Variable Polarizer 2" Mounted Filter

The Optolong 2″ Variable Polarising Filter provides adjustable brightness control when observing the Moon, Venus and other bright targets. Unlike a fixed-transmission Moon filter, its two-piece polarising design allows you to change the amount of light reaching the eyepiece by rotating the upper section of the filter.

This makes it easy to use stronger attenuation when observing a bright full Moon and lighter attenuation when viewing lunar crescents or less intense targets. It can also help reduce reflections and glare during terrestrial observation.

Key features

• Adjustable brightness control by rotating the upper filter section through 360°.

• Ideal for bright targets including the Moon, Venus and daytime terrestrial subjects.

• Two-piece polarising design provides more flexibility than a fixed-transmission neutral-density or Moon filter.

• Schott B260 optical glass with a 2.0 mm substrate thickness.

• Multi-layer anti-reflection coatings applied using electron-beam evaporation and ion-assisted deposition.

• Optical quality includes fine polishing to 1/4 wave and a 60/40 surface-quality specification.

• Ultra-thin aluminium filter cell with a black-anodised finish and laser-engraved markings.

• 45 mm clear aperture to minimise obstruction within the 2″ filter cell.

• Protective storage case included with high-density EVA lining.

• Format : 2″ mounted filter for compatible threaded eyepieces and accessories.

Note: Optolong has not yet published a confirmed minimum-to-maximum transmission range for this filter.