Chromatic aberration - a kind of image distortion arising from the non-ideal optics.This phenomenon is due to the dispersion of light when it passes through the lens.It is due to the fact that the rays having different wavelengths (different colors) have a different refractive index.The white beam is decomposed into the spectrum of all colors, and the colors are refracted at different angles and focus on different planes.
Chromatic aberration often lead to the appearance of color contours, spots and stripes that reduce the sharpness of the image and are particularly noticeable in the transition of contrasting objects.A good example is a picture of a tree or a building on the background of the sunny sky.Most strongly this defect is shown at open aperture.
Modern lenses (ie lenses provide chromatic aberration) uses low-dispersion elements that give less refraction and a clearer picture.In Nikon's lenses are denoted by the sign of ED (Extra-Low Dispersion).For the same purpose apply aspheric lens provides images with less such defects.There are also cameras with automatic control aberrations.
But if an existing lens still provides these distortions, there are many ways to deal with them.You can apply filters, edit photos in one of the editors or use plug-suppressing chromatic aberration.How to remove these artifacts using Adobe Fhotoshop quickly and easily?One embodiment is shown below.
Open RAW files in Photoshop, it is picked up by Adobe Camera Raw.Then go to the tab of the Lens Corrections.In parameter Defringe specify All Edges, after which the rims are less bright.Now begin to move the sliders - first Red / Cyan until until fade blue fringe, then Blue / Yellow until the moment when the color of the areola will disappear.All the picture is ready.
Photos in JPEG format can be edited using this filter as the Distort - Lens Correction.It is easy to get rid of the chromatic aberrations, and using Adobe Lightroom.The advantage of the latter is that by treating a picture, you can use the same settings for the entire series with synchronization.
easiest, but not always the correct way to remove these annoying artifacts - translate the picture in black and white format, or initially to shoot in black and white.In addition, knowing that the lens suffers from such a drawback, it is necessary to avoid wide open shots.
most often occur in the chromatic aberration lens having a large multiplicity of the zoom.The thing is that at different focal lengths, these distortions are manifested in different ways, and therefore calculate and compensate for all possible defects in such a complex scheme is extremely difficult.That is why the lenses with a fixed focal length, give a better picture and are usually much more expensive than the "Zuma".
There are also other aberrations of optical systems.When using a spherical lens having spherical aberration due to the difference in the distribution of illuminance in the middle and at the edges of the lens.Expressed this defect in lubrication, resembling a halo.To blur the image and cause aberrations such as coma and astigmatism.Another common defect, especially characteristic of wide-angle and telephoto lenses for - optical distortion, which greatly exaggerates the sense of depth of the frame.It is expressed in straight lines and curvature may be convex and concave.
Most aberrations now it is easy to correct in graphic editors.But sometimes, especially knowing its technology, it is easier to consider them during shooting and avoid possible failures angles.
