Baader Fringe-Killer Filter - 1.25" # FFK-1 2458370

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In Stock (8 Available)
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Our Product ID: OFIL-BP-FFK-1
Manufacturer SKU: 2458370
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Baader Fringe-Killer Filter - 1.25" # FFK-1 2458370

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  • Baader Fringe-Killer Filter - 1.25" # FFK-1 2458370
  • Baader Fringe-Killer Filter - 1.25" # FFK-1 2458370
  • Baader Fringe-Killer Filter - 1.25" # FFK-1 2458370

Quick Overview

  • Baader Fringe-Killer filter reduces violet fringing around bright objects when viewed achromatic refractors
  • Carefully designed blue and violet attenuation renders a more natural color contrast, which is even better when paired with the Baader Moon & Skyglow filter
  • Superior fine optical substrates for excellent performance, even at high magnifications
  • Hard ion-beam-deposited and scratch-resistant coating for easy, safe cleaning and long life
  • Mounted in spring-loaded optical cell to ensure superior optical performance

Product Details

Baader Fringe-Killer Filter for Achromatic Refractors

Achromat owners rejoice! Baader Planetarium’s Fringe Killer filter brings a better type of violet-fringe filtration to the amateur. Rather than simply blocking the shorter wavelengths like all other minus violet filters, the Fringe Killer carefully attenuates this specific region of the spectrum. This allows the filter to reduce the most damaging defocused blue wavelengths- with only a faint yellow color shift - without dimming and lowering image contrast by reducing the important green-yellow wavelengths, the range of spectrum where the eye is most sensitive and where refractors are their sharpest. The result is a filter that removes the majority of color fringes without affecting image brightness, imparting strong coloration, or reducing contrast. As any telescope owner knows, light is a valuable commodity for both planetary and deep sky viewing, and the fringe killer preserves every bit of light possible. Terrestrial observers will also find the qualities of this filter to be ideal for reducing chromatic aberration.

For a view with an even better color balance with noticeably boosted color contrasts, we highly recommend stacking a Baader Moon & Skyglow filter with the Fringe Killer. Stacking these filters results in an almost totally color balanced view. Image brightness is also very minimally affected due to the optimized formula of the Moon & Skyglow, along with the superb anti reflection coatings and optical quality of Baader filters.

The Fringe Killer is also a perfect compliment to the Baader Contrast Booster filter. The Contrast Booster is an aggressive filter, designed to deliver the maximum sharpness and contrast possible from an achromat. The result is complete removal of the violet haze, with a somewhat dimmer and yellowier image. The Contrast Booster also incorporates additional RGB filtration for further enhancing color contrasts. The Fringe Killer provides a milder more natural filtration that leaves fast achromats performing much like a classical f/15 achromat. The Fringe Killer delivers what we feel is an ideal combination of improved resolution, contrast and unaltered image brightness, along with a very aesthetically pleasing view.

The coatings required to accomplish this innovative filtration are exceedingly complex, requiring almost 50 layers per side, using the latest DWDM Plasma assisted coating process. The Fringe Killer has perhaps the most complex coating ever achieved on an amateur astronomical filter.

The Ideal Filter for Imaging with Achromatic Refractors

Digital Imagers with CCD, CMOS, DigiCam, and Webcam cameras will find the Fringe Killer to be the ultimate match for their achromatic refractor. The high transmission and fringe reduction work great for both planetary and deep sky imaging. Baader has also chosen to include their renowned UV/IR Cut coatings as part of the Fringe Killer formula. These coatings maintain very high transmission, with well placed sharp cutoffs in the IR and UV.

Just like all the other Baader Planetarium filters, the Fringe Killer offers their trademark high quality and features. The result is industry leading performance and value.

Superior Optical Quality, Even at High Magnification

At the heart of the Baader filters are their special fine optical substrate polishing process and advanced hard coating design. The result is a filter that imparts virtually no image degradation. Manufacturers of lesser filters, to prevent deterioration from cleaning or exposure to moisture, sometimes resort to sandwiching their delicate coatings between two layers of filter glass, resulting in potential blurred or double images. Unlike these lesser filters, the superior optical quality of Baader filters allows for use at higher magnifications which are particularly useful for studying fine detail, particularly in brighter diffuse and planetary nebulae. Baader filters can take high magnifications, and stars retain their pinpoint sharpness, even if the filter is used far ahead of the image plane when used for astrophotography or when used ahead of a star diagonal or binoviewer.  Baader filters fulfill the requirements of an ideal optical filter - to perform at highest efficiency without any other detectable effect on the image.

Advanced Optical Manufacturing for Long Life and Superior Performance

Unlike many budget filters, Baader Planetarium filters are not “biscuit cut” out of larger plates of glass, a process that causes micro-cracks around the filter edges. These cracks can attract moisture between the glass substrate and coating layers via capillary action which causes premature aging and degradation.

By contrast, each Baader filter is individually cut to size (either 1¼", 31mm, 36mm, 2", 50,4mm, 50x50mm, 65x65mm), then polished flat on both sides to a quarter wavelength to ensure maximum image sharpness and distortion over the entire filter, even when the filter is not close to the focal plane. Then each blank is then individually coated with a hard, ion-beam-deposited scratch-resistant coating. However, the coating is not applied all the way to the edge of the substrate to ensure the filter is sealed against the penetration of moisture, even in very humid conditions. This is especially important in multilayer, narrowband filters where moisture can seep in if the coating is not properly deposited. The hard coatings also mean Baader filters are easier and safer to clean without damage.

Baader filters are also tested repeatedly to comply with MIL-specifications. One common process is to boil the test specimen for one hour in salt water to induced damage. Unlike budget filters cut from larger plates, Baader filters remained completely intact without changes in their transmission characteristics after this rigorous environmental testing.

Baader’s careful engineering and manufacturing mean you need to buy a Baader filter just once and it will last you for a lifetime of astronomical observations.

About Baader Filter Cells

Many filter vendors insert their filter blanks into standard tightly-screwed filter cells. Unfortunately, the stress on the filter can result in drastic deformations of the substrate and degradation in optical performance.

That’s why all Baader filters are no longer tightly fixed but are held spring-loaded in the filter cell. The filter glass may ever so slightly “clatter” in the cell when shaken, but that neither affects the image quality nor results in a displacement in the final image. This “clatter” is not a flaw in the filter cell. It is entirely intentional.

Useful Resources

- Baader Fringe Killer Filter Data Sheet (pdf file)


Photo of fringe killer held over a sheet of paper in natural sunlight,
illustrating the high transmission and low coloration.