Leica M lens production
Of course the M rangefinder cameras are just part of the story - equally important to the whole Leica experience is the quality of the lenses. All of the shaping and coating of the glass elements, and the assembly and testing of the lenses, takes place at the Solms factory, and we were given a tour of the fascinating process that converts metal and glass to precision optics.
Grinding and shaping
The first stage in making a lens is the shaping of the optical glass into the individual elements which, when combined, make a functional lens.
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The optical glass that will be used to make the lenses arrives in the factory as 'blanks' - roughly-contoured discs ready for shaping. |
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These are the machines used for grinding the blanks to give conventional spherical-surfaced lens elements. Typically three steps, each taking 5 minutes, are required to produce properly-shaped elements. |
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Superficially similar, but altogether more complex machines are used to grind those lens elements which utilise aspherical surfaces. Unlike most manufacturers, Leica doesn't employ the cheaper methods more commonly used for mass-production of aspherical elements (glass molding, or hybridisation with aspheric plastic surfaces which are molded onto the glass). |
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Here's a closer look at the inside of a grinder. The two flexible nozzles direct special grinding fluid onto the surface of the glass during operation. |
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In a display case in a corridor outside the production area is this simple but effective demonstration of the difference between spherical and aspherical surfaces. |
Cementing, coating and lacquering
Once the elements are ground they go through further finishing processes. Two elements may be cemented together to form a group; and all of the glass surfaces are coated to minimize the reflection, rather than transmission of light (this is particularly critical with fast, multi-element lenses such as the 50mm F0.95 Noctilux). The edges of the lens are also coated in black lacquer to reduce internal reflections.
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This is the process by which two elements are fixed together to form a group. The contact surface is coated with UV-activated cement, and the two lenses are precisely centered relative to each other. A quick flash of UV light then cures the cement and fixes the glass together permanently.
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Here elements are being racked up ready for coating. They are thoroughly cleaned first, of course. |
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This is an oven used for coating the lenses. The process is known as 'vapor deposition' - the coating compounds are vaporized at temperatures up to 250 C, and then deposit evenly on the lens surfaces to give coatings of uniform thickness.
Of course rigorous standards of cleanliness are required - in this shot the oven is being cleaned out between runs. |
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Here we see the edge of a 2-element group (part of a 50mm F0.95 Noctilux) being hand-coated in black lacquer. A painstaking job and not one, we suspect, for the caffeine addict. |
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Coated and lacquered elements or groups are then fitted into metal surrounds ready for assembly into completed lenses. Here's a load all racked up and ready to go. |
Assembly and testing
Once the individual optical elements are finished, the process of assembling them into complete lenses can begin.
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