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    Mike Wilde's Avatar
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    Aug 2006
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    Polaroid J66 to 70mm filim modification

    I was gifted a Polaroid J66 in excellent shape, in a leather case that looks like it never left the closet. It looks as new as if this was 1962 and it too was new, complete with the original manual. It came with an empty type 47 film box, so it apparently has seen at least one film.

    There ended up being about a million of these things sold, at $90, which was some money in the day. The guy who gave it to me bought it at a nursing home garage sale in 1982 because it looked neat, but has never used it.

    This was Polaroids first auto camera, and proclaimed to use 3000 asa b&w film. This film's production ceased in 1992 or so.

    The shutter and selenium cell that sets it speed seem to be working properly, as does the aperture control. Web research turned up the tested speed range of the shutter, and the aperture of the lens. The speeds appear to range between 1/10 and 1/400

    Using the direct flash recommended aperture settings from the OEM manual, and data on the guide number of AG-1 flash bulbs, I was able to confirm that the 114mm lens is about f/19 at it's 'normal' aperture, perhaps f/ 13 at its lighten setting, and around f/26 at it's darken setting.

    Using Parker's 'The ultimate exposure guide' I was able to work out the EV's that this camera appears to respond to. It looks like it should work just fine in the outdoors without flash using about 200 speed film.

    I have a 100' roll of 70mm Portra 160NC film in the freezer mostly still full left over from another mad experiment that would be a good candidate. It will yield a 70mm x100mm sized negative, and so I think I can make about 15 rolls of 5' of film for this camera under modification, that could yield about 200 images before this film is all gone. After that perhaps an ultra panoramic 35mm modification may be a possibility.

    I worked out that I could load the camera with up to a 5' roll of this 70mm film at one time, and still be able to process it on a paterson plastic roll.

    A single tank Paterson central tube was shimmed with SAP tape to hold the larger central diameter half of the split tanks spiral roll onto the tube while it was not engaged with the smaller central diameter half, which normally snuggly grasps the central tube. The smaller central portion half of the spriral rides up againtst the other half, and while doing so, perfectly accomodates a 70mm film width.

    To fit the 70mm film into the camera I put the supply roll in the chamber where the receiver paper roll once sat. The edge of the bakelite form was lightly filed to create a gate to guide the 70mm fim across the pressure plate and head towards the take up side, which is where the negative roll originally sat. There will be no backing paper so far, so this will be a load and unload in darkroom type of camera.

    At the negative spool side a 70mm spool was fashioned from sawing the plastic central spool of a 35mm cassette in half, and carving some 3/8 dowel to form a 35mm extender to yield a 70mm long spool. At the bottom end of the 35mm portion a short stub of dowel was formed to hold the assembly in the original negative spool support.

    At the top end of the spool, the center portion of the existig spool support was drilled though with a 1/4"drill bit to the top of the camera to allow a film winding mechanism to get to the outside of the camera.

    A carriage bolt was passed though this hole from the outside, and fitted to allow the correct alignment of the take up spool to the supply roll by shimming it with washers and double nuts. The bolt end was carefully notched using with a hack saw and small files to cut a slot that engages a cross tab in the middle of the inside of the top of the 35mm spool.

    The carriage bolt underside lightly engages with plastic camera top that sits over the cast aluminum body. This provides the required friction to aid in the bolt not rotating on its own.

    One side of the square portion of the bolt underside has been sharpie marker painted red to aid in counting the turns to advance the film. Testing was carried out with the film back openned. Using scraps of spoiled 120 film that I keep around to teach loading of rolls, I was able to determine the needed winds. The first 6 frames need 3 turns of the bolt between exposures, and the last 8 only need 2.5 turns since the diameter of the take up roll has increased by the film wound on it.

    I will try to post images once I get a film though this beast and have it processed.
    Last edited by Mike Wilde; 06-15-2010 at 03:03 PM. Click to view previous post history.
    my real name, imagine that.



 

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