Originally posted by Markovo Well, I have seen it couple of times. Not sure that it was here or in other forums. But i sure have a problem with the two lenses i mentioned...
But it's a lens problem, not something specific to the K-30. The 17-50 often have front/back focus issues, with any cameras from all manufacturers.
Originally posted by suraswami Do I need to set it for every focal length or does the camera apply through out the zoom range?
You can only set one adjustment per lens. Thus, you can only set it for one FL. But you should check all FL once the adjustment is done to be sure it didn't screw up focusing at other FL.
Fine adjusting zoom can often be a pain, since the perfect adjustment can vary depending on FL and focusing distance. these variations often make difficult, if not impossible, to perfectly calibrate the lens for all situation. From there, there are some strategies:
1) Calibrate for the worst case (usually longest FL, largest aperture, close focusing) and hope that things will be good enough in other conditions.
2) Calibrate for your most used FL, aperture, and focusing distance. But this means the lens migth be soft in extreme conditions.
3) Calibrate for good-for-all-but-not-perfect-for-anything. Usually done after step 1) or 2) if the results aren't acceptable for other FL than the one use for calibration. The adjustemnt is bring back a bit to get some kind of middle adjustment that is better than no adjustment, at all FL, but not as good as one specific to a FL when used at this FL, but still better at other FL.