2007-06-04 07:02:20 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
These filters block most of the light except for a narrow band around certain nebula emission lines. This makes nebulae radiating at those wavelengths stand out more distinctly, because eveything else appears much dimmer. The OIII filter is particularly good for planetary nebulae. It will make dim planetaries visible, and is also often used to "blink" a starfield. When you pass the filter in front of the eyepiece, stars will be greatly dimmed but tiny planetary nebulae will stay bright.
Other narrowband nebula filters select oxygen and hydrogen lines and work welll on the Veil Nebula among other objects.
2007-06-04 10:47:23 · answer #1 · answered by injanier 7 · 0⤊ 0⤋
they narrow the bandwidth of light that can enter your eye or camera, etc, through the lens giving you a sharper view of the object at hand without all the other 'light-pollution' obscuring things.
2007-06-04 14:07:31 · answer #2 · answered by johnjohnwuzhere 3 · 1⤊ 0⤋