.

If all is in working order, film passes through the gate normally. Registration on the 8mm models is somewhat limited by the lateral movement of the film (weave) and the gate position (held by plate tension). H8 series Bolex camera eliminated this situation by using guide rollers, a better claw, and better method for moving the film.

I have worked on cameras that have had plastic electricians electrical tape applied to the pressure plate to increase the plate pressure. Although this in not a recommended procedure, the film did pass on without any apparent problem. I don't know if this actually improved the registration, though.

If you use this modification, be sure to check the operation of the camera for excessive plate pressure as the lower spindle take-up torque may tear film sprocket holes. The drag set in the lower spindle clutch is dependent upon the grease between its two friction plates.

Over time the grease will dry and the drag increase. If the plate exerts too much pressure with the attached tape, the film passing thought the gate may have the sprocket holes ripped or damaged. The increased pressure plate pressure in conjunction with dry (but not stuck)  clutch may also do the same.

                              Copyright 2011

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