Coronado SolarMax III 90 Double Stack 3.5" F/8.9 solar telescope with 15mm blocking filter


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This 90mm Coronado SolarMax III 90 DS RichView tuning solar telescope has dual etalons for both <0.5 and <0.7 Ångstrom passband H-Alpha solar observing and binoviewing.
Our Product #: SM39015DS
Coronado Product #: 324012

Product Description

This Coronado SolarMax III 90 dual-etalon solar telescope is designed to do much more for you than merely show you sunspots, as an ordinary white light solar filter can. Its dual passband Hydrogen-Alpha solar filter reveals features of the Sun that are normally hidden by the fierce glare of this nearest of stars - features that change constantly as you watch. The high resolution 90mm aperture of the SolarMax III 90 reveals small, intricate, and subtle details in the ever-changing tapestry of prominences leaping off the edges of the solar disk, the explosive upheavals of flares on the Sun's disk, and the subtle mottling of granulation across the face of the Sun.

The Coronado SolarMax III 90 DS Hydrogen-Alpha solar telescope by Meade is "double-stacked," with two filter etalons for increased contrast of solar disk features. The two "true" external etalons use Coronado's unique RichView tuning system. The removable second etalon threads onto the front of the scope to give you the best views possible. Since both etalon filters are now external to the telescope, you can easily remove both filters and rear blocking filter diagonal to use the scope as a normal refractor for night time astronomy. It’s like having two scopes in one!

Double-stacking the etalons improves the scope's already outstanding resolution and contrast by cutting the single etalon model's narrow <0.7 Ångstrom passband to a very narrow <0.5 Ångstrom. Narrowing the passband improves the contrast and visibility of subtle disk features, although it slightly reduces the brightness of prominences. For maximum prominence brightness, the front etalon of the SolarMax III 90 DS can be removed to let the scope function as a single etalon solar scope providing a <0.7 Ångstrom passband. The 30mm clear aperture blocking filter is designed for binoviewing and imaging with large 35mm-format chip size DSLR and CCD cameras in both single and double etalon configurations.

The Coronado SolarMax III 90 solar telescope by Meade starts with a brass and black 800mm focal length 90mm aperture f/8.8 refractor. It has been custom-built to provide high definition Hydrogen-Alpha solar feature views using Coronado's unique RichView tuning Hydrogen-Alpha solar filter.

The dual-etalon "double-stacked" solar filter has a <0.5 Ångstrom passband, centered on the 6562.8 Ångstrom H-Alpha line. The very narrow passband width gives you higher contrast on disk details than a single etalon system, with only a slight reduction in prominence brightness. The filters are thermally stable, so there is no drifting off the H-Alpha line as the filters heat up during extended use.

The 15mm blocking filter version of this scope is designed for visual observers as well as imagers who do not need quite as wide an illuminated field for use with medium (APS-C) chip size DSLR or CCD cameras.

The new and revolutionary RichView tuning assembly of the Meade Coronado SolarMax III 90 represents a breakthrough in solar observing. This patented system allows very precise direct tuning of the primary filter etalon to shift the filter's passband off the H-Alpha line. This lets you observe Doppler-shifted solar activity to 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. No other commercially available H-Alpha telescope can provide the tuning range and accuracy of the SolarMax III 90. Now you can tune for the highest contrast views of active regions, flares, filaments, and other surface detail, or quickly and easily re-tune for prominences on the solar limb.

The SolarMax III 90 has a dual speed 2" focuser allowing a precise focus for all your solar needs.  This method provides enough back focus to allow both visual observing and imaging.

A set of Coronado Cemax 1.25" eyepiece is standard equipment, providing magnifications of 32x with a 1.62° field, 44x with a 1.18° field, and 67x with a 0.78° field. You can use most 1.25" eyepieces with the Coronado SolarMax III 90, as well. Any good quality 50° field Plössls will work well, as their contrast is generally good and their fields are wide and flat. For still higher power views,  the standard Coronado Cemax 2x Barlow will round out the eyepiece set. 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 90mm Coronado SolarMax III. A mounting ring is provided to let you mount the 33" long 26 lb. SolarMax III 90 telescope on a suitably-sturdy astronomical mount with a Vixen saddle. The supplied Coronado Sol Ranger Sun Finder makes it easy to center the Sun's image in the eyepiece. The Sol Ranger connects to the supplied SolarMax III 90 scope mounting ring as can be seen in the image above.

Tech Details

Aperture 3.54"
Binary and Star Cluster Observation No
Focal Length 800mm
Focal Ratio f/8.8
Galaxy and Nebula Observation No
Lunar Observation No
Weight 26 lbs.
Planetary Observation No
Resolution 1.29 arc seconds
Warranty 5 years


Review by:
Had a chance to view through a Solar Max and the Sun's detail is spine-tingling. Detail resolves precisely. I have never viewed our local star in such high quality splendor. Great way to spend daylight, awaiting the night sky! Wow! (Posted on 8/2/2019)
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Supplied Accessories

  • 90mm f/8.8 optical tube, dual etalon <0.5 and <0.7 Ångstrom SolarMax II Hydrogen-Alpha solar filter, combined 30mm aperture BF30 blocking filter and 1.25" star diagonal, Cemax 1.25" eyepiece set, lens cover, clamshell mounting ring, Sol Ranger finder, hard case.