What's the difference between Variable Polarizing filter, the Neutral Density Moon filter, and the Moon filter?
January 3, 2019
Neutral Density Moon Filter
The 94105 Neutral Density Moon Filter is a filter that attaches to a 1.25” eyepiece that lowers the amount of light entering the eyepiece by 87%. In a telescope the Moon can appear extremely bright and even be uncomfortable to look at. This filter only allows 13% of the telescope’s light to reach the eyepiece, making it a lot more comfortable to view. Unlike color filters, the Neutral Density Moon filter affects all colors of the visible spectrum evenly, darkening the image without shifting the color. Some less expensive Moon filters are really #58 Green filters. While they work well for this application, the ND filter gives a true color image. This filter is also good for helping to cut glare and increase contrast when viewing bright planets like Venus or Jupiter, or even to dim bright stars when splitting close double stars. The filter is glass with an aluminum cell that attaches to 1.25” eyepieces and is threaded on both sides so it can be stacked with color filters.
Variable Polarizing Filter
The 94107 Variable Polarizing filter uses two polarized elements that can be independently rotated with respect to each other. This filter, like the Neutral Density filter, helps to lower the amount of light getting through to the eyepiece without effecting the color of your image, but has the advantage of adjusting how much light gets through. By turning the lower filter you can adjust the light transmission from 1% to 40%. This filter is perfect for dimming your image of the Moon and splitting double stars where one star is significantly brighter than the other. It can also be used to darken the blue sky background when hunting for planets like Venus or Jupiter in the daylight, making the planet strand out from the background. The filter is glass with an aluminum cell that attaches to 1.25” eyepieces and is threaded on both sides so it can be stacked with color filters.
The 94119-A 1.25” Moon filter. This is an economical Moon filter designed for smaller telescopes. Using #58 Green glass with a 25% transmission, it helps reduce the Moon’s brightness by 75% which makes it perfect for smaller telescopes (under 127mm in aperture). This filter is only threaded on one side and cannot be stacked with other filters