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Baader 3.5 / 4nm f/2 Ultra-Highspeed Filters – CMOS-optimized (H-alpha / O-III / S-II)

SKU FCHALHSU-1 (Baader #2961375)
Original price $289.00 - Original price $1,879.00
Original price
$289.00 - $1,879.00
Current price $324.00
Filter Usage: H-alpha (3.5nm)
Filter Size: 1 25 inch

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Baader has released a whitepaper guiding you how to select the best filter for your telescope system, and why this is important in relation to "PRESHIFT" to stay "on band". Read More

Baader has released the New CMOS-Optimized filters. Please contact us for further info. Be sure to read more in our blog at 

Now with 47.4 mm unmounted for use with FCCT

  • Baader H-alpha / O-III / S-II f / 2 Ultra-Highspeed Filter Set - Premium Grade
  • 3.5 / 4 nm half width (to harmonize the exposure time of H-alpha with O-III / S-II), recommended for extremely fast optical systems from f / 3.4 to f / 1.8
  • Specially designed for the special filter requirements when used with highly opened optics such as the Celestron RASA astrograph
  • Enables the highest contrast even with the strongest light pollution, minimizes the size of the stars, makes the finest nebula details accessible - indispensable under Bortle 9/8/7 / (6) sky
  • Reflex-Blocker ™ hard-coated and optically polished - with sealed coating edges ( Life-Coat ™ )
  • Blackened edges all around, with a filter front indicator in the form of a black outer edge on the front
  • Optimized for modern CMOS cameras, but ideally suited for CCD camera technologies

The new generation of Baader CMOS-optimized filters features:

  • CMOS-Optimized Baader Filter
  • Increased contrast
  • Ever more narrow passbands
  • Reflex-Blocker™ coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics
  • FWHM on each filter category carefully designed to allow for 1:1:1 exposures, matched for typical CMOS quantum efficiency and s/n ratio
  • Identical filter thickness to existing standards, with utmost care for parfocality
  • Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
  • Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed read more)
  • Life-Coat™: evermore hard coatings to enable a non-aging coating for life – even in a most adverse environment

Limited-Lifetime-Warranty for CMOS-optimized Baader filters

A Baader Planetarium exclusive. Filters incorporating Baader Planetarium’s Life-Coat™ technology are so durable that Baader Planetarium warrants the coatings for the life of the filter. Baader Planetarium has developed Life-Coat™ using materials and processes that result in coatings which will not degrade or fail for a lifetime. Life-Coat™ coatings resist moisture, temperature extremes, and are hardened to withstand normal cleanings.

Baader Planetarium guarantees their Life-Coat™ coatings will not peel, flake or physically degrade and will withstand repeated cleaning with fine optical cleaning equipment. The Limited Lifetime Warranty applies to the original purchaser and does not cover failure from mis-use, physical damage through improper handling, or improper cleaning.

MANUFACTURER Baader Planetarium

2 mm Thickness = 1.25"/ 2" / 31mm / 36mm

3mm Thickness = 50.4mm / 50x50 / 65x65

HBW (HALFBANDWIDTH) 3.5 nm (H-alpha) / 4 nm (O-III / S-II)
CWL (CENTRAL WAVELENGTH) 656,3 nm / 500,7 nm / 671,7 nm
AR-COATING Reflex-Blocker™ hard coated, planeoptically polished
SPECIAL FEATURES CMOS-optimized with Life-Coat™
FILTER MOUNTED Mounted (LPFC 6mm) / Unmounted 
TYPE OF FILTER f/2 Ultra-Highspeed
SINGLE OR SET? Singles and Filter-Set
FILTER SHAPE round / square (depending on size)

Whitepaper addressing filter selection and PRESHIFT