Astronomik 2″ OIII Filter

Astronomik OIII 2″ filter

If you are looking for a filter that will truly transform the way you see the universe, the Astronomik OIII 2″ filter is exactly what you need. Designed for astronomers who want to get the most out of their telescope - whether for visual observation or astrophotography - this filter ranks among the most popular emission filters in the world. Its reputation among both amateur and professional astronomers speaks for itself.

How the OIII filter works

OIII filters transmit only a very narrow band of wavelengths corresponding to the emission lines of doubly ionized oxygen - specifically around 496 nm and 501 nm. These are precisely the wavelengths at which planetary nebulae, supernova remnants and large emission nebulae such as the Veil Nebula or the Crescent Nebula shine most brightly.

At the same time, the filter effectively blocks the rest of the spectrum, including unwanted glow caused by:

• urban light pollution
• sodium and mercury vapour street lights
• natural sky background glow (airglow)

The result is a dramatically increased contrast between the observed object and the background - even under conditions that would otherwise make visual observation of these objects impossible.

Build quality and optics

Astronomik pays exceptional attention to the quality of their filters. The body of the Astronomik OIII 2″ filter is machined from lightweight and durable aluminium, ensuring a precise fit in a standard 2″ telescope focuser or camera adapter. The optical glass features a multi-layer anti-reflection coating that minimises reflections and light loss at the filter surfaces - which is especially important during visual observation, where every photon counts. Thanks to precise manufacturing, there is no distortion of star shapes or degradation of sharpness, so the filter will not compromise the performance of your optics.

Visual observation and astrophotography

The Astronomik OIII light pollution suppression filter is equally suitable for direct visual observation and for imaging. For visual use, you will particularly appreciate the contrast of nebulae - objects such as M27 (Dumbbell Nebula) or M57 (Ring Nebula) stand out even under a light-polluted suburban sky.

For astrophotography, the filter works excellently with both monochrome and colour cameras and is indispensable when creating narrowband images in the Hubble Palette style (SHO). The standard 2″ thread allows easy installation into a filter wheel or direct use in the focuser.

Made in Germany - decades of expertise

Astronomik filters are manufactured in Germany with a strong emphasis on the highest optical precision and long-term parameter stability. The German manufacturer has decades of experience developing filters specifically for astronomical applications, which is reflected in:

• precise control of transmission curves
• long-term coating stability
• mechanical durability of the entire product

Astronomik filters are chosen by beginners taking their first serious step forward as well as by experienced astrophotographers with years of practice. If you are looking for a filter that will last for years and keep revealing new details in the night sky, the Astronomik OIII 2″ is a choice you will not regret.

Key specifications