During more than 35 years in selling camera equipment and 20+ years in professional video production and still photography I have always told my customers to just forget about the digital zoom. It's a cool sounding selling feature, but one with little to no practical use. All you're doing is magnifying a portion of the image, destroying any chance of good resolution or focus. Especially at 100X - 200X magnification, you can't realistically expect any kind of useable image.
RGB Media Services, LLC