Aspheric magnifiers unlike spherical magnifiers provide an "orthoscopic" image. Donegan aspheric lenses are shaped with a variant radii calculated to produce a sharp image right to the edge of the lens. This allows for distortion-free viewing over the entire lens area with greater magnification than is possible with a normal spherical lense.
Powerful 2'' x 4'' aspheric lens provides 3X magnification. Mounted in a prefocused stand. Fits conveniently over surface to be viewed.