Chuck-
There is a direct correlation between optical zoom and image quality, whether you are talking about camera lenses, binoculars, riflescopes, microscopes or telescopes. You simply get a better quality image with higher power optical lenses because the optics, not the software, brings the image closer to the viewer. The higher the power/magnification, the closer you can get to your subject and the better the image quality.
Megapixels are created digitally and can be manipulated by the software on your camera or your computer to a higher or lower density, but they can't create a better image than what the light passing through the optical lenses created in the first place.
Skatr,
I agree with you about digital magnification not producing as high quality as optical magnification. I think that's well known. But image quality capability is not necessarily about magnification, it's about resolution within the captured image no matter the magnification, IMO. For example, I have a 60mm MicroNikkor that has much better image quality, whether close or distant subjects, than my 400mm or any other lens I have. If I back up with the 400 and take a picture, then take the same picture closer to the subject with the 60mm, capturing the same actual area of the subject, my 60mm will be of superior image quality hands down. My point is, image quality and magnification are typically defined as separable.
