Compared to the CMOS-optimized Baader (Ultra) Narrowband filters, the 20 nm H-alpha filter lets much more light through. This makes the stars in the image brighter, allowing easier focusing, and the filter can be used at all focal ratios: There is no need for pre-shift as with narrowband filters.
This filter is especially interesting for users of color cameras (which are less red-sensitive than monochrome cameras) who do not need extreme narrow-band filters and want to enrich their color images with H-alpha. At the same time, this filter is a valid alternative to a standard R filter of the RGB scheme. It blocks much more of the deteriorating light pollution and still passes all H-alpha for all focal ratios.
A notable difference to all H-alpha pass filters on the market is the fact that this filter includes highly efficient UV/IR blocking, being completely blocked down to 1400 nm, to eliminate blur ("thermal noise") caused by unfocused light in refracting optics.
The Baader H-alpha Bandpass filter (20 nm) has all the advantages of the new generation of CMOS-optimized Baader filters:
Higher contrast, tailored to typical CMOS quantum efficiency and s/n ratio.
Reflex-Blocker™ coatings, for the highest absence of halos, even in the most adverse conditions of auxiliary optics.
Filter thickness identical to existing standards, with maximum care for parfocality.
All-around blackened edges, with filter entrance side indicator in the form of a black outer edge on the telescope side, to additionally eliminate any reflections due to light hitting the edge of a filter, making additional front masks unnecessary.
Each filter is individually coated, with the coating edge sealed (NOT cut out of a larger plate with coatings left exposed, read more).
Life-Coat™: increasingly tougher coatings to enable a coating that will not age for life, even in the harshest environment.
Baader H-alpha Bandpass 1¼" filter with 1¼" (M28.5mm) filter thread
H-alpha filter with 20 nm FWHM (CWL 656.3 nm), therefore excellently suited for night visual - and photographic use with CCD and CMOS cameras on telescopes with all f-ratios. Attention: this filter alone is not suitable for direct observation of the sun!
With new highly effective UV/IR blocking coating from 300 nm to 1400 nm.
Similar to the O III Super G filter, the 20 nm H-alpha filter is an excellent high contrast deep sky H-alpha/red filter for RGB applications, optimized for all color CCD and CMOS chips. It enables high-contrast imaging of H-II regions (e.g., North American nebulae) even from light-polluted environments.
Hard-coated and polished plano-optical Front-Reflex-Blocker™ - with sealed coating edges (Life-Coat™).
Features:
NET WEIGHT (KG): 0.06
TRANSMISSION RANGE: H-alpha
FILTER THICKNESS (WITHOUT CELL): 2 mm
HBW (HALF-BANDWIDTH): 20 nm
CWL (CENTER WAVELENGTH): 656.3 nm
AR-COATING: dielectric coating, plano-optical polishing
FILTER SIZE: 1.25 inch
FILTER USAGE: CMOS, CCD, H-alpha, IR-Cut
FILTER MOUNTING: Mounted (LPFC 6mm)
FILTER TYPE: Narrow Band
SINGLE OR SET? Single filter
FILTER SHAPE: round
