Baader Planetarium Contrast Booster 2 Inch Filter

Bringing greater contrast, sharper detail and improved colour correction to an achromatic refractor is the primary purpose of the Baader Planetarium Contrast Booster. Its carefully designed spectral response reduces the bluish hue and false colour that can compromise image quality while maintaining more than 95% light transmission.

Fast achromatic refractors particularly benefit from this approach. By reducing distracting chromatic aberration, the Contrast Booster allows the underlying optical performance of the telescope to become much more apparent.

On the Moon, reduced false colour produces cleaner boundaries and noticeably sharper surface detail. Image brightness remains high and colour rendition is relatively natural, with only a slight yellowish tint rather than the strong darkening associated with traditional green contrast filters.

Planetary observation also benefits significantly, particularly on Jupiter and Mars. Surface structures become easier to distinguish while the high transmission maintains a bright image suitable for high magnification.

Terrestrial observation benefits from the same reduction of bluish haze and atmospheric stray light, helping distant subjects appear more clearly defined under conditions where atmospheric scattering would otherwise lower contrast.

A significant portion of urban skyglow and atmospheric Airglow is also suppressed. The resulting darker background increases visual separation between bright structures and the surrounding sky.

Digital imaging is another important application. Integrated UV IR blocking suppresses unfocused infrared wavelengths that can otherwise produce enlarged or poorly defined stars with digital and CMOS cameras that remain sensitive deep into the red part of the spectrum.

Spectral performance is based on a neodymium-doped glass substrate. This specialised material contributes to colour correction and contrast enhancement while sophisticated multilayer coatings precisely control the transmitted and rejected portions of the spectrum.

Optical quality is equally important. The substrate is planeoptically polished to preserve the telescope's wavefront and resolving capability. Baader specifies that the filter can be used at magnifications of 200x and above without the resolution degradation associated with simply polished filter glass.

This optical precision also allows the Contrast Booster to be positioned well ahead of the focal plane. It can therefore be used in front of a binocular viewer or in selected afocal digital imaging configurations.

A 7-layer hard multicoating is applied to the rear surface, providing a specified reflection of only 0.25%. The front surface uses a 23-layer dielectric long-pass blocker.

Both surfaces feature ion-beam hardened coatings for high mechanical durability. Coating edges are sealed to preserve long-term performance, and Baader specifies compatibility with its Optical Wonder Fluid for cleaning.

Threads on both sides allow straightforward installation in a standard optical train and also make it possible to stack the Contrast Booster with other compatible filters when required.

For solar observation, the Contrast Booster may only be used behind a suitable solar safety system. Baader specifically requires its use in combination with Baader AstroSolar Safety Film. The Contrast Booster must never be used on its own for solar observation or imaging.

Combining high transmission, sophisticated spectral filtering and high optical quality, the Baader Planetarium Contrast Booster is a versatile solution for lunar and planetary observation, digital imaging and improving the performance of achromatic refractors.

Technical specifications

• Manufacturer: Baader Planetarium
• Product: Contrast Booster
• Manufacturer SKU: 2458365
• EAN Code: 4047825009500
• Filter type: Bandpass
• Size: 2 inch
• Shape: Round
• Mounting: LPFC 6 mm cell
• Filter glass thickness without cell: 1 mm
• Net weight: 0.01 kg
• Substrate: Neodymium-doped glass
• Optical finish: Planeoptically polished
• AR coating: Phantom Coating Group
• Transmission range: Multiple bands according to spectral curve
• Transmission: Over 95%
• Rear surface: 7-layer hard multicoating
• Rear surface reflection: 0.25%
• Front surface: 23-layer dielectric long-pass blocker
• Coating hardening: Ion-beam hardened on both surfaces
• Coating edges: Sealed
• Non-ageing coating design: Yes
• High scratch resistance: Yes
• Integrated UV IR blocking: Yes
• False colour correction: Yes
• Bluish hue reduction: Yes
• Contrast enhancement: Yes
• Sharpness enhancement: Yes
• Skyglow reduction: Yes
• Atmospheric Airglow reduction: Yes
• Lunar observation: Yes
• Planetary observation: Yes
• Terrestrial observation: Yes
• Solar observation: Only with Baader AstroSolar Safety Film
• Astronomical imaging: Yes
• Digital camera compatibility: Yes
• Red-sensitive CMOS camera compatibility: Yes
• Suitable in front of binocular viewers: Yes
• Afocal imaging projection: Yes
• Suitable at 200x magnification and above: Yes
• Filter threads on both sides: Yes
• Can be stacked with other filters: Yes
• Packaging: Single filter