Baader Filters H-alpha/OIII/SII CMOS Narrowband 2" (70896)

H-alpha Filter:
The H-alpha filter allows light with a wavelength of 656nm to pass through. It is considered the best option for narrowband H-alpha astrophotography when aiming for high-contrast images and revealing intricate nebula details, even in areas affected by strong light pollution.

OIII Filter:
The narrowband O-III 3nm filter is specifically designed for observing nebulae. It allows a narrow 3nm bandwidth of light centered at a wavelength of 500nm, which matches the OIII emission lines, while blocking all other wavelengths.

SII Filter:
The narrowband S-II 7nm filter transmits light at a wavelength of 672nm with a 3nm bandpass, making it ideal for nebula photography.

Suitability:
These filters are suitable for capturing most emission nebulae, planetary nebulae, and supernova remnants.

Achieving the Hubble Look:
If you want your astrophotography to resemble images from the Hubble Space Telescope, such as the “Pillars of Creation” in the Eagle Nebula (Messier 16), consider adding the SII (sulfur) filter after the H-alpha and OIII filters. Like the H-alpha filter, the SII filter is a deep red filter close to 672nm. Using H-alpha, OIII, and SII filters together allows for tri-color narrowband imaging that produces the signature “Hubble look” for many emission nebulae. This technique can also be used even when the moon is up, so your equipment remains in use throughout the month.

Line Filter Details:
A line filter with a 6.5 nanometre half-width is recommended for optical systems with focal ratios from f/10 to f/3.5.

Baader’s CMOS-Optimised Filters Feature:

• Increased contrast

• Narrower half-widths (FWHM)

• Reflex Blocker™ coatings, which greatly reduce sensitivity to reflections from nearby optical accessories, even under difficult conditions

• FWHM specifically engineered for each filter category, enabling balanced 1:1:1 exposures tailored to typical CMOS sensor efficiency and signal-to-noise ratio

• Identical filter thickness compared to existing standards, with precise attention to ensure all filters remain parfocal

• Blackened edges and a filter front indicator in the form of a black outer edge, which helps prevent any reflections from stray light hitting the filter edge

• Each filter is precision-polished, individually coated, and sealed at the coating edge (not cut from larger plates with exposed coating edges)

• Life-Coat™ technology, providing extra-durable coatings for a lifetime of use, even in the harshest environments

Purpose:
This new generation of CMOS-optimized filters is designed to set a new standard for amateur astronomy.

Specifications:

• Central wavelength (nm): 656.3, 500.7, 671.7

• Half-value width (nm): 6.5

• Frame: 2-inch

• Mount material: Aluminum

• Optical coating: Reflex-Blocker™

• Telescope connection: 2-inch

• Suitable focal ratios: f/10 to f/3.5

• Filter thickness (mm): 2

General Information:

• Type: Filter

• Construction: Line filter

• Series: Narrowband

Areas of Application:

• Suitable for astrophotography

• Not intended for visual observation

• Not suitable for observing double stars

• Not recommended for the Moon or planets

• Ideal for nebulae and galaxies