Originally posted by aleonx3 When you press the green button, the screen does not go black (the mirror would not be up). The problem with the OP is
likely a wrong setting in the drive mode with 2 second delay; resetting the drive mode back to single frame would likely solve the problem; just my thought and suggestion anyway...
If the K-r operates like the K-x (and the K-m before it) the mirror cycles when you press the green button with a M lens. Furthermore, you don't need to have the Green Button set to Green Button. You can press the AV +- button and that will set the P Line. You can set the Green Button to do something else, like Optical Preview.
When you are using an A lens in Manual mode you do have to use the Green Button to set the exposure because the AV +- button switches between shutter speed and aperture. With an A lens the mirror does not cycle when you press the Green Button.