Polaroid Film Conversions

Converting a Polaroid pack film camera to use an Instax wide back

This will require one Instax wide camera and one Polaroid pack film camera. The Polaroid camera should have the extra exposure settings which allows it to be set for 300 ASA, so that metering with Instax film is possible. It may be possible to use any camera by setting it to 3000 ASA and using a 2 (or 3) stop ND filter over the electric eye. I found that exposing with the 300 ASA setting is pretty close since these cameras are getting old and often need exposure compensation of 1 mark toward lighten anyway because of the aging electric eye. An overview of the conversion is described in this video. An overview of preparing an Instax 100 to be used as a back is shown in this video.

Preparing the Instax camera

This operation involves taking the Instax camera apart and removing the electronic guts, leaving just the motor, gears, and rollers. If using an Instax 100, the lens body needs to be cut off with a hacksaw blade or other tool. The lens body on a 210 is not attached to the back, so won't need to be cut off. The trickiest part is lengthening the depression on the cycle cam (Instax 100) or the slot on the cycle gear (Instax 210). This prevents the motor from running on and activating the cycle switch again, thereby ejecting all of the pictures in the pack. The length needs to be doubled. Use a file on the cam (Instax 100), or a drill/dremel on the gear (Instax 210). Lengthening the cam is fairly simple: just file/cut away the cam, lengthening the depression. The 210 is more involved as it requires taking apart the gear box:

Lengthening the slot in the cycle gear on an Instax 210:

Remove the battery pack and gears underneath. Remove the spring from the film pick. Hold the back upright so the gears don't fall out.
Remove the microswitch.
Unclip the bottom two retainers and release the upper gear housing.
Take off the 3 gears driving the cycle gear and remove the screw holding the upper gear housing. Remove the housing.
Remove the cycle gear. You'll notice a slot in the gear. This is what you will need to lengthen.
Using a drill or dremel, double the length of the slot, being sure not to drill/cut too deep or long. It doesn't have to be perfect. It just has to allow the microswitch to stay off for a longer period of time.
Just to give you an idea of what you're doing, the microswith falls into the slot and turns off when the gear turns to the correct place in the ejection cycle to turn off. Normally, electronics control the motor and turn it off quickly. You can accomplish the same thing with a relay which shorts out the motor when it's turned off, but I think it may be more simple to just lengthen the slot to give the motor time to slow down and stop.
Reassemble the gear box in the reverse order of disassembly.
Cut a notch on the left side (from the front of what's left of the camera) to make room for the scissors guide on the pack camera. Also, trim the ridge just below the rollers.

Wiring the Instax back:

The idea here is to make a simple circuit which connects the motor to the battery with the cycle switch in series to keep it only ejecting one picture at a time. An eject switch is wired in parallel to the cycle switch to kick start the motor long enough for the cycle switch to take over and complete the ejection sequence. This video shows how this is done. Skip forward to the wiring part. Here's an explanation: the negative battery wire is soldered to the top terminal of the motor. The other wire from the motor is soldered to one of the terminals of the micro switch. Keep the existing wires attached to the micro switch. The positive battery terminal is soldered to the other micro switch terminal. This will cause the motor to advance the film out of the rollers until the micro switch turns off by the depression in the cam or gear. The wires from the shutter button are wired in parallel to the micro switch.

The carbon dot under the rubber shutter on an Instax 100 is replaced with a piece of aluminum foil for a better contact. The Instax 210 has a microswitch for a shutter button and needs no modification.
Solder a wire onto the appropriate battery terminal depending on the voltage requirement of the camera. Check the comparison chart to see what voltage your camera needs. Run this and the negative wire outside the camera.
Attach the back of the Instax case to the back and run the battery leads to the front. Place a piece of craft foam over the rollers protruding down so it clamps against the camera when mounted to prevent light leaks.

Preparing the Polaroid camera

The back of the camera is removed by drilling out the 4 rivets holding it on. The battery chamber is removed and the wires trimmed (they will be connected to the Instax battery later). Remove the front of the battery compartment. Remove the bellows from the body of the camera. You can remove it from the lens body, but be sure to cover it while cutting the camera body.
Although you can move the lens body back by preventing the scissors from opening fully, I would recommend moving the lens body back with spacers. This is the best method, though it won't allow you to close the camera down into its case, since the viewfinder won't completely fold down. But it allows the use of the portrait and closeup attachments without being concerned whether the rangefinder is accurate or not. This can be done two ways. One method is mount the Instax back 18mm behind the original film plane and move the lens body behind the vertical strut. See these instructions on how to do that.
Or, you can mount the lens body back a lesser amount and to the side, which helps compensate for the back being over to the left of the camera. As in the itype film conversion, cut 2 tabs and drill them with 2 3/16" holes the correct distance apart (around 12mm), a little more than the distance from the film plane to the instax film plane. This is tricky, because if the distance is too short, the vertical strut will be in the way of the shutter release.
Cut another tab for a spacer on the left side of the horizontal strut and screw it into place. Make sure the lens body is mounted straight onto the horizontal strut.
Cut off the left side of the camera leaving just the top curve. The ridges on left and bottom sides are cut off so the Instax back can be mounted as close to the film plane as possible. And the bottom plate is cut to the tripod socket to facilitate mounting the back. I used a hack saw blade to do the most of the cutting, and a file to finish. I found a hack saw cuts much faster than a dremel and doesn't get the body as hot.
Cut a notch in the lower left hand side of the camera to make room for a random gear on the Instax back. Line up the back to the camera to see what needs clearance and how much needs to be cut away.
Trim the lower left scissor guide to make room for the Instax back. Be careful not to cut too close to the guide slot.
Cut craft closed cell black foam to to fit inside the Polaroid film area and cut a hole the size of the Instax film. The foam I had is about 2mm thick, so I cut three sheets to stack between the Polaroid and the Instax back. The last sheet is cut bigger, making it protrude out of the bottom of the camera to provide a light seal between the rollers and the outside world. I found I had to mount the back at the bottom left edge of the film plane. Since Instax film is the same width, but 1/2" shorter than Polaroid film, this means the picture will be what appears in the top right of the viewfinder. The image will be cropped a little on the left, and about 15% on the bottom.
Lay the instax back onto the back of the camera to check the fit. You may need to add a layer of foam or do finishing touches on mating surfaces.
Flip the camera over and check to make sure the instax back is lined up similar to as shown. It should be near the bottom, over to the right a bit.
Cut a wide tab from a tin can and predrill 2 holes into the side of the camera, mounting it with 2 screws.
Mount the instax back onto the camera, being sure the wires from the battery compartment are not pinched and are led to the outside of the camera. Press down onto the Instax back while predrilling holes into the instax back and inserting the screws. Press down hard enough for a good light seal, but not too hard so the back is pressed to far towards the film plane.
Cut another smaller tab to attach the upper left hand side of the camera to the back. Predrill all holes, mounting the tab to the camera before mounting it to the back while pressing down on the back.
Cut a longer tab and wrap it around the scissor guide at the bottom of the camera and screw it on. While pressing down on the camera, wrap the tab around the instax back and screw it to the back.
Attach the leads from the Instax battery to the leads going to the lens body. Use shrink wrap and don't make the leads too long, as they need to be tucked into the side.
Trim the back door to the correct shape to fit around the back. Try to keep the latching tabs on the back with the tab door intact (it may have to be glued once you cut one of the rivets). This will allow you to latch it onto the back using the door latch. This step takes a lot of time trimming it just right and making the locking tabs engage with the latch mechanism on the camera.
Mount the door trim onto the back. You may need a small piece of tape on the upper left arm of the trim to keep it in place.
Remove the focus knob on the left side of the camera, trim it, and remount it upside down. Fill in the gap below it with a piece of trimmed battery compartment.
Here are all the pieces left over from this build. Save these pieces in case yor do more camera hacking and you need various bits and parts to fill things in.
The case will need to be trimmed for it to close over the lens body. This is the same procedure as trimming the case for the itype film conversion

Counting the exposures can be done with a piece of paper with 10 tabs cut into it, taped onto the back or inside the case. One tab is ripped off when a photo is ejected.

There you have it! A Pola Instax camera in 33 easy steps! Contact me if you'd have questions or would like to share your build.