Baader Clear Filter (Optically Polished) 2"

Article number: FC-2
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♦ Baader LRGBC Filters ♦

 Simply put - Baader's new LRGBC anti-reflection filters deliver improved color separation and image quality without annoying halos. Unfortunately, their obvious improvements will likely cause many astro-imagers to re-take images of their favorite objects...

What makes the Baader filters so unique?  Through an extensive coating stack design and testing program, Baader has partnered with the world's leading thin film coating company to produce transmission curves that border on the ideal.  Their ultra steep cutoffs and high transmission (>95%) allowed Baader to do something to a degree no other RGB filter set can manage - they are able to effectively separate the important H-Beta and O-III lines.  The Baader Blue filter passes virtually all of the H-Beta and O-III lines, while the Green filter is able to capture all of the O-III line, without encroaching into the H-Beta line.  None of the light is wasted by either filter.  In this way, O-III is represented as it should be, a teal (blue-green) color, and H-Beta is captured solely in the blue. Never before has this degree of separation been achieved, and with such high transmission of both lines. 

In addition, the Green and Red filter passbands nearly touch, leaving only a sharp notch to block out the primary Mercury/Sodium light pollution line at 580nm.  The high transmission everywhere else delivers the shortest combined exposures possible with every detector.

In addition to their special transmission properties, the Baader coatings were developed from the outset with another key goal in mind - eliminate the annoying reflections present in other astro-filters.  To achieve this freedom from reflections required careful balancing of the coating stacks and further extensive testing.  The result can be seen in these two images, showing the freedom from reflections in the L and C Filters (click on the image for a larger version).  Image courtesy of Mr. Johannes Schedler.

The high optical quality of the Baader narrowband filters guarantees no loss in sharpness or contrast.  Each substrate is fine-optically polished plane parallel to deliver a smooth and accurate 1/4 wavefront over the entire surface.  Each filter is blocked and polished individually, not cut out of a larger plate of glass.  The special custom polishing operation sets Baader filters apart from the lower optical quality provided by standard commercially precision polished filter substrates used by most other filter manufacturers. 

Coatings are professionally applied in Germany by the most sophisticated equipment available today, ensuring high consistency for bandpass cutoffs, transmission, and out of band blocking.  The anti-reflection coatings are evenly balanced on both sides of the filters to reduce surface stresses and prevent deformation of the substrates. The ultra-hard ionbeam deposition ensures the coatings will never degrade from use or normal cleaning.   Unlike many competitive filters, Baader coats each filter individually.  Baader filters remain sealed at their coating edges for a long life without degradation (you can see evidence of this process by inspecting for a thin un-coated region at the very edge of the filter).  Though more costly, this process avoids the coating failures that can result when filters are simply 'biscuit cut' from bulk coated sheet glass, leaving ragged coating edges for moisture to penetrate and cause coatings to peel away from the glass.  Baader filters are intended for a lifetime of real-world use.


For more information on the unique performance and features of these filters,

please click the following link:

Baader LRGBC Anti-Reflection Filter Data Sheet (182 kB)



Noted astro-imager, Johannes Schedler (Panther Observatory), found the Baader filters to be superb at capturing colors as well as freedom from reflections.


"I am more than satisfied with the performance of the new Baader filter set. The absence of any reflections from bright stars makes clean-up procedures obsolete for many objects displaying foreground stars. The simple 1:1:1 RGB weighting together with a distinct color separation supplies deep star colors and fine details in galaxies and nebulas."

(Rosette image taken with TEC-140, 10 minutes per color, courtesy of Mr. Johannes Schedler, Panther Observatory).



Please click on the thumbnails below for some other  images taken by Mr. Schedler through the Baader LRGBC filters. 




NGC 3372 - Eta Carina

NGC 5128 - Centaurus A

M20 - Trifid Nebula



Baader LRGB filter sets and C-filters are available in four sizes, standard mounted 1¼", 2", as well as 50.8mm diameter round and 50mm Square bare substrates (unmounted) for use in larger format cameras.   Clear filters for focusing and full-throughput are also available.


NOTE for Users of the Unmounted Filters (RND and SQ):  The preferred oriention of the filter is to have the highest reflectivity side facing skyward. 







Red Spectrogram

(transmission of solar spectrum)

Green Spectrogram

(transmission of solar spectrum)

Blue Spectrogram

(transmission of solar spectrum)

RGB Combined Spectrogram

(transmission of solar spectrum)


Filter Sets (set of 4 filters, filters not sold individually)

- Baader LRGB Filter Set, 1.25"   (#FLRGB-1)

- Baader LRGB Filter Set, 2"   (#FLRGB-2)

- Baader LRGB Filter Set, 31mm Round (2mmThick)  (#FLRGB-RD31) NEW!

- Baader LRGB Filter Set, 36mm Round (2mmThick)  (#FLRGB-RD36)

- Baader LRGB Filter Set, 50.4mm Round (3mmThick)  (#FLRGB-RD50)

- Baader LRGB Filter Set, 50mm Square (3mm Thick)   (#FLRGB-SQ50)

- Baader LRGB Filter Set, 65mm Square (3mm Thick)   (#FLRGB-SQ65)


Clear Focusing Filters

- Baader Clear Filter, 1.25"   (#FC-1)

- Baader Clear Filter, 2"   (#FC-2)

- Baader Clear Filter, 31mm Round (2mmThick)   (#FC-RD31)  NEW!

- Baader Clear Filter, 36mm Round (2mmThick)   (#FC-RD36)

- Baader Clear Filter, 50.4mm Round (3mmThick)   (#FC-RD50) 

- Baader Clear Filter, 50mm Square (3mm Thick)   (#FC-SQ50) 

- Baader Clear Filter, 65mm Square (3mm Thick)   (#FC-SQ65)

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