A Mounting Jig for use with 35mm Stereo Cardboard Mounts

Basic Design Aim:

1. General Description

The mounting jig is designed to enable quick and accurate mounting of stereo slides into cardboard stereo mounts. It is best used in conjunction with a light box to illuminate the slide, and a pair of stereo viewing lenses to view the slide while mounting.

2. Quick Starter to Using the Jig

If you have had previous experience with stereo mounting, you may like to go right ahead and use the jig, or it may be useful to read this summary. A diagram of the jig is attached.

Calibration

• If using the jig for the first time, it is best to calibrate it to your camera. Once calibrated, no further adjustment is required (unless mounting film from another stereo camera). To calibrate the jig, loosen one pair of locking screws, and turn the associated pair of adjusting screws until the reference edge is at the correct height for your camera. Then tighten the locking screws to fix the reference edge in position. Either, or both reference edges may be adjusted. It may take a few frames before you finalise the calibration of the jig. Adjustments small as 1/8'th of a turn can make all the difference, so be patient.

Use

• Place the jig on a light box with the locating cover open. Place the stereo mount into the jig with: the inside surface of the mount facing you; the rounded apertures towards the reference edge; and the edge of the mount tucked under the reference edge lip. The jig may be used in either orientation, depending on whether the finished stereo mount is required to have the tape across the top (use as shown in the diagram), or across the bottom (use up side down to diagram).
• Place the film chips on top of the round cornered apertures - the left image is placed back-to-front over the right side aperture, and the right image is placed back-to-front over the left side aperture.
• Fold down the locating perspex cover to partly hold the film chips in place.
• Push each film chip up against the reference edge to locate each chip vertically - and also make sure the stereo mount is also pushed up against it's locating edge.
• Set the stereo window by sliding the chips horizontally until satisfied. At this stage it is handy to be able to place a pair of stereo viewing lenses over the jig to see the magnified image as it is in the hand viewer. (Space does not permit a full discussion of how to set the stereo window. If necessary, consult a fellow stereo worker, or see Ferwerda's "World of 3D".)
• If for any reason the baseline alignment is not correct, or within acceptable limits, re-calibrate the jig.
• Tape the film chips into position with Scotch #850 tape along the film edge protruding from under the locating cover. To ensure that the film chips don't move, push down firmly on the hinged cover while placing the adhesive tape into position.
• Remove the mount, check the image in the stereo viewer, and tape the mount shut across the top. A special slot at the back of the jig is provided to hold the mount upright while taping the mount shut.

Notes

1. The jig will reveal any variations or deficiencies in other factors that affect the vertical alignment (or baseline alignment) of the stereo image. Such factors are:

• If the stereo mounts used are not accurately made, any variation in the vertical position of apertures will result in the baseline alignment appearing incorrect. Use of the precision cardboard stereo mounts will ensure satisfactory performance in this regard.
• Variation in the film path through the camera could introduce some variability in baseline alignment.

   

2. If for any reason you have dismantled the jig and are going to re-assemble it, or need to reset the calibration of the jig back to the nominal "factory" settings then note that there are several alignment markings cut into the baseplate of the unit. These lines are just a few millimetres long, and can be best seen by examining the baseplate from underneath. The following alignment markers can be seen, working from top to bottom as oriented in the diagram:

• One pair towards the top of the jig for aligning the leading edge of the 10mm thick bar across the top of the jig.
• One pair for aligning the white "locating edge" plastic.
• Two pairs of markers, one for each reference edge. These are 3mm away from the position of the white locating edge.
• Two other pairs of markers near the edge of the base plate - these just mark the position of the rebate in the baseplate and were used during manufacturing.

3. If the mounts being used are too thick, then the depth of the rebate in the baseplate could be increased to cater for thick mounts. The jig should cater for thicknesses in the range 0.5mm to 0.8mm.