Baader ASTF 140 AstroSolar ClearWhite ND 5.1 (OD=5.1) 140 mm solar filter (Baader Planetarium, SKU: 2423013) is a front-aperture filter designed for safe visual observation and white-light solar photography. Its 140 mm clear aperture allows photospheric details to be seen, including sunspots and the structures surrounding them, also during observations at high magnifications.

Key features

• AstroSolar® ClearWhite Safety Film with an optical density of OD 5.1
• reduces the intensity of sunlight approximately 125,000 times
• neutral, bright white image of the Sun without a pronounced blue or orange tint
• high image sharpness and contrast, suitable for observations at high magnifications
• double-sided metallized filter material mounted without tension
• temperature-compensated cell limiting the effect of temperature changes on the optical properties of the filter
• adjustable centering pins enabling installation inside or outside the telescope tube or dew shield
• safety straps protecting the filter against accidental slipping
• complies with the transmission requirements specified in the EN ISO 12312-2:2015 standard

Included components

• Baader ASTF 140 AstroSolar ClearWhite OD 5.1 solar filter
• 3 centering pins with a diameter of 10 mm and a length of 38 mm
• 3 centering pins with a diameter of 20 mm and a length of 38 mm
• 3 safety straps with self-adhesive mounts
• 3 rubber caps for unused holes
• instruction manual

Technical specifications

• catalogue number: 2423013
• type: front-aperture filter for solar observation
• filter material: AstroSolar® ClearWhite Safety Film
• optical density: OD 5.1
• light transmission: 0.0008%
• clear filter aperture: 140 mm
• recommended instrument aperture range: 130–150 mm
• outer cell diameter: 230 mm
• mounting range inside the tube with 10 mm pins: 190–220 mm
• mounting range inside the tube with 20 mm pins: 200–230 mm
• mounting range outside the tube with 10 mm pins: 170–200 mm
• mounting range outside the tube with 20 mm pins: 160–190 mm
• centering pin length: 38 mm
• weight: 200 g
• application: visual observation and astrophotography
• observed object: Sun

The Baader ASTF 140 provides stable mounting and a neutral image of the Sun, enabling detailed visual observations and photospheric imaging.