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Sorry for the delay and thank you for your patience. My name is Michael. I will be helping you with your question today. Please let me know if there as any additional information that you feel might be pertinent to your question. If I don't hear back from you, I'll provide the best answer I can based on the information you've given so far. You will still be able to reply with additional information or questions at any point during our conversation, and I'll revise the my answer accordingly.
Of you start in standby on the K3 and then press the left arrow, you will see the white balance presets from which you have to choose. Just select from those and continue with the photos.
If that isn't exactly what you are looking for, let me know, along with any additional information, and I will help you get it done.
If you look on page 53 of the manual... adjusting white balance manually... that shows you the exact steps. You can measure the white - you cannot measure various levels of gray which it sounds like you may want to do. All you can do is set the white reference point.