Astronomik UHC-E 1.25'' (M28.5)

Our 1.25" (M28.5) filters fit perfectly in all 1.25" (M28.5) filter wheels of brands like ZWO, QHY, QSI, Starlight Xpress, SBIG, Moravian, and Atik.

The orientation of the filter in the filter wheel does not matter. It does not change the optical performance.

The Astronomik UHC-E filter is our budget filter for deep-sky observation of emission nebulae and comets under light polluted skies. It’s particularly suitable for small scopes.

The UHC-E Filter increases contrast for emission nebulae and comets, blocking the light from typical streetlights and airglow. It is best suited for telescopes up to 5" / 125mm.

Main use

The Astronomik UHC-E filter provides a FWHM of 45nm and blocks the light of typical streetlights (e.g. sodium and mercury vapor) as well as airglow. This increases contrast between your target and the night sky. The contrast enhancement is less than that of the Astronomik UHC filter, but more starlight is transmitted, making it better suited for smaller telescopes. Since the UHC-E filter passes a spectral line of Carbon (due to the higher FWHM), it opens up the possibility of comet observation.

Other uses

• Observation of Jupiter’s clouds.
• Easier resolution of Double Stars.
• Photography under light-polluted skies with DSLRs and other cameras.

Alternatives

If you use a telescope with an aperture larger than 5", we suggest using our standard UHC-filter because of its greater contrast enhancement capabilities. If you use a telescope larger than 8", you can try our OIII filter for even better results when observing specific nebulae.

Suitability

• Visual observation (dark skies): Reasonable, UHC filter is more suitable
• Visual observation (urban skies): Good, for telescopes up to 125mm aperture and medium exit pupil
• Film photography: Good, but very long exposure times
• CCD photography: Good, when used with an additional IR-block filter
• DSLR photography (original): Good, color balance is near perfect
• DSLR photography (astro modified): Good, color balance is near perfect
• DSLR photography (MC modified): Good, when used with an additional IR-block filter
• Webcam / Video (Planets): Unsuitable
• Webcam / Video (Deep Sky): Very good, if light pollution is a big problem

Technical Data

• Typical 94% transmission at 486nm (H-beta)
• Typical 95% transmission at 496nm (OIII)
• Typical 95% transmission at 501nm (OIII)
• Typical 94% transmission at 656nm (H-alpha)
• Transmission from 465nm to 530nm and above 645nm
• Full width at half maximum: 45nm
• Parfocal with other Astronomik filters
• Glass thickness: 1mm
• Completely resistant against high humidity, scratches, and aging effects
• Diffraction limited: The filter will not reduce the optical performance of your telescope!
• Astronomik filters are delivered in a high-quality, long-lasting filter box
• Since 2008, we ship filters with a completely new design. Any kind of halo or strange reflection is a thing of the past