What is the difference between achromatic plan, achromatic semi-apochromatic, and apochromatic objectives?
An achromatic objective corrects for color and has a flat field across the central 65% of the image. It's usually a pair of lenses. Semi-plan (semi-planar, sometimes called micro-plan) objectives have an 80% flat field. They can either be two lens element achromats or three or more element apochromats.Nov 24, 2008
An achromatic objective corrects for color and has a flat field across the central 65% of the image. It's usually a pair of lenses. Semi-plan (semi-planar, sometimes called micro-plan) objectives have an 80% flat field. They can either be two lens element achromats or three or more element apochromats.Nov 24, 2008
