The resolution number on the right side of the screen also becomes smaller as you digitally zoom. For example, 4.1MP appears in place of 6MP, indicating that the image is being reduced to a size of 4.1 Megapixels.
3.When the image is at the desired size, press the Shutter button halfway down to lock focus and exposure, and then press it all the way down to take the picture.
4.To return to optical zoom, press Zoom Out 
on the Zoom lever until digital zooming stops. Release Zoom Out 
, and then press it again.
NOTE: You can disable digital zoom in the Setup Menu (see Digital Zoom on page 126).
NOTE: Digital zoom reduces the resolution of an image, so your picture will tend to be more grainy than the same image taken with optical zoom. In situations where you need higher quality (such as for printing), limit the use of digital zoom.
NOTE: Digital zoom is not available while recording video clips, nor when in Panorama shooting mode.
46 HP Photosmart R717 User’s Manual