The LCD screen of the camera will show the image as seen by the lens. If there is low or no light source or ambient light, the subject will be unclear or not visible on the LCD screen prior to taking a picture. In some instances the LCD screen may be black. This is normal operation and it happens for most types of cameras even from other manufacturers.
If the camera being used has an AF Illuminator or Red Eye Reduction feature, set it to on so that the camera illuminates the subject prior to taking the picture.
NOTE: For model-specific information regarding the AF Illuminator and Red Eye Reduction feature, refer to the instruction manual supplied with the camera. Manuals are posted on your model support page.