Simple paper, uncorrected gel glasses, cannot compensate for the 250 nanometer difference in the wave lengths of the red-cyan filters. With simple glasses, the red filtered image is somewhat blurry, when viewing a close computer screen or printed image, The (RED) retinal focus differs from the image through the (CYAN) filter, which dominates the eyes’ focusing. Better quality, molded acrylic glasses frequently employ a compensating differential diopter power (a spherical correction) to balance the red filter focus shift relative to the cyan, which reduces the innate softness, and diffraction of red filtered light. Low power reading glasses worn along with the paper glasses also sharpen the image noticeably.
Dispersive Prism
The correction is only about 1/2 + diopter on the red lens. However, some people with corrective glasses are bothered by difference in lens diopters, as one image is a slightly larger magnification than the other. Though endorsed by many 3D websites, the diopter “fix” effect is still somewhat controversial. Some, especially the nearsighted, find it uncomfortable. There is about a 400% improvement in acuity with a molded diopter filter, and a noticeable improvement of contrast and blackness.
Wow. Very well explained.