Red 610nm longpass filter with steep absorption edge.
- Passes the H-alpha line from the visible spectrum.
- Blue and Green lights is almost completely blocked increasing contrast between the light and dark bands on Jupiter and Saturn.
- Most interesting filter to use for observing the polar caps of Mars.
- An optimum filter for daily observation of all the planets.
- Multi-coated for max contrast â€“ no reflections, scatter or dimming.
- Planeoptically polished to within 30 seconds of arc for a sharp image at high magnification with non-ageing sealed coating edges.
- Both sides 7-layer AR coating with only 0.25% residual reflection per surface. This is the most antireflective that has ever been undertaken with color filters.