Editing Optical aberration (section)

===Monochromatic aberrations===

The most common monochromatic aberrations are:

*[[Defocus aberration|Defocus]]
*[[Spherical aberration]]
*[[Coma (optics)|Coma]]
*[[Astigmatism (optical systems)|Astigmatism]]
*[[Field curvature]]
*[[Image distortion]]

Although defocus is technically the lowest-order of the optical aberrations, it is usually not considered as a lens aberration, since it can be corrected by moving the lens (or the image plane) to bring the image plane to the optical focus of the lens.

In addition to these aberrations, [[Piston (optics)|piston]] and [[Tilt (optics)|tilt]] are effects which shift the position of the focal point.  Piston and tilt are not true optical aberrations, since when an otherwise perfect wavefront is altered by piston and tilt, it will still form a perfect, aberration-free image, only shifted to a different position.