Originally posted by hcc I think that you should compare your camera with another screw-drive camera. The DA18-55 should focus relatively rapidly (using the OVF) and that what I would check.
If you could, get in touch with another Pentax user and check how his/her camera focus works,
You want first to ascertain that the problem is the camera , not the lens. For that I would recommend to use a Pentax lens (not a 3rd party), preferably a short lens (DA limited or DA18-55mm), and use the optical view finder (OVF) in broad day light conditions. If you believe that the camera is really the issue, reset all the camera settings. Then set centre focus point.
Hope that the comment may help.
actually i am thinking about how i can improve the focusing speed effectively (by lens or by DSLR )