Coronado's versatile SolarMax II 90 90mm f/8.8 H-alpha Double-Stacked Solar Telescope represents the largest aperture and longest focal length in the SolarMax II series. It offers the highest magnification potential and clearest views compared to smaller iterations. This scope is calibrated for the Hydrogen-alpha wavelength, and comes equipped with Coronado's RichView tuning system. This system allows direct adjustment of each of its etalon filters enabling it to be tuned up or down from the 6562.8Å wavelength for highlighting specific zones of the chromosphere and to compensate for Doppler shift that can pull prominences and other features off-band and affect views. Tuning areas of concentration back on-band allows for higher-contrast views of prominences on the solar limb.
Its primary internal etalon provides a bandpass of 0.7Å, which will reveal prominences in high-contrast. Prominences generally appear larger with this size filter than in narrower bandwidths. This version of the SolarMax II comes with a secondary etalon that fits on the front of the OTA and narrows the bandpass to 0.5 Angstroms. At this bandpass, surface contrast is improved versus wider bandpasses. This ability to change the bandpass allows users to see more areas of the Sun than with a single-etalon solar scope. Complementing the primary etalon filter is a rear internal 30mm blocking filter. This secondary filter further isolates the H-alpha wavelength to improve contrast and enhance views. While a smaller 10mm or 15mm blocking filter would suffice, Coronado includes this larger option to allow the use of eyepieces with larger field-stop diameters to be used without vignetting occurring, as might be seen with smaller filters, which would interfere with the field of view. Setting this rear blocking filter internally enables the use of the included 90° star diagonal for comfortably viewing the Sun when it is high in the sky, or without the diagonal for direct-connection of imaging rigs.
The SolarMax II is offered here without a mount or tripod, but comes with a wide clamshell mounting ring that is outfitted with a 1/4"-20 socket for attachment onto many photo/video/field tripods or on piggyback rigs, or an optional Vixen-style dovetail plate is available for use with conventional alt-az, EQ, or motorized telescope mounts.