The lever will allow you to slide the telescope or dovetail bar simply by moving it, instead of turning the knob. Put a dovetail on there by turning the knob but not all the way tight. Do this with the lever positioned on the left, as in your picture. Then move the lever to the right to lock in place.
Mmm... the others said it was a "locking lever", and you elaborated that it could be used to slide easier the optical instrument along the slotted plate. You said that one could turn the lever by maybe 10 degrees, and this would tighten/untighten the knob allowing the sliding. Is this correct ?
Well, I have the device. It does not work that way. I would need to turn the knob at least by half-turn (180 degrees), in order to be able to shift the camera along the slotted plate.
The "locking lever" is not connected to the "knob" (post). This is why I called it a "washer with lever". When I slightly untighten the knob (post), the lever can rotate freely, independently of the knob. It makes no sense to me to use the lever to tighten the knob only by few degrees. I can easily turn the knob itself.
Also, the tip of the lever has a hole in it. All of this made me thinking that the "lever" could be used for something else, hence I asked the public on the forum. maybe it is used as some kind of stop to prevent the camera from moving further or falling out ?
Edited by va1erian, 14 January 2020 - 09:24 PM.