Sky-Watcher 2" Light Pollution Filter

Sky-Watcher 2" Light Pollution Filter - 20199

The Sky-Watcher 2" Light Pollution Filter is designed to significantly improve contrast when observing from suburban or urban locations. By selectively blocking common artificial light wavelengths while allowing key astronomical emissions to pass through, it helps reveal faint nebulae and subtle details that are otherwise washed out by skyglow.

Housed in a durable anodised aluminium cell, the filter simply threads into standard 2" eyepieces or accessories and is supplied in a protective storage case.

Reduce skyglow, enhance contrast

This filter is engineered to suppress the glow from mercury-vapour and other street lighting, while preserving high transmission at important astronomical wavelengths. The result is darker backgrounds and improved separation between the target and the surrounding sky.

It is particularly effective on emission nebulae, where light is emitted in narrow wavelength bands.

Optimised wavelength transmission

The Sky-Watcher Light Pollution Filter allows strong transmission of:

• Hydrogen-Alpha (H-α)

• Hydrogen-Beta (H-β)

• Doubly ionised oxygen (O-III)

This improves views of nebulae, and can give modest enhancement to galaxies, clusters and planetary detail (especially reddish features), though the effect is most dramatic on nebulae.

Ideal for smaller telescopes

While compatible with telescopes of all apertures, this filter is particularly recommended for smaller instruments up to around 114mm, where more aggressive filters may remove too much light.

Key details

• Size: 2" (threads to standard 2" eyepieces)

• Type: Contrast-enhancing light pollution filter

• Material: Optical glass in anodised aluminium cell

• MPN: 20199

The Sky-Watcher 2" Light Pollution Filter is a valuable accessory for observers dealing with light-polluted skies — helping you see more structure and contrast in nebulae and other deep-sky objects.