I just saw a K20 by default have the af correction menu on the camera while the Pentax K-x dont have. Ive been searching until i found this one, so i just post it here for K-x users (including me) This thread is to fine tune your focusing front and back focusing.
Using Pentax Kx debug mode to do a focus adjustment
Create a plain text/ascii file named "MODSET.492" with just one text line in a root folder of your SD flash card:
[OPEN_DEBUG_MENU]
the line must end with CR/LF (as it is a customary w/ "MS Windows" text files).
Turn on the camera while holding <+/-(Av)> button pressed.
Enable the mode through the first menu item "DEBUG MODE" (press "ISO" arrow-button to change "DIS" to "EN").
Press "OK" button, the LCD screen will switch itself off.
Press "MENU" button.
Scroll to the "TEST MODE" tab that will be visible now (it was hidden before).
Scroll down to "AF TEST" menu item in the "TEST MODE" tab and select it.
Do the necessary corrections with "FocusCorr" slider.
Save the adjustments by pressing "OK" button, the LCD screen will switch itself off.
Press "MENU" button again.
Again scroll to the "TEST MODE" tab that will be visible now (it was hidden before).
Scroll down to "DEBUG MODE DISABLE" menu item in the "TEST MODE" tab and select it to return back to the normal camera operation.
Switch the camera OFF and ON again.
Some things to remember - any changes that you will do using "FocusCorr" slider are cumulative - so if you will change it to "-50" once and then to "-30" next time - it will be "-80", not "-30". You need to change it to "+20" to make the correction equal to "-30" if that was the absolute value that you want. Also you do need to log out (disable) from debug mode to do the testing, while you can make test shots immediately after doing the adjustment I think that AF adjustments are not effective w/o powercycling the camera. Make all the changes with a freshly charged set of batteries if not using DC power. Making negative ("-") adjustments to "FocusCorr" slider will move the focus point away from you (camera) - to correct FF/front focus situation (when originally the camera focuses before the target) and making positive ("+") adjustments to "FocusCorr" slider will move the focus point closer to you (camera) - to correct BF/back focus situation (when originally the camera focuses behind the target). You can keep the "MODSET.492" file all the time on your flash cards - just do not forget to remove the flash card if you will neeed to send your camera to the service for whatever reason.
Using Pentax Kx debug mode to do a focus adjustment
Create a plain text/ascii file named "MODSET.492" with just one text line in a root folder of your SD flash card:
[OPEN_DEBUG_MENU]
the line must end with CR/LF (as it is a customary w/ "MS Windows" text files).
Turn on the camera while holding <+/-(Av)> button pressed.
Enable the mode through the first menu item "DEBUG MODE" (press "ISO" arrow-button to change "DIS" to "EN").
Press "OK" button, the LCD screen will switch itself off.
Press "MENU" button.
Scroll to the "TEST MODE" tab that will be visible now (it was hidden before).
Scroll down to "AF TEST" menu item in the "TEST MODE" tab and select it.
Do the necessary corrections with "FocusCorr" slider.
Save the adjustments by pressing "OK" button, the LCD screen will switch itself off.
Press "MENU" button again.
Again scroll to the "TEST MODE" tab that will be visible now (it was hidden before).
Scroll down to "DEBUG MODE DISABLE" menu item in the "TEST MODE" tab and select it to return back to the normal camera operation.
Switch the camera OFF and ON again.
Some things to remember - any changes that you will do using "FocusCorr" slider are cumulative - so if you will change it to "-50" once and then to "-30" next time - it will be "-80", not "-30". You need to change it to "+20" to make the correction equal to "-30" if that was the absolute value that you want. Also you do need to log out (disable) from debug mode to do the testing, while you can make test shots immediately after doing the adjustment I think that AF adjustments are not effective w/o powercycling the camera. Make all the changes with a freshly charged set of batteries if not using DC power. Making negative ("-") adjustments to "FocusCorr" slider will move the focus point away from you (camera) - to correct FF/front focus situation (when originally the camera focuses before the target) and making positive ("+") adjustments to "FocusCorr" slider will move the focus point closer to you (camera) - to correct BF/back focus situation (when originally the camera focuses behind the target). You can keep the "MODSET.492" file all the time on your flash cards - just do not forget to remove the flash card if you will neeed to send your camera to the service for whatever reason.