Astronomik 6 nm OIII MaxFR Filter, 2"

Astronomik MaxFR O-III Line Filter, 6 nm FWHM

There is an ever growing demand for filters suitable for extremly fast optical systems like Celestron´s RASA or the Epsilon Astrographs made by Takahashi.

The MaxFR emission line filters are suitable up to very fast focal ratios. The Astronomik MaxFR series of narrowband-emissionline filters is perfect matched to the requirements of astronomical deep-sky imaging with fast optical systems. For the three most important emission lines of oxygen (OIII), hydrogen (H-alpha) and sulfur (SII) you may select your filters either with 12 nm or 6 nm bandwidth (FWHM).

Highest transmission:

Astronmik´s MaxFR filters are designed to work perfectly with fast optical systems. The built-in well known MFR coating technique gives you the best out-of-band blocking possible across the entire range of wavelengths from the UV up to IR! Your advantage of the design is a extremly high contrast, minimized stray light, no halos and needle-sharp stars. The Astronomik MFR narrowband emissionline filters give you the best quality of data: The best start material to be processed to a awesome final image!

♦ For 12 nm MaxFR filters this means a unlimited usability from f/1.7 to f/8 and about 85% of the maximum transmission at a f/1.4 as guaranteed.

♦ For 6 nm MaxFR filters this means a unlimited usability from f/2.2 to f/8 with about 90% of the maximum transmission at a f/2 as guaranteed performance data.

For maximum contrast the SII filter is carefully designed to block all light coming from H-alpha and NII (nitrogen).

Imaging with narrowband emissionline filters:

If you have to observe from light polluted sites (like most of us...), imaging with narrowband emissionline filters is the best way to take great images, as all kind of light pollution can be blocked very effective!

Normaly an H-alpha filter should be your first step into this amazing field of astrophotography! With an Narrowband H-alpha filter you will be able to take deep and contrasty images even wih very heavy light pollution or with the full moon high up in the sky! If you look at other astrophotos, an H-alpha is the best choice for all nebulas glowing red!

An OIII filters expands your imaging possibilities, as you are able to image all greenish/blueish structures. Planetary nebulas and star forming regions are great objects!

The SII filters completes your HSO-set of filters. With these three filters you are able to process your images like the ones from the Hubble space telescope!

The choice of the bandwidth depends on the camera and light pollution:

♦ 12 nm filters are the right choice for all DSLRs and dark-current limited cameras.
♦ 6 nm filters are the best choice for observing sites with extrem strong light pollution, cameras with low dark-current and when weak objects require the maximum contrast and star-reduction possible!

Quality aspects of the Astronomik MFR narrowband emissionline filters:

♦ MFR Coating: The 12 nm filters can be used on all instruments down to f/1.4, the 6 nm filters down to f/2.
♦ High-quality substrate: Astronomik filters are made with stress- and striae free, optically polished glass. The filter itself is made of ultra thin layers on this substrate!
♦ Parfocal filters: All Astronomik Filters are parfocal! Due to the very small thickness-tolerance the focal plane is not shifted when changing filters!
♦ Coating: Astronomik filters are made of up to 170 layers which are coated on both sides of the substrate. These layers form the filter itself and act as a anti-reflective coating.
♦ Durability: Due to the coating technique all Astronomik filters are highly scratch resistant, not sensitive to moisture and do not degrade when getting older. Every Astronomik filter will deliver it´s full perfomance and meet the specs at the point of shipping even after lot´s of years.
♦ Integated blocking: All unwanted light is blocked in the whole spectral range from UV up to the IR! (You will not need an additonal UV & IR blocker when imaging with any of the narrowband emissionline filters with coating!)
♦ Wide range of available sizes from 1,25" up to square 50 mm x 50 mm filters.
♦ Delivered in a high-quality protection & storage box.
♦ Due to the outstandding coating technique Astronomik offers a 10 year warrantee on all of their filters.

Proven quality:

All Astronomik Filters are perfect for modern cameras, including both CMOS and CCD based cameras, allowing you to capture the very best images possible with your instruments. Sharpness, contrast and the absence of any reflections is guaranteed.

Each and every Astronomik filter has to pass a complex quality control process before being suitable for delivery to the customers. Each and every emission line filter is measured with a high-end Perkin-Elmer spectral-photometer to make sure that every single filter is up to the specifications published on Astronomik´s website.

On the back of each filter-box you will find a label that details the precise sensitivity and band pass measurements for that individual filter inside the box: You will see the max transmission and the recommended range of focal ratio were the filter will give you the best performance.


You get the highest quality possible with every single Astronomik filter to be able to take perfect images with your instruments! Especialy the filters against ligh pollution and the narrowband emissionline filters will expand your imaging possibilities enormous! You are investing your money for an accessory which will work in lots of years in the same ways it did when it was brand new. Due to Astronomik´s special coating technique the filters do not degrade when getting older, and due to the MFR coating you will be able to use the filter on nearly all instruments!

♦ Line filter in protective box