Solar Accessories

Baader Solar Products

Kendrick Solar Products

Baader Cool-Ceramic Safety Herschel Prism (BPHERP) - for Refractors Only (see caution note below)

We are pleased to announce that we offer Baader Planetarium’s 2" Cool-Ceramic Safety Herschel Prism. This Herschel prism affords the finest detail possible in solar viewing.  The contrast and sharpness that it provides when observing surface detail will leave you breathless. No solar filter can compare! Additionally, it reveals the sun in a true white-light, uncolored by filters.

A Herschel prism is a unique prism that is angled at 23 degrees. It passes 95.4% of the sun’s light and heat through the prism and out the back side. The 4.6% of the light that is directed to the eyepiece requires the use of a 3.0 neutral density filter. This filter must always be used when visually observing and, therefore, is permanently installed.


This new generation Herschel Prism incorporates some unique features that add to its safety and ease of use. A layered, perforated-metal heat cage traps the excess energy transmitted through the prism, rendering it harmless. What little light and heat that remains is finally absorbed by a translucent ceramic tile. This translucent tile displays the image of the sun, serving as a solar finder. Simply move your telescope about until you see the sun appear on the translucent tile and you are all set. It is much quicker and more accurate than watching the scope's shadow on the ground.

We are offering the “photographic version" of the Baader Herschel Prism. This version comes complete with a full compliment of 2" neutral density filters (ND-1.8, ND-0.9, ND-0.6 and permanently mounted ND-3.0) and a 2" Solar Continuum filter. The Solar Continuum filter helps to further boost contrast, revealing sunspot and surface granularity detail (it does have a green colorization). A foam-lined metal carry case is provided for convenience and protection. The Baader Herschel Prism is compatible with Baader's Astro T-2 System. Please follow this link to view a copy of the User Manual.

Note: Baader lists the light path distance as being 114 mm measured from the nosepiece flange (not the insertion depth) to the top flange of the eyepiece holder. The position of eyepiece optical centers will reduce this spacing by 5 to 10 mm since the eyepiece will sit down into the eyepiece holder. When using the Herschel Prism for imaging, the eyepiece holder can be replaced with the Baader 2" to 42 mm adapter (BP27) so that a camera can be directly attached using a camera T-ring. This configuration will have a spacing distance of 67 mm flange to flange, plus the T-ring and camera. Please see the above link to the Baader manual for more information.

A question that is always asked is, "Does it damage my telescope to have it looking at the sun for long periods of time?" No! The lens passes the infrared (heat) part of the spectrum as efficiently as the visible part of the spectrum. Since the lens does not absorb or retain the infrared light, it does not heat up.

CAUTION - Important Limitation of Use: It is important to know that a Herschel Prism can only be used with refracting telescopes. It can not be used on any style reflecting telescope. If you own a Petzval-style refractor, or any design which puts elements to the rear of the scope where excessive heat build-up can occur, it is best to check with the manufacturer regarding their specific scope. [Note that Al Nagler of TeleVue has stated that the rear elements of the TeleVue Petzval scopes are sufficiently forward that no damage will occur to their scopes.] Regarding visual use, Baader has tested the prism for safety in refractors up to 8" apertures. They do note that you will want to add an additional neutral density filter for viewing comfort with the larger scopes.

CAUTION - Secondary optics, such as flatteners, telecompressors, barlows, and filters need to be placed after the Herschel Prism, not in front of it.

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AstroSolar™ Filter Material from Baader Planetarium

The Quest for High-Quality, White-Light, Solar Filters

For years our customers have asked us to recommend a solar filter that would not degrade the image of our fine refractors. Years ago, aluminized Mylar material was sold in very thin sheets, and was quite good for high-resolution visual and photographic work. However, the material had several drawbacks - it was metallized on only one side and so was prone to multiple pinholes. It required 2 sheets back to back which allowed rubbing of the surfaces in windy conditions causing degradation of the metallization. The film had a grain structure and produced a strong cross pattern of a pinhole test source (it was not diffraction-limited). This produced a hazy bluish, low contrast final image, although sunspot detail was quite good. In the following years, the original thin aluminized Mylar was discontinued to be replaced by a thicker double-coated film that did not have the sharpness of the original. On top of that, the contrast was even more degraded.

Along came inexpensive commercial glass solar filters made from plate glass. We tested a number of these and found them to have extremely poor optical figure and thus could not recommend them to any of our customers. This situation has not changed to this day.

Technical Specifications

Enter the new BAADER AstroSolar™ safety film. This new high-strength polymer is unlike anything else sold today. Thomas Baader tested hundreds of films on a double-pass autocollimator before discovering this special material that produces a high contrast, scatter-free diffraction-limited image. To produce this special film, the manufacturer uses a patented high-temperature process, similar to annealing, to eliminate internal strains.The material is then ion implanted and metallized with a tough, color-neutral layer on both sides of the film. This ion implantation/metallization process (also patented), produces a high-contrast film that stands up to considerable abuse, unlike the metallized mylar materials used in virtually every other commercial solar filter today. The coating cannot easily be rubbed off, and in that respect is actually safer than coated glass filters. As mentioned above, the material is coated on both sides. Even if you find a pinhole on one side, it is likely that the other side is still coated, providing the protection of that single layer. Since it is nearly impossible for any manufacturer to produce filter coating that is absolutely pinhole-free, a few pinholes may be found.

Unlike commercial film and glass filters, Baader's AstroSolar™ will not significantly degrade the imaging capabilities of your telescope. Roland Christen of Astro-Physics has checked out samples of this material on a double-pass interferometer and measured a 94% Strehl Ratio when placed flat over a 6" test optic. Compare this to Strehl ratios of 45% for aluminized Mylar and less than 24% for inexpensive glass solar filters.


Theory is fine, but what will this new material show you? We asked two prominent solar observers, Wally Piorkowski and Gordon Garcia to test the material and give us their opinion. Both observers used high quality Apo refractors in their evaluations. Gordon was indeed impressed by the resolution and contrast, and actively spread the word to all his solar colleagues. When Wally and I tested the filter at Astro-Physics, he noted the pleasing, almost neutral color on the surface, and the black background sky due to the lack of scatter and few, if any, pinholes. We could see extensive solar granulation all over the surface, as in any high-resolution glass filter. Sunspots showed detail deep within the umbra and the penumbral brushes were so finely resolved, they looked like eyelashes. But what surprised Wally most was that he could see for the first time white filamentary faculae all over the sun's surface, not just at the edge.

You can use this filter material with any normal size amateur scope (I would not suggest its use for the Keck telescopes). However, to improve optical performance during the turbulent conditions often experienced due to hot daytime air, it may be best to use a smaller off-axis aperture to improve detail (see the instructions for making a filter).

Additional Considerations

You may also wish to add the Baader Solar Continuum Filter to your Solar observing arsenal. This filter, when combined with the AstroSolar Filter Material gives increased contrast for finer detail in surface features.

Order Information

Each order will come with these instructions: "Making an Inexpensive Filter Cell for BAADER AstroSolar™ Material" and "Care and Safety Instructions."

BAADER AstroSolar™ Density 5 - Visual, A4 size, 200 x 290mm (7.9" x 11.4")

BAADER AstroSolar™ Density 5 - Visual, 1/2 Meter size, 500 x 1000mm (19.7" x 39.4")

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Kendrick Sun Finder (KSF6000)

The Kendrick Sun Finder makes locating the sun and centering it in your eyepiece a cinch…no more trying to line up the shadow of the scope on the ground.  It will work with all your solar accessories and dedicated solar scopes. 

The Sun Finder projects a solar dot onto the white target which can be viewed either from the front of the finder or through the cut out on the back.  The finder comes with a double sided adhesive foam tape for easy adhesion to a solar filter ring or other surface.

Put one on each of your solar filters!

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Solar Continuum Filter - 1.25" (BPSC125) and 2" (BPSC2)

Unsurpassed contrast of photospheric details is achieved by an extremely narrow half bandwidth of only 8nm. Functions like a monochrometer, suppressing the effects of atmospheric turbulence to provide images that appear markedly more stable.

Focus "Sweet Spot Generator" - completely eliminates the usual focusing guesswork - the image snaps to a razor sharp focus at the exact focal position. Image the sun the way professionals do!

IMPORTANT: The Solar Continuum Filter MUST be used in conjunction with a visual density white-light solar filter or Herschel Prism (with ND3.0 filter) in front of the lens. We suggest Astro-Solar ND 5.0 Visual Filter material, also from Baader Planetarium. DO NOT attempt to use this filter without a white-light filter in front of your main telescope optics. Serious damage to your eyes could result.

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Kendrick Solar Filters Using Baader AstroSolar™ Filter Material

If you would rather not make your solar filter, you may prefer to purchase a ready-made filter. Kendrick Astro Instruments anticipated this need and has an economical solution!

Using the Baader AstroSolar™ material, Kendrick manufactures aluminum filter cells in a variety of apertures. With three long nylon screws placed on tabs at 120° intervals, this filter cell enables you to safely attach the filter to your lens cell or dew shield for a variety of telescope apertures.

Please use the following chart to determine which is the proper filter for your telescope.

AP Telescope or Binoculars Dew Shield O.D.

Visual Filter Part #

Fits Tube
PB105X70, PB15X70 (need 2) 87mm KS6002 85mm to 95mm
90EDFL, 92F7EDF (1999-2002) 107mm KS6004-A 98mm to 108mm
92mm f/6.65 Stowaway 112mm KS6004-B 107mm to 115mm
105EDFS, 105EDT


117mm to 130mm
Star12ED 137mm KS6007 130mm to 140mm
130EDFGT, 130GTX
155mm KS6008-B 150mm to 160mm
130EDFS, 130EDT, STAR130ED
164mm KS6009 157mm to 167mm
140EDF27, 140EDF4
184mm KS6011 182mm to 192mm
155EDF, 155EDFS, 155EDT
189mm KS6011 182mm to 192mm
194mm KS6011-A 191mm to 201mm
175EDF, 180EDF, 180EDT
226mm KS6013 223mm to 233mm
lens cell KS6012-A 214mm to 224mm

Additional Considerations

You may also wish to add the Baader Solar Continuum Filter to your Solar observing arsenal. This filter, when combined with the Kendrick Solar Filters gives increased contrast for finer detail in surface features.

Those who want the photograhic density filter material might also consider purchasing the Baader Neutral Density Filter. The neutral density filter performs double duty, turning your Kendrick Photographic Filter into a safe visual filter system, and then also acting as a primo moon filter to avoid the eye burn that can come from moon observation through medium to large aperture instruments.

Please click here for Kendrick Solar Filter pricing.

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This page was last modified: November 2, 2018

Astro-Physics, Inc.
11250 Forest Hills Road, Machesney Park, IL  61115, U.S.A.
Phone: 815-282-1513   Fax: 815-282-9847