When focusing is not possible in AF mode, use manual focus. You can specify the general focus position and then press the shutter button halfway to have the cmaera determine the optimal focual position near the position you specified.
Choose [MF]
Press the button, press the buttons to choose , and then press the button.
and the MF indicator is displayed.
Specify the general focual position
Referring to the on-screen MF indicator (1), which shows the distance and focual position, and the magnified display, press the buttons or turn the dial to specify the general focual position, and then press the button.
Fine-tune the focus
Press the shutter button halfway to have the camera fine-tune the focual positon (Safety MF)
button, press the 
buttons to choose 
, and then press the 
button.
dial to specify the general focual position, and then press the