The filter's application spans aperture ratios from 1:3 to 1:15, suitable for a wide range of telescopes and lenses. Compared to filters from other manufacturers, the Astronomik UHC filter excels in revealing more stars and finer details in celestial objects, maintaining the sharpness and optical quality expected from high-performance lenses.

The filter works by blocking emission lines from high- and low-pressure sodium (Na)- and mercury (Hg)-vapor lamps and all lines of natural airglow, while allowing H-beta and OIII lines to pass through. This selective transmission enhances the contrast between the sky background and observed objects.

Additionally, the Astronomik UHC filter is recommended for photography of Jupiter's clouds and offers improved separation of double stars. 

In summary, the Astronomik UHC filter is indispensable for astronomers seeking to maximize visual clarity and contrast in deep-sky photography, making it an essential tool for all deep-sky photographers alike.

Other uses

The 1.25" and 2" socket models can be used for visual observation.

Alternatives

• The Astronomik UHC-E filter is more suitable for photographing comets or when there is less light pollution.
• We recommend the Astronomik CLS or CLS CCD filter for photographing galaxies and the milky way in moderate light pollution. The Astronomik CLS CCD filter has an additional integrated infrared(IR)-blocking layer.

Suitability of the Astronomik UHC filters

• CMOS and CCD photography: Good for emission nebulae, requires an additional Astronomik IR-Block filter
• DSLR photography (original): Good for emission nebulae, color balance is shifted but contrast is enhanced
• DSLR photography (astro-modified): Very good for emission nebulae, color balance is also good
• DSLR photography (MC-modified): Very good for emission nebulae, requires an additional Astronomik IR-Block filter

Technical data

• Typical transmission of 95% at 486nm (H-beta)
• Typical transmission of 95% at 496nm and 501nm (OIII)
• Typical transmission of 95% at 656nm (H alpha)
• Transmission range: 480nm to 505nm and above 645nm 
• Full-Width-Half Maximum (FWHM): 25nm
• Glass thickness: 1mm (except Astronomik OWB Type 3 and XT filters)
• Finely polished optical glass, free of any striae, residual stresses, and bubbles
• Extremely scratch-resistant and durable coating
• Completely resistant against high humidity and aging effects
• Astronomik MFR coating (Astronomik Deep-Sky RGB, UV-IR Block L-1, L-2, L-3, and Narrowband-Emissionline filters)
• Parfocal with other Astronomik filters
• Diffraction-limited
• Optimized spectral windows
• Delivered in a high-quality, long-lasting filter box

Due to the high-precision machining of the carrier substrate, all Astronomik filters are parfocal with wedge errors far below all common tolerances. Astronomik filters are diffraction-limited, ensuring that the optical performance (resolution and contrast) of your telescope is not compromised. Issues concerning focal distances and the exact alignment of images from each color channel are therefore effectively eliminated. 

All Astronomik filters are ideal for modern cameras, including both CMOS- and CCD-based models, ensuring you capture the best possible images with your equipment. Sharpness, contrast, and the absence of any reflections and halos are guaranteed. Even with bright stars in the field of view, nebulae and galaxies will be captured with the finest structures. The Astronomik MFR coating is designed for optimal performance across a wide range of focal ratios of the optics used.

Every Astronomik filter undergoes a rigorous quality control process before delivery. Additionally, each Astronomik Narrowband-Emissionline filter is measured using a high-end PerkinElmer Spectrophotometer to ensure it meets the specifications published on our website. On the back of each Narrowband-Emissionline filter box, you will find a label detailing the precise spectral data for that specific filter, including the maximum transmission and the recommended range of focal ratios.