With any given scope there is a maximum useful amount of magnification, and on most nights the atmospheric turbulence will limit you to far less. For planets with the ETX-90, you'll probably find that about 125x to 150x is good for planets, and above that will be disappointing most nights. For fainter deep space objects, lower powers and very dark skies are your friends. The ETX is probably best at viewing the Moon, Jupiter, Saturn, and a few of the brighter Messier objects (in the winter, check out M42). It isn't made for the faintest fuzzies, which require much more aperture. Portabilty and relatively well made optics are plusses for the ETX--that, plus it can be used as a decent daytime scope. Small aperture is its limiting factor at night.