Light Pollution-Rejection Ratings

Key: E = excellent, VG = very good, G = good, F = fair, N/A = not applicable. All measurements are averages taken from manufacturers' published curves (or independent testing reports when available). Passband widths are measured at the 50% transmission points. The average light transmission and rejection figures are only a guide to relative performance, not a guarantee of performance, as individual filters will vary due to production tolerances during the fabrication of each 30 to 40 layer filter. Under light pollution rejection ratings, above, the lower the transmission number in parentheses, the more effective the filter is at blocking pollution. Under desirable passband transmission ratings, below, the higher the number in parentheses, the brighter the images. The greater the difference between the figures, the better the contrast of the nebula against the darkened sky.