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Old 04/03/12, 03:40   #14 (permalink)
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Timmyjoe's Avatar
Join Date: 07/06/10
Location: Chicago
Posts: 1,620
Default Re: Leica Screw Mount Lens Issue

Well it turns out that, as usual, things are a bit more complicated than they originally appeared. Here is what I found out and what I did to remedy the problem.

I posted this on a number of forums, and a camera service person commented that he had seen this before, and he said in particular on iiif cameras serviced at the factory. Seems that when you are reassembling the camera, and you are putting the front plate on, you need to go back and loosen a couple of brackets you've already tightened, otherwise you put undo torque on the front plate, causing it to twist and not sit flat.

That twist is transmitted to the lens mount flange, which transmits the twist to the lens when it is mounted, which binds up the lens. That's my understanding at least.

I found the information and image I posted above in the National Camera service manual for the iiif. Again, here is how they tell you to reassemble the front plate.

"The screw at the bottom of the front plate (which is slightly shorter in length than the other four front plate screws (screw G)) and the uppermost screw around the lens opening (screw D) both pass into anchor plates on the inside of the focal plane. Before installing these two, loosen the screws which secure the anchor plates (one at the end of the flat retard rod spring and two within the accessory shoe cavity). Now, align the threaded holes in the anchor plates with their corresponding holes in the front plate and replace the two front plate screws. Tighten down the anchor plates once again and install the remaining three screws around the lens opening which thread into the light shields."

Here's an image of the front plate with the screws identified by letter.

On my camera I found out I could remedy this by taking the camera apart, loosening screw D and G and then loosening the anchor plate screws, then tightening screw D and G, and then tightening the anchor plate screws?

I then put the camera back together, reset the FFD with a collimator, and reset the rangefinder at infinity. Now she focuses nice and smooth.

Very Happy.

Thanks to everyone for your input.
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telewatt (04/03/12)