Skip to content
IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Baader 4nm 1.25" Ultra-Narrowband OIII Filter - CMOS-Optimized (USED)
Baader 4nm 1.25" Ultra-Narrowband OIII Filter - CMOS-Optimized (USED)

Baader 4nm 1.25" Ultra-Narrowband OIII Filter - CMOS-Optimized (USED)

by Baader Planetarium
SKU BAA-2961400-125-USED
Save 16% Save 16%
$282.83
$282.83 - $282.83
$282.83
$238.37
$238.37 - $238.37
$238.37
Price Match Policy!
Only 1 left!
Qualifies for FREE Shipping on orders over $350.

In perfect condition, used

  • Baader H-alpha / O-III / S-II Ultra-Narrowband (Narrowband) 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 optical systems from f / 10 to f / 3.5
  • 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