By Heinz Richter
Leica is often criticized for being too expensive, some even dismiss Leica cameras as being nothing more than a luxury item.
Of course, Leicas are not for everyone, just like Ferraris, Rolls Royces, Porsches etc. Are not for everyone. They too are out of reach for many because of their cost. But most agree that such cars do offer much more than your everyday Chevy, Kia or VW.
The same is the case with Leica. Their manufacturing process alone sets them apart from virtually all other camera manufacturers. The reason is that almost all other cameras are mass produced, cameras as well as lenses. Leica does not mass produce anything, instead they use a bench making process, where each individual item is made with substantially higher precision.
Especially with lenses this pays off with better performance. There is nothing like a perfect lens. Small deviations from the ideal lens will always happen, so in order to obtain a lens as good as possible, it is necessary to keep any deviations from the ideal to an absolute minimum.
For that reason, Leica applies substantially tighter tolerances than their competition. This starts with the raw optical glass used for their lenses. The various types of glasses necessary to make a lens must have a certain refractive index as well as a specified amount of dispersion.
Leica applies a standard of ±0.0002% for the accuracy of the refractive index. This compares to the international standard of ±0.001% as applied by other lens manufacturers. The accuracy of the Abbe number, the measure for dispersion, is ±0.2% for Leica compared to ±0.8% internationally.
These much tighter tolerances continue during the grinding process of the individual lens elements. Leica allows minimum production tolerance of no more than ¼ lambda or ¼ of the average wavelength of light which corresponds to approximately 500 nanometer or 0.0005mm for the accuracy of the lens surface. However, with some lens elements this accuracy is set for 0.0001mm or 0.1 μm (micrometer). In comparison, the tolerances applied by other lens manufacturers are ½ lambda or 0.001mm or 1 μm . Similar tolerances are used for the thickness of the elements and proper centering along the optical axis.
These are just a few examples of the extra input that Leica lenses receive. However, this would be useless if extremely tight tolerances were not applied mechanically as well.
The mechanical tolerances applied by Leica must conform to a minimum of 1/100 mm or 10 micrometers which equals less than 0.00039 inch for the accuracy of the lens mounts of both cameras and lenses, but also for the accuracy of the focusing mount of their lenses and for the rangefinder in the Leica M-type cameras. The same tolerances used to be applied to the accuracy of the focal plane in the Leica analog cameras. These needed to be increased substantially for the positioning of digital sensors since, unlike with film, sensors are totally flat. Other manufacturers apply tolerances of about half of these measurements. For the focusing mounts of all manual lenses, initial testing is done by machine. However, the threads of the focusing mechanism of these lenses are always finished by hand with hand grinding and polishing for one hour. These final test are up to an experienced individual who is trained to feel even the slightest imperfections in the smooth operation of the focusing mount. No machine is capable of doing that.
The next time anyone has a negative reaction to the cost of Leica cameras and lenses, let’s not forget that there is much more to that than a company selling luxury items.
For in depth information on this go to: Making Cameras and Lenses the Leica Way
For other articles on this blog please click on Blog Archive in the column to the right
For other articles on this blog please click on Blog Archive in the column to the right
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