Its construction is extremely rugged to allow it to withstand all the handling that is typical of airline travel. Images of stars and planets are presented in their natural colors, and daytime objects appear sharp and contrasty without annoying purple fringes. The optical design of the 105mm EDT objective is identical to the StarFire EDT refractors. It consists of a positive element of Super ED glass surrounded by two matching hard crown meniscus lenses. The two outer elements are chosen so that the combination is free of coma, sphericalaberration and other higher-order aberrations.
All surfaces are spherical, which results in a very smooth overall figure.
Under steady viewing conditions, you will see a hard white Airy disc at focus surrounded by the first diffraction ring. Inside and outside of focus, you will see an evenly illuminated, expanded disc with concentric Fresnel rings, the outermost ring brighter and wider than the rest. On most nights, the settling down time for the lens is 10 to 15 minutes, and even in sub-freezing conditions, it rarely takes more than 45 minutes to stabilize. The 105 Traveler EDT is an awesome performer both at night and during the daytime using powers as low as 12x or as high as 400x. During the daytime, delicate detail and vivid colors of flowers and wildlife are a true joy to observe.