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More Information  · Supplied Accessories  · Recommended Accessories  · Images of Some Features Price $1,699.00 Shipping $39.95 Focal Length 400mm Focal Ratio f/10 Resolution 2.9 arc seconds Aperture 1.6" Net Weight 3 lbs. Warranty 5 years

   T-Max passband tuner

This Coronado SolarMax 40 consists of a brass and black 400mm focal length 40mm aperture f/10 refractor custom-built to optimize the performance of the Coronado Instruments SolarMax 40 Hydrogen-Alpha solar filter. The MaxScope 40 – the virtually identical predecessor of the SolarMax 40 (except in name) – got a rave review in Sky & Telescope and was named a “Hot Product" by that magazine.

The Coronado SolarMax 40 is designed to do much more for you than merely show you sunspots, as an ordinary white light solar filter can. The SolarMax 40 will reveal the ever-changing tapestry of prominences leaping off the edges of the solar disk, the explosive upheavals of flares on the face of the Sun, and the subtle mottling of granulation across the face of this nearest of stars.

The scope’s achromatic doublet lens was created for solar observing by the well-known optical designer Dick Buchroeder. It uses special multi-layer antireflection coatings on all air-glass surfaces to optimize anti-ghosting. The hard vacuum-deposited non-degenerating coatings assure a long lifetime of detailed solar observing. The scope delivers diffraction-limited performance and the extremely high contrast needed to see both subtle surface details and the full explosive power of flares and prominences.

The two-piece solar filter consists of a full-aperture 40mm etalon in front of the objective lens and a 10mm clear aperture blocking filter in the scope’s 1.25" star diagonal. The solar filter has a <0.7 Ångstrom passband, centered on the 6562.8 Ångstrom H-Alpha line. The sub-Ångstrom passband width gives you an ideal balance of prominence and surface detail alike. The filter is thermally stable, so there is no drifting off the H-Alpha line as the filter heats up during use. (Thermal stability is 0.005Å per degree Centigrade.) The 10mm clear aperture of the blocking filter portion of H-alpha system built into the star diagonal is matched to the focal length of the telescope to give full disk views of the Sun.

The SolarMax 40 has a manual 1.25" drawtube that extends for rough focusing. A helical focusing ring around the drawtube then provides the appropriate final fine focusing. This method provides enough back focus to allow both visual observing and afocal imaging. The 10mm blocking filter aperture allows you to use a Barlow in front of the SolarMax 40’s blocking filter/diagonal. This makes digital photography easier and allows the uses of a binoviewer with the SolarMax.

A T-Max bandpass tuner is installed between the solar filter etalon and the objective lens. This lets you mechanically tilt the filter’s passband off the H-Alpha line to observe Doppler-shifted solar activity. This will let you determine whether Doppler-shifted features, such as flares, are moving towards you or away from you as they leap off the surface of the Sun. For more details, click on the “T-Max" icon above.

You can use most 1.25" eyepieces with the Coronado SolarMax 40. Any good quality 50° field Plössls will work well, as their contrast is generally good and their fields are wide and flat. For optimum solar detail, however, consider adding a 12mm (33x), 18mm (22x), or 25mm (16x) Coronado CEMAX eyepiece to your system. These eyepieces use an anti-reflection multicoatings formula that has been optimized for the highest possible contrast during solar viewing of subtle prominence and surface detail. For still higher power views, consider adding the Coronado CEBAR 2x Barlow to your system. Like the CEMAX eyepieces, its performance and coatings are optimized for solar observing.

A hard carrying case is standard equipment to transport and store the SolarMax 40. A 1/4"-20 thread tripod adapter socket is built into the scope’s clamshell ring to allow mounting the lightweight (3 lb.) 16.75" long telescope on a photo tripod, as well as on most astronomical mounts. An optional Coronado Sol Ranger Sun Finder is available to make it easy to center the Sun’s image in the eyepiece. The Sol Ranger connects to the SolarMax 40’s supplied clamshell scope mounting ring.

The SolarMax 40 can be “double stacked" by adding a second SolarMax 40 filter and T-Max 40 to the front of the existing filter. Double filtering improves the scope’s already outstanding <0.7 Ångstrom resolution by cutting the bandpass to a very narrow <0.5 Ångstrom. This improves contrast on subtle disk features. A factory-matched dual etalon (40mm external etalon and 20mm internal etalon) version of the SolarMax 40, the #SM40105, provides essentially the same benefits as a “double-stacked" scope but is available at a slightly lower cost (and with somewhat higher performance) than adding a complete second 40mm filter and the appropriate adapters to the scope at a later date.