Features:

• The 1.25" Neutral Density Moon filter reduces glare so you can see more lunar detail and surface features with your telescope

• Metal filter cell threads directly into the 1.25 inch barrel of your telescope eyepiece

• Useful for different caliber astronomical telescopes through which the light of the Moon can be extremely overwhelming

• Perfectly neutral color will not alter the natural color of the Moon

Specifications:

• Brand: SVBONY

• Model: SV139

• Type: Neutral Density Filter 

• Material: Optical glass lens, Aluminum Frame

• Barrel diameter: 1.25''

• Optical density value: 1.2

• Thread: Standard M28.5*0.6mm

• Net Weight of Set: 20g

Universal Science:

• Waxing Crescent Moon - As the Moon moves around the Earth, we get to see more and more of the illuminated half, and we say the Moon is waxing. At first we get a sliver of it, which grows as days go by. This phase is called the crescent moon. It's very good effectto use the ND4 filter at this time

• Last Quarter Moon - Three weeks after new, we again can see half of the illuminated part. This is usually called last quarter. Quarter Moon - A week after the new moon, when the Moon has completed about a quarter of its turn around the Earth, we can see half of the illuminated part; that is, a quarter of the Moon. This is the first quarter phase. It's very good effect to use the ND8 filter In this two time period

• Gibbous Moon - From now on, until it becomes new again, the illuminated part of the Moon that we can see decreases, and we say it's waning. The first week after full, it is called waning gibbous. It's very good effect to use the ND16 filter at this time

• Full Moon - Two weeks after the new moon, the moon is now halfway through its revolution, and now the illuminated half coincides with the one facing the Earth, so that we can see a full disk: we have a full moon. It's very good effect to use the ND1000 filter at this time