There are a great deal of settings that can cause these unexpected results. Most of them are the result of the inability to focus when in any of the auto focus modes.
It may be a good time to do a RESET on the camera to restore the settings to factory defaults. This can be done by pressing and holding the 2 buttons with GREEN DOTS for a few seconds. One button is on the lower left of the rear display and the other is on top - near the shutter release button. You can
download and read about this reset feature in the manual on page 11.
Additionally, you can read a review and learn about some helpful settings to try on your D40
here. I hope this was helpful!
×