2.When an ambeint light exposure is being made, all of the action just described takes place but does not affect the shutter action. However, when a flash array is inserted switch S2 in the flash socket programs the electronics to energize solenoid #2. The impact of this action on the movement of the shutter blades is described in paragraph F.4. but first the shutter blade actuation must be described as follow :
3.When the ECM circuit powers solenoid #1, the solenoid plunger is pulled into its seat, overcomming the opening spring force. The plunger pulls the walking beam, rotating it about
60degrees.
Each of the shutter blades has a pin which engages a slot in the walking beam. As the walking beam rotates, it transmits its rotary motion to the shutter pins and drives the rear blade to the right (facing the front of the shutter) and the front blade to the left thus closing the light path of the picture taking lens and the light path of the photocell lens. When the shutter is totally closed and the gear train has reached the point in the sequence at which the Fresnel carrier snaps up, the exposure sequence starts. The blades will proceed toward the fully open position and retrun to a closed position in the time interval dictated by the photocell and integrating circuit. The blades may not reach the fully open condition if the illumination level is high, or they may fully open for a period of time if the light level is low. If a flash array is mounted, the blades may not be permittedto open completely because of the follow focus mechanism described in part in the foregoing paragraph. The following paragraph explains the interaction of the follow focus components and the shutter blades.
4.Installing a flash bar in the camera flash socket switches the ECM to the flash mode.As previously explained, at a point in picture taking sequence (flash mode), solenoid #2 is energized. Fastened to the plunger is pull down bar. when the plunger pulls this bar down, it moves the interceptor into the position where it will intercept a pin (the stop pin) on the walking beam (Figure
Figure 2-9 A Solenoid S2 operation
5.The shape of the pin on the walking beam si such that once contacted by the cam interceptor it remains latched in that position until solenoid #1 actuated during the next phase of the shutter cycle. When the plunger on solenoid #1 pulls in, the follow focus pin disengages from the interceptor and the solenoid #2 plunger returns to it original position under the force of the interceptor hinge spring.
6.Since the photocell components are contained within the shutter housing, they are included in this discussion. A lens is employed to focus the reflected light from the subject on the photocell. A second pair of openings in the shutter blades control the amount of light received by the cell as previously described. A variable neutrality density wedge system is employed to provide lighten / darken adjustements. (Trim assembly). The operation of this control differs slightly from those used on other Polaroid cameras. When the camera is folded, a cam on the shield of the front cover strikes a release lever on the lighten / darken assembly and returns the trim adjusting wheel to its center (normal) position. The trim wheel is automatically centered when the camera is closed.
7.To compensate for any variations in individual photocell characteristics, a neutral density filter is selected and installed in front of the photocell lens during assembly. A calibration must be performed and a filter of correct density installed any time the ECM requires replacement.