Und das:
Das möchte ich auch noch anhängen, leider wieder in Englisch.
Kurz zusammengefaßt:
Früher hat man die Objektive lückenhaft getestet, mit Problemen auch Fokusfehler zu finden.
Jetzt hat man aus Merrill-Sensoren eine hochauflösende Testeinrichtung gebaut und testet jedes der neuen Objektive.
Vielleicht sind deshalb die neuen wirlich alle im Fokus.
Ich kann nur hoffen, daß meine vier Sigmas in Aizu an einem ähnlichen Tester waren, und daß jetzt alle Linsen, die vom neuen Sigma-Tester kommen, auch an allen meine Kameras laufen.
Ich befürchte allerdings, daß es den neuen Tester noch nicht in Rödermark gibt.... :fragezeichen:
http://www.imaging-resource.com/new...ns-factory-precision-production-from-the-insi
When everything has been assembled and the lens is complete, the final step is testing. Testing and QC have always been key parts of Sigma's process, but there's been a recent & significant upgrade in this area. For a long while now, Sigma has spot-checked lenses on an MTF tester of their design, which employed a Kodak image sensor. As digital SLRs and CSCs have evolved to ever-higher resolutions, though, the old system began to show its age, in that it wasn't able to discriminate critical focus as well as some of the camera systems Sigma's lenses were being used on.
Searching for a better solution, the Sigma engineers had an epiphany when they realized that they already had an excellent, very high-resolution sensor at their disposal -- namely the Foveon chip used in their flagship SD-1 camera. The only catch was that that sensor was an APS-C sized one, smaller than the full 35mm frame that many of Sigma's lenses cover.
The solution, of course, was to cover the frame piecemeal, using four individual, overlapping exposures to achieve full-frame coverage. One of Sigma's clever young engineers developed a combined software/hardware solution that did this (sorry, I didn't get the engineer's name; he surely deserves credit), the result being Sigma's new A1 MTF-measuring system. A housing encloses the sensor assembly and the motorized stage that moves the sensor either successively to the four corners of a full-frame area, or to the center of the frame, for testing lenses designed for cameras based on either APS-C or Micro FourThirds sensors. A universal lens-mounting system on the front of the housing accommodates lens mounts for Sigma, Canon, Nikon, Pentax, Sony (both A- and E-mount) and Micro Four Thirds systems, precisely matching the flange-sensor distance spec for each.
Unfortunately, I wasn't allowed to take photos in the area where the A1 systems were being built and used; the work being done there was a bit too proprietary for public dissemination.
What's particularly remarkable about the new A1 MTF-testing systems is not so much the systems themselves (which are exceptional enough in their own right), but the way they're being used. All of Sigma's new "Global Vision" lenses are being tested 100% on A1 systems, with any that don't pass muster across the entire frame being rejected. As far as I can tell, this is an unprecedented level of QC for the lens industry, and sample variation among the new Global Vision optics should be dramatically lower than we've seen thus far from the industry as a whole. The engineer behind the A1 system has built 30 of these systems to date, for use in production testing, with more in the pipeline.
Mr. Yamaki noted that the new A1 testing system gives them a much finer ability to discern minor variations in sharpness, and smaller amounts of decentering of a lens' elements. Sigma's lens designs have always been characterized by much better than average sharpness at a given price point, but the new A1 testing system ensures that all of the Global Vision lens models will perform closer to design specs than has previously been possible. Mr. Yamaki said that using the A1 system and the more stringent quality controls it enables has reduced their manufacturing yield somewhat, but he's happy, knowing that they're producing lenses with an unprecedented level of quality and consistency.
