Nesta última foto, colorida que foi tirada pela esquerda há aberração cromática nas árvores da direita que estão contrastando com a luminosidade do céu?(observar canto superior do lado direito da foto)
Percebe-se uma borda arroxeada entre o caule e a luz intensa do céu.
Poderiam confirmar se isso é aberração cromática?
Este defeito pode ser contornado com uma menor abertura ou maior velocidade no disparo ou é problema de ótica da máquina mesmo?
Valeu!
É o famoso CA, problema inerente ao projeto da lente(lente barata),
o maximo que da para fazer é editar no PhotoShop...
**Nesta** foto corrigi assim
CA
http://www.vanwalree.com/optics/chromatic.htmlCA em câmeras digitais
http://www.botzilla.com/photo/g1chroma.htmlThe eight optical defects and what the cameraman can and cannot do to correct the defect.
1. Astigmatism - The inability of the lens to bring to focus both vertical and horizontal lines on the same plane. Astigmatism is caused by axial rays (not parallel to the lens axis). It will appear that lines of equal density (darkness) are less dense horizontally or vertically. Astigmatism is improved by stopping down the lens (smaller lens opening, larger F number).
2. Coma - coma causes parallel oblique rays passing through a lens to be imaged (focused) not as a point, but as a comet shaped (oval) image. Coma can be improved by stopping down the lens.
3. Curvature of Field - The plane of sharpest focus becomes curved, not flat. It is caused by rays from the outer limits of the subject plane coming to focus nearer to the lens than the axial rays (image comes to focus in curved shape, away from the CCD). This defect is not improved by stopping down the lens.
4.
Longitudinal Chromatic Aberration - The inability of a lens to focus all colors (wavelengths) at the same plane on the lens axis (shorter wavelengths come to focus in front of the CCD, longer behind).
This defect is not improved by stopping down the lens. This is normally only noticable in long telephot lenses. It is reduced by the use of special glass elements, referred to as ED, ID, LD or Flourite.
5.
Lateral Chromatic Aberration - lateral displacement of color images at the focal plane (CCD). Caused by different sizes of images by procuced by different colors even though the image is all on the same plane (CCD). Produces color fringing of red or blue.
Not improved by stoping down.6. Spherical Aberration - Inability of all rays to focus at the same point. Marginal rays (at the edge) through the lens come to focus closer to the lens than do paraaxial rays (rays parallel to the axis or center). This causes the focus to drift as you stop down the lens. This may be part of the XL1 focusing problems. However, it's just my opinion.
7. Distortion - distortion causes the image of a straight line, at the edges of the field (CCD) to bow in or out. Bowed in, pincushion, bowed out barrel distortions. Produced by variations of magnifications over the field of the lens, particulary at the ends of its range (max wide angle, max telephoto). It does not effect sharpness, only shape of the image. It is not improved by stopping down. Very common in extreme wide angles and lenses with WA adapters.
8. Flare - Flare is non-image forming light. Reduces contrast and color saturation. Flare is caused by very bright subject areas and produces internal reflections in the lens. Stacking of filters can increase flare. Lens coatings by the Mfg. keeps flare to a minimum. The use of a suitable hood (not the stock hood) can also aid in reducing flare.
9. Ghost Images - Not a true defect put is seen quit often and sometimes confused as one. Distinct images, usually in the shape of the diaphram or a very bright light source included in the scene. Caused by high intensity light producing rays which bounce around in the lens and form an image. Often multiple images appear in a row across the scene, starting at or near the source. Ghost images can be reduced by the use of a suitable lens hood.
