Leica rumors published a lengthy article titled
“The Mystery of Leica Pricing Explained by J Shin.”
It dispels the criticism Leica often receives for their pricing policies. It shows that Leica, just like everyone else, has to follow economic principles to be a viable company.
However, what is hardly touched on at all is the fact that Leica’s production methods are different from virtually any other camera or lens manufacturer. It is a fact that Leica does not mass produce any of their items. This is necessary to be able to reach the performance levels of their equipment. No mass production will ever be able to match the overall tolerances applied to Leica cameras and lenses. Yet it is those tolerances that are necessary to elevate overall performance to optimum levels.
It is often said that Leica cameras and lenses are hand-made. That is misleading. Leica uses a bench made process where individual manufacturing and assembly steps are done by individuals on separate desks or benches. This enables each manufacturing and assembly step to be immediately accompanied by a test. Only if this test proves the manufacturing or assembly step to be within set tolerances is the item allowed to advance to the next step. If not, the necessary corrections are made or, if that is not possible, the item is rejected. This is considerably beyond mass production where applied tolerances are necessarily lower and only periodic spot checks are done.
I have personally witnessed these procedures at the Leica plants I have visited. For instance, lens manufacturing starts with the grinding of individual lens elements. Only one element is ground at a time. This starts with a blank disc which is inserted into the grinding machine. The first few steps are automated. All individual grinding steps are done with different machines. Once a step is completed, the lens element is moved to the next grinding machine by a technician. After the third or fourth step the lens element is checked for accuracy and, if necessary, additional grinding is done before the lens element is moved to the next step. This continues throughout the entire grinding and polishing process. The criteria checked are sphericity, the accuracy of the lens surface curvatures, centering, and lens element thickness, just to mention some of the most important ones. Once a lens element has passed all of these steps and once they are thoroughly cleaned, they are coated with the anti reflection coating. To my knowledge, only Leica considers this as part of the manufacturing steps. With other words, the thickness of the coating, which is only in the range of a few molecules, is included in the measurements for lens element thickness and sphericity. Once finished, the lens elements are optically tested to assure that they are within proper optical tolerances. In addition, any allowable deviances from the ideal are recorded by a 0 or a +/- designation of for example -3 or +3. The elements are sorted accordingly.
The mechanical parts of the lenses are made along the same guide lines. Each manufacturing step is immediately accompanied by a check and the correction of any deviances if necessary. For instance, I observed a part of a lens being made on a small lace. The test apparently proved that not all was within tolerances, and the lens part was further worked on. This went back and forth several times until all was perfect. Not until then did work proceed to the next item.
During the assembly of a lens individual lens elements are not assembled at random. Instead the deviances of individual elements from the ideal are compensated for with other elements with similar deviances. For instance, a +3 element might be paired with a -3 one. It should be noted here that all these deviances have to be within the extreme tolerances set by Leitz. The end result of all this precision is generally lenses with a noticeably higher performance than those from competitors, but also substantially lower performance differences from lens to lens.
The manufacture of Leica cameras follows the same principles. Needless to say, such attention to detail and precision does come at a price. If these higher prices for Leica cameras and lenses are worthwhile is something that everyone has to decide for him or herself. However, these steps are necessary to set Leica apart from the crowd, so to speak.
Here is a short list of some tolerances applied by Leica compared to their competition:
Mechanical tolerances of cameras and lenses
Leica 1/100 mm (1/2540 inch), general industry standard 1/1000 to 1/1500 inch.
Optical tolerances
Accuracy of refractive index of glass: Leica standard +/- 0.0002%, international standard +/-0.001%.
Accuracy of Abbe number (dispersion): Leica standard +/- 0.2%, international standard +/- 0.8%.
Individual Lens Elements
For the manufacture of individual lens elements Leica allows production tolerance of no more than ¼ lambda or ¼ of the average wavelength of light which corresponds to approximately 0.00015mm. (0.000005906 inch). International standards are ½ lambda or 0.0003mm (0.00001181 inch).
For more information go to:
OPTICAL GLASSES: http://www.blogger.com/blogger.g?blogID=1320126156594375642#allposts
MANUFACTURE AND PERFORMANCE OF PHOTOGRAPHIC LENSES:
LENS TESTS
IN MEMORY of the LEITZ GLASS LABORATORY
No comments:
Post a Comment