An ocular consisting of two plano-convex lenses which are formed from similar glass and separated by a space equal to the sum of their focal lengths. This eyepiece is free of lateral chromatic aberration, but because the image plane falls between the two elements it is not suitable for applications involving crosshairs.
SPHERICAL VS. ASPHERIC LENSES
HOW THEY’RE USED IN IMAGING APPLICATIONS
Optical Lenses are often categorized by their shape. Two common surface shapes are spherical and aspherical. Each offers unique characteristics that make it suitable for different use cases.