Used Baader H-alpha 2" f/2 Ultra-Highspeed CMOS Optimized 3.5nm Filter


  • Sale
  • $324.95
  • Regular price $499.00

Yes, our inventory is accurate!

Qualifies for Free Ground Economy Shipping (CONUS Only)

Not Returnable Please note that used items are not returnable.


This is a Baader H-alpha 2" filter in excellent condition.  The optics and body are clean.  It comes in its original jewel case.  




Baader has designed this 2" H-alpha ultra-highspeed filter to be precision-grade and provide astrophotographers an excellent complement to their imaging setup. With 3.5 nm FWHM, this ultra-highspeed filter from Baader is recommended for extremely fast optical systems from f/3.4 to f/1.8, like the Celestron RASA astrographs. The filters are designed to allow for 1:1:1 exposures. This matches the typical CMOS quantum efficiency and s/n ratio. The filters are optimized for CMOS cameras, but they work great with CCD cameras as well.

H-alpha filters are highly favored when it comes to narrowband filters and are deep red in color. Hydrogen is the most common element in the universe and is present in emission nebula such as the North American and the Pelican, planetary nebula such as the Dumbbell and Ring, Wolf-Rayet objects like Crescent and Thor's Helmet, even supernova remnants like the Veil nebula.

This Baader Planetarium H-alpha (Ha) f/2 ultra-highspeed filter is CMOS optimized with Life-Coat. This coating is a hard coating that will not peel, flake, and will not physically degrade even in the most extreme weather conditions. This coating is also designed to withstand repeated cleaning with fine optical cleaning equipment. This coating is so durable that Baader is confident it will last the life of the filter.

Not only do the filters have sealed coating edges with the Life-Coat, but they are also hard coated with Reflex-Blocker and planoptically polished. All of the edges are blackened for increased contrast and eliminate any reflection that would come from light falling on the edge of the filter. The filters are also equipped with a filter-lead-side-indicator in the form of a frontside outer rim.

Baader Ultra-Highspeed 2" CMOS Optimized Filter Features

  • Transmission Ranges: H-alpha
  • Filter Thickness (w/out glass) 2 mm
  • Half Bandwidth: 3.5 nm
  • Central Wavelenth: 656.3 nm
  • AR-Coating: Reflex Blocker hard coated and planoptically polished
  • Filter Size: 2"
  • Threaded: Yes
  • Usage: CMOS, CCD, H-alpha
  • Mounted: Yes
  • Filter Type: Narrowband
  • FIlter Shape: Round
  • Feature Highlight: CMOS-Optimized with Life-Coat


SKU Number
Model Number
Single Filter, Set, or Accessory
Single Filter
Filter Type
Filter Size
50.8mm (2")
Filter Shape
Filter Insert Style
Baader Model Number

Filter Wavelength (Center or Range)
565.3 nm
Filter Bandwidth/Bandpass
3.5 nm
Filter Optical Thickness
2 mm