http://www.pentax.jp/english/support/digital/k-7_s.html

    * Lens Correction (Distortion, Lateral chromatic aberration) is settable for below FA limited lenses.
      smc PENTAX-FA 31mmF1.8AL Limited
      smc PENTAX-FA 43mmF1.9 Limited
      smc PENTAX-FA 77mmF1.8 Limited
    * Improved usability by optimize the program of vertical position judgment.
    * Improved stability of recording movie for some SDHC Memory card.

多谢，才知道，刚升级好像暗处的对焦速度快了些。