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How it Works
Changing Shutter Speeds on a Kiev

Rev.2

Or, Why should a Kiev be advanced first before changing shutter speeds.

To clear up the confusion why one should advance their Kiev before changing shutter speed I offer the following tech tips. First a myth to dispel, you will not harm or break anything by changing shutter speed before advancing. You may however, cause a few things internally not to actuate properly.

 

 Here’s what happens when you merely change shutter speed without advancing with the image above. Stepped Lever (A) is pushed in direction of Blue Arrow causing Escapement Actuator (B) to raise off of the step notch of Lever (A). When you release the shutter speed knob after changing to a new speed Escapement Actuator (B) just falls back into the same step notch of Lever (A). Notice the spring attached to Escapement Actuator (B), this will always pull (B) to the last step notch on Lever (A) as shown. The notched steps in Lever (A) are important as they set up the position of Lever (A) which influences the switching in of particular escapements.

 Above is the proper sequence of events when you advance first before changing shutter speeds. The example shown will change from 1/125 to 1/50 speed. This image is currently advanced and set at 1/25 with Stepped Lever (A) is at resting state, Blue Arrow showing the direction that the lever has moved to and Escapement Actuator (B) is engaged in the bottom notch of the Lever (A).

Notice Cam Follower (C) on Escapement Actuator (B) and Cam Disc (D), the action of these parts will be important in the following sequences.

 Next step in the sequence is to change shutter speed to 1/50 whereby Stepped Lever (A) is moved in direction indicated by Blue Arrow when you lift the shutter speed knob. This disengages Escapement Actuator (B) from the bottom notch on Lever (A). When you turn the shutter speed knob, Cam Disc (D) is rotated and Cam Follower (C) rides up on a cam lobe causing Escapement Actuator (B) to pull over to the next step notch on Lever (A).

 The last step in changing shutter speed to 1/50 is to release the shutter speed knob allowing the knob to drop down into place. With this action Stepped Lever (A) is released in direction indicated by Blue Arrow. Cam Follower (C) is still riding on top of a cam lobe on Cam Disc (D), which maintains the position of Escapement Actuator (B) to engage the desired notch on Lever (A), in this example for 1/50, the first notch up from the bottom. This completes the sequence of events to change shutter speed. Further changes to say, 1/10 speed will initiate a similar series of events.

 The summary of above is; without advancing before changing shutter speed, Cam Disc (D) would not rotate thus not setting the position of Escapement Actuator (B) on Lever (A). One could argue however that even if the shutter speed is changed first and then the shutter is advanced, that Cam Disc (D) should push the Cam Follower (C) out and Escapement Actuator (B) would snap into the proper notch on Lever (A). True, in a perfect world, where the tolerances of our finely crafted shutter mechanism are set such, that Escapement Actuator (B) will catch the desired notch on Lever (A) every time. In reality, if Escapement Actuator (B) misses or does not catch the lip on the notch intended on Lever (A) then the spring will pull (B) down to the next notch step on Lever (A) giving a faulty speed selection.

 Here’s where we place an exception to the rule on the above treatise. You can change shutter speed before advancing on the shutter speeds in the range 1/125 to 1/1250 as there are no cam lobes to engage or changes in the position of Escapement Actuator (B) at all in this range.

June 24, 2007