JTX Lens & Chromatic Aberration

Chromatic aberration (or CA) is a type of distortion in which a lens is unable to perfectly focus all colors of light to the same convergence point. It occurs because lenses have a different refractive index for different wavelengths of light. In other word, a lens will bend different wave lengths (or colors) of light in differing amounts. This results in colors separating or “fringing”.

In a prism based anamorphic lens, the CA occurs along the horizontal axis. The best way to detect the effects of CA is to display a test pattern with vertical white lines (1 pixel width) on a black field.

CA is always going to be the greatest at the far left and right edges of the projected image. In the center of the image CA effectively disappears. This is fortunate as in almost all instances the attention of the viewing audience is kept toward the center of the screen. Even at the edges of the projected image, where the effects are greatest, CA often goes undetected for those immersed in a movie.

HOW TO MINIMIZE THE EFFECTS OF CA
All two prism setups intrduce some amount of chromatic aberration, this is simply their nature. However, the extent to which CA is introduced is affected directly by the throw ratio. The longer the projectors throw the less CA is introduced, likewise, the shorter the projectors throw the greater the effects of CA.

This means that to minimize the effects of CA, the projector needs to be positioned as far to the rear of your theater as possible, but still allowing for desired image size. In the end, the amount of CA that is caused by the JTX Dual Prism Anamorphic Lens will depend on each individual’s theater setup.