SVBONY 2″ UHC Light Pollution Filter

Product Overview

This is the 2″ version of the SVBONY UHC (Ultra High Contrast) light pollution filter. A UHC filter has a narrower passband than a broadband CLS filter: it reduces light from mercury-vapour and sodium-vapour street lamps and the natural oxygen airglow of the atmosphere while passing the emission lines of nebulae. The sky background turns darker and emission and planetary nebulae gain contrast. SVBONY builds it with an optical glass element in an aluminium frame and supplies it in a transparent storage case.

Who It's For

This is a good match if you observe or image emission nebulae from urban or suburban skies with a 2″ diagonal, 2″ eyepieces or a 2″ imaging train, and want the background darkened more than a broadband filter would manage.

Key Features & Design

• Ultra-high contrast passband: selectively reduces artificial-light wavelengths so emission nebulae stand out.
• Darker background: SVBONY rates the background darker and nebula contrast higher than with typical broadband filters.
• Optical glass in an aluminium frame: built for frequent use.
• 2″ format: for low-power, wide-field eyepieces and larger imaging sensors where a 1.25″ filter would vignette.

Recommended Uses

• Wide-field visual observing of emission nebulae: the Veil, North America and Orion nebulae through 2″ low-power eyepieces.
• Planetary nebulae: improved contrast on the Ring, Dumbbell and Helix.
• Colour imaging under bright skies: emission targets through a 2″ nosepiece or filter drawer.

Compatibility and Accessory Notes

• Fit: threads into the filter thread of 2″ eyepieces, diagonals, nosepieces and filter drawers.
• 1.25″ trains: SVBONY makes the same filter in 1.25″ (F9131A), which we also list.
• UHC vs CLS: the UHC suits brighter skies; SVBONY's CLS is the wider-band option for moderately dark sites.

Good to Know Before You Order

• Best on emission objects: galaxies and star clusters are broadband targets and gain little from a UHC filter.
• Dimmer stars and colour shift: the narrower passband dims stars visually and gives images a colour cast that is corrected in processing.
• Weight: SVBONY does not publish a weight for this filter.

Frequently Asked Questions

Is it difficult to set up?

No. It threads by hand into the filter thread of a 2″ eyepiece, diagonal or nosepiece.

Is it for visual use or imaging?

Both. SVBONY presents it for visual observing and astrophotography.

Should I choose 2″ or 1.25″?

Choose 2″ if you use 2″ eyepieces or a 2″ diagonal, or image with a sensor large enough that a 1.25″ filter would vignette.

Bottom Line

In short: a 2″ UHC filter that darkens light-polluted skies and lifts emission and planetary nebulae, for wide-field visual observing and 2″ imaging trains.