DESC: The "ED100" delivers images remarkably free of chromatic aberration, thanks to its fully multi-coated 100mm objective doublet. It's crafted with one element of FPL-53 extra-low dispersion "ED" optical glass from Japan. The 100mm aperture gives it 56% greater light grasp than our ED80. And the 900mm focal length (f/9.0) is ideal for visual planetary and lunar study and excels for imaging work as well.