Nebula Filter H-Beta 1.25-inch 400-600 you get to enjoy the

you get to enjoy the generous eye relief of the lower power eyepiece

This also maximizes the life of the internal coatings

while the stable Twilight I alt-azimuth mount provides smooth

taking the guesswork out of stargazing

4 focal ratio is ideal for shorter exposure astrophotography

Nebula Filter H-Beta 1.25-inch 400-600 you get to enjoy theExplore Scientific Nebula Filter 1. 25" H Beta Range from 478nm to 496nm with peak at 489nm. Transmission 94. 5% H Beta Hydrogen is the most abundant element in the universe and many nebulae glow in the light of H beta. This line filter blocks all other wavelengths (and thereby nearly all of the artificial light) and only the emission line of hydrogen beta will pass. This filter fits all standard 1. 25 inch eyepieces and filter wheels.