Depth of field is adjustable for all by resizing the aperture (a.k.a. the "eyelid" mechanism). Try a higher f-stop ("squint") if you're having trouble with it.

However, the focal point with respect to the sensor is indeed miscalibrated in some units, and good units can become miscalibrated over time. There are some after-market correction devices available.

Higher f-stops are especially helpful for astigmatism correction. Overuse of the increased non-autonomic f-stop has been associated, however, with distress signals being generated by nearby actuators, resulting in a feedback loop of reduced f-stop to decrease said distress signals.

:)