Baader AstroSolar Filter for Binoculars & Camera Lenses - 70mm Filter Aperture # ASBF-70

ASBF – Baader Solar Filters for Binoculars and Camera Lenses

Baader's ASBF line of solar filters permit safe visual observation with all types of binoculars or safe solar photography with all camera lenses. The ASBF filters are similar to the ASSF line of filters (for spotting scopes) except that the mounting cell is flat or cut on one side (see photos). This allows you to:

• Use two filters in close proximity to each other on the two objectives of binoculars even for small inter-pupillary (IPD) distances
• Rest a filter mounted on a camera lens on a flat surface without stressing the filter cell or the film, or
• Mount a filter onto a finder close to the main telescope tube.

ASBF-70 Solar Filter Specifications

• Item number: ASBF-70 or 2459327
• AstroSolar film aperture: 70mm (2.75")
• Outside diameter clamping range (with included 13mm bolts): 75 - 90mm (2.95 - 3.54")
• Inside diameter clamping range (with included 13mm bolts): 101 - 116mm (3.97 - 4.56"). See additional info below.
• Suited for aperture range: 60 - 80mm (2.36 - 3.14")
• Outside diameter of filter cell: 130mm (5.11")
• Weight: 2.6oz / 73g

Additional Filter Details and Features

• Made of original Baader AstroSolar Safety Visual Film (ND 5.0), cell mounted, and quality inspected by skilled members of Baader's staff.
• The AstroSolar filter material is mounted onto a plastic ring where the plastic ring itself works as stabilizing element for the filter cell. This still plastic ring is mounted onto the aluminum front frame. The thermal expansion coefficient of the plastic and the film are similar.
• Clear white IR-rejecting front ring with reinforcing raised edges along the outer and inner circumference, designed to protect the solar filter material from contact with any sharp metal edge.
• Includes 3 injection molded centering-bolts with threaded brass inserts to center the filter-cell in front of the tube opening (13mm diameter; 24mm length). This fastening system keeps the filter snugly in place and centers the filter. Each bolt features injection molded rubber grip-faces, shaped to easily slide onto any telescope tube but hard to come off.
• No tool mounting and adjustment of the centering bolts to fit a wide variety of mechanical tube diameters. Bolts are made to contact the outside of the optical instrument tube for most applications.
• For some optical items (such as refractor and Newtonian reflector telescopes), you may be able to attach the bolts on the inside of the instrument tube. However, this requires a clear depth of about 20mm on the inside for adequate engagement of the centering bolts which many instruments (like binoculars, camera lenses, and SCT/Mak-Cass telescopes) do not have.
• Includes non-rotating sliding fasteners made from aluminum that hold the centering bolts.
• Additional Phillips screws are integrated into the sliding fasteners so that the centering bolts can be firmly fastened with a screw driver if preferred by the user.
• Index scale provided beside each adjustment slot - adjacent to each sliding fastener - for fast and repeatable adjustment of the filter cell onto different telescope tubes.
• Black sliding washers supplied to securely cover the full length of the adjustment slots in the aluminum frame – for blocking sunlight from passing trough the filter cell beside the filter area.
• Three security straps included to secure the position of the filter cell with Velcro-adhesive pads. A safety feature to absolutely ensure a secure fit in front of the telescope under virtually all circumstances.
• Securely packed in a cardboard box with stiff cardboard inlay for safely shipping the filter; Instruction booklet included.

About Baader AstroSolar Film and Solar Filters

The world's finest objective solar filter material - Baader Planetarium's AstroSolar Safety Film - is now available in a complete range of high-quality mounted Baader Solar Filters. Their innovative design and construction enables each filter to fit a wide range of instruments - from high end telescopes, to spotting scopes, camera lenses, and even special versions to fit binoculars. Each filter is precisely mounted at Baader onto special cells, guaranteeing a stress-free mounting that preserves the full optical quality of the AstroSolar film.

Baader Solar Filters provide a professional and secure solution to observe and image the Sun using AstroSolar Safety Film. Many ready-made filters stretch the filter material like a drumhead in order to make it look like a piece of glass. However, this absolutely destroys the image quality, rendering the film useless for high magnification work. AstroSolar is mounted entirely stress free onto Baader's filters in order to perform like a high precision plane-optical window. Even though it may seem counterintuitive, Baader AstroSolar film must show slight ripples! When the film is put under stress by an improper cell mount, its optical quality is degraded and it performs just like a common coated glass-filter made of untreated float glass.

In its September 2000 issue, Sky & Telescope magazine proclaimed Baader Planetarium's AstroSolar Safety Film to be "the new standard in solar filters." AstroSolar Safety Film delivers white light views of the Sun that are unmatched by any other objective solar filter or material. The views through AstroSolar display fine solar details, including fine penumbral detail, solar granulation, and lighter colored faculae. The disk is set against a dark background, free of the haze and scatter that is common in typical 'mylar' films or inexpensive glass filters. The performance of Astro Solar Filter Film is even more remarkable when considering its very low cost.

What is even more important - with AstroSolar Film the Sun appears in its real color - neutral white (with only a slight bluish tinge). Other films and glass filters produce a blurry bluish or reddish/orange/yellow Solar image, thereby cutting part of the spectrum. Especially with an orange sun, it is very hard to see faculae regions which are visible predominantly in the blue portion of the spectrum.

Due to its neutral color balance, AstroSolar Film enables the use of various color (or interference) filters which allows the observer to concentrate on certain spectral passbands for investigations of different layers within the solar "atmosphere". It is also possible to further improve the stability and sharpness of the solar image through the use of the Baader Solar Continuum Filter (sold separately). Views of granulation and faculae are particularly enhanced through the use of this continuum filter, in combination with AstroSolar film.

Please note that you cannot see solar prominences with white light solar filters such as this - that requires the use of sophisticated and significantly more expensive narrowband solar filters or telescopes. Solar filters made with AstroSolar Film with a neutral density (ND) of 5.0 can be used for visual and photographic, imaging and video applications.