S-16 Re-Centered Mirror Support Spindle and Plastic Connecting Rod

The HD-144 Mirror Offset Spindle and Connecting Rod is only included in the GOLD Kit.

Re-centering the mirror achieves 100% symmetrical timing between the shutter and the mirror. This is accomplished by means of an “offset” spindle, and shorter connecting rod.

HD-144 Spindle/Rod (Left)
Regular 16 Spindle/Rod (Right)

Two minor modifications need to be made in the camera: a corner of the Base Plate (MIN 5) must be filed down slightly to allow the re-centered mirror room to spin without touching the Base Plate (see photo below), and the side of the Drive Shaft Sleeve (MIN 30) needs to have a small recess filed in order to avoid coming into contact with the base of the mirror shaft (see photo below). These two operations will need to be done in small steps until the amount is just enough.

Circled in RED above are the two areas requiring slight modification. The Recess added to the Drive Shaft Sleeve appears as a ‘dimple’ above an empty screw hole right above the rod’s center. (There is room for the screw; it has been omitted to make the recess visible in this photo) A corner of the Base Plate to the right of the Mirror Shaft has been filed down  (it has been left unpainted here to illustrate. An ‘X’ is scratched in to the right.)

As the re-centered Mirror moves to its furthest left, the base of the Mirror Assembly will now not touch the Drive Sleeve Shaft, and the Mirror Shaft won’t touch the area of the Base Plate to its right.

The HD-144 Mirror Support Spindle is screwed in to the ACL Base Plate with the Spindle just off-center to the right. The HD-144 Spindle is provided with its own screw at the top …. the Eclair screw uses a different, non-standard thread and will not fit the new Shaft. Once the Mirror Shaft is secured by placing the screw in the top of the Spindle, it is critical that there is absolutely no play up or down of the Mirror Shaft what-so-ever, yet with the mirror still able to turn freely. If there is any play at all up or down, the image through the viewfinder will be jittery. If the Mirror Shaft is held down too tight, it could damage the camera’s gears. This is a very critical adjustment — its importance cannot be overstated.

Eclair manufactured the factory Spindle Washers (MIN 81) in various amounts of thickness ranging from about .85mm to 1.15mm, and would select the most appropriate washers for each individual ACL as it was assembled in the factory. Since there is always a possible fraction-of-a-millimeter margin of difference in height between the Regular-16 and Super-16 spindles, it may be necessary replace an existing washer with a new one that is either a fraction-of-a-millmeter thicker or thinner than the original. IT IS NECESSARY FOR THE CAMERA TECH TO HAVE A VARIETY OF THESE WASHERS ON HAND OF VARIOUS THICKNESS (or suitable shim washers).  Also bear in mind that the thickness of the lower WASHER in the MIRROR SPINDLE will affect the mirror’s exact path.

There is virtually no breathing room for the MIRROR; if too far back it will scrape against the shutter and/or the spring that guides the claw. Too far forward and it will hit the the camera body and/or the rear rim of the Flange (this will sound like a machine-gun, and probably damage the Mirror).

NOTE: Tests have shown that ACLs converted to Super-16 with a 144-degree shutter, but without re-centering the Mirror do seem to shoot quality images, even though the timing of Mirror and Shutter is less than 100% symmetrical on both sides of the aperture opening. Technically the Super-16 edge of every second frame is being under-exposed by a micro-second. Most Techs will advise that this is too small an amount to matter. Some owners will install this offset anyway, for “peace of mind”. Many owners do skip this step, and may be perfectly happy with the results. However performing this re-centering will keep the camera up to 100% original Eclair  ACL Specs, which is what the HD-144 GOLD conversion is all about. This part of the conversion will also ensure that the mirror is in the proper position when “parked” by a self-parking motor (ACL II).

NOTE: European ACL owners may consider re-centering the mirror to be more critical that their American counterparts, if the choice is made not to use a 144 degree shutter because of European power cycle considerations with HMIs — re-centering the mirror would minimize any extra theoretical underexposure on the right side of the frame caused by an un-centered mirror, even if miniscule. Consult with your Tech.

It will be noticed that the body has two square holes to allow room for the corners of the mirror to clear. However because the mirror is being shifted by approximately 1.1mm to be re-centered, it now takes a new path and it will likely be necessary to enlarge one or both of these two square holes and possibly file part of the rear rim of the Flange. The square holes on the French ACL body are slightly smaller than those on the English model, which means that Nationality of ACL body will have an effect on how much filing may need to be done.

As you look at the camera body from the inside, it is the left square hole and adjacent Flange rim that most probably will need to be filed. If this is not done correctly, the mirror could hit the nearby area and crack . BE CAREFUL!

It is recommended that at first the Flange be pulled off, and the Mirror be moved slowly with the motor inching knob, so that the Mirror’s path can be seen from the Front of the body. If the mirror comes too close to the rear rim of the Flange or to the edge of the small square holes in the body — file! This point in the procedure is a place where damage can occur if not done with 100% expertise.

If the mirror makes any noise when the camera is running, a suggestion for determining just where the mirror may be contacting the body is to place a very thin coating of white cream (such as facial cream) around the edges of the mirror. Run the camera for a second, and then examine the inner camera body to see where the cream has been deposited.

Many mirror arms many be microscopically unevenly worn at the bottom from years of use, or the offset spindle may be microscopically smaller in diameter than the hole in the arm. This may prevent the mirror from being totally stable — resulting in image jitter through the viewfinder (but not on film); To test: can the mirror be tipped up and down with a finger even a microscopic amount after the optimum thickness of washer is in place? If so, and if jitter through the finder occurs, a razor-thin shim super-glued to one side of the base of the arm to tip the arm microscopically may solve this problem. (Cutting a .1mm thin copper shim washer in half might work as the shim). With this shim in place, a new thickness of Top Washer may be required to compensate.

Finally, the plastic Connecting Rod is snapped into place. IMPORTANT: The inner diameter of the openings in the rod have been made on the conservative side. It might be necessary to reduce the tension of the rod by slightly enlarging the inner diameter on either end. If necessary, use a small, ball-head Dremel(R) tool to slightly enlarge the inside of the hole in tiny increments until the rod just turns freely when the ball is snapped in place. Don’t over-enlarge! DON’T ENLARGE THE SURFACE DIAMETER OF THE OPENING UNLESS ABSOLUTELY NECESSARY — THIS TIGHT DIAMETER IS WHAT KEEPS THE BALL SECURED IN THE ROD. Setting the correct tension of the Connecting Rod is necessary to prevent damage to the motor and/or mechanism, and to prevent the possibility of image jitter through the viewfinder.

It should be reiterated that the original ACL 24/25 fps motor should not be used to drive 400 foot magazines — this could burn-out the motor.

A Super-16 Hardened-Steel Connecting Rod is also available as an accessory — see the “individual parts” page at: www.members.aol.com/Super16ACL. This Super-16 version is based on the original design that Eclair eventually discontinued in favor of the plastic rod.

Though a more expensive part than the plastic rod, the Hardened-Steel rod may last the life of the camera … although there’s no warranty made on that. When tightening the screws on the caps, just gently pinch the entire assembly without applying too great a pressure. Use thread lock when installing the Hardened-Steel Rod to minimize the possibility of the caps becoming loosened through use. Because the Super-16 Hardened-Steel Rods have not yet been tested for tens of thousands of feet of film, there is the unknown possibility that after a certain amount of film has been driven through the camera, the caps could need to be re-tightened. No Warranty is made.