Archived posting to the Leica Users Group, 2008/04/21
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Integrated Circuits have features that are in the area of a few tenths of Microns thick. Translation: The focal plane of the sensor is less than a Micron in thickness. If t he focused image does not fall in this plane, it is out of focus. If the lens focus plane moves 120 microns,......... the M8 will ALWAYS be out of focus ......at F5.6. Remember, all we did was move the Aperture ring from F1 to F5.6......not the subject nor our position nor the focus ring on the lens. Maybe now it is easier to understand why the M8 and the Nocti are not the best combination....... BTW, film has a thickness of about 1000 times thicker. As was previously stated, the Nocti works fine on film....... Marty.....Thanks for the numbers...... Frank Filippone red735i@earthlink.net Focus shift is important in all optical systems where spherical abberrations are the main limiting factor for resoltuion. This is the case for the Noctilux. At going from f1 to f2 the Noctilux focus shifts 74 microns closer than the gain in depth of field. Between f2 and f5.6 the shift is 120 microns greater than depth of field. This is enough to visibly lower contrast in enlarged prints due to slight softening. Resolution is harder to assess, but Erwin makes it clear that it was visible on the test bench.