Vortex Skyline ED Spotting Scope - Angle. Capture exacting views most precisely with the Skyline ED spotting scope. Vortex uses extra-low dispersion (ED) glass in the optical system of this scope to correct for chromatic aberrations. The result? Bright, sharply defined images with correct colors throughout the powerful 20-60x zoom range. And, with just a twist of the eye cup, you'll take in the most pleasing, wide-field views in comfort with eyeglasses, too!