The Ostara O-III filter is a more specialised nebula filter compared to some other types. It is specifically for Planetary nebula such as M57, Dumbell and the Eskimo nebula , plus diffuse nebula such as the Swan and Veil. From my personal experience I have had my best ever view of the Eskimo nebula where it jumped out at me from the back ground sky.
Be aware, this filter is suitable for good quality telescopes over 4″. You will not be able to get the full potential using a small starter telescope. For small telescopes, the Ostara Moon / Skyglow filter will aid reduce the background glow.
Available in 1.25″ and 2″, the Ostara O-III filter comes in a sturdy foam lined case. Image shows the wavelength chart
Click HERE to purchase from Northern Optics