Redesigned with external dual 60mm solar etalon filters and an upgraded 2-speed 2″ rack-and-pinion focuser, Coronado’s SolarMax III 70mm f/5.7 Double-Stacked H-alpha Solar Telescope builds on the success of their earlier iterations to provide users with a compact yet capable solar viewing optic. With the primary etalons now positioned externally, users can simply and easily remove the front solar and rear blocking filters to convert the SolarMax III into a competent nighttime viewing telescope – greatly increasing the scope’s versatility.
Specifically calibrated to isolate the hydrogen-alpha wavelength with a less than 0.5Å bandpass, the SM3’s two etalons reduce the bandpass to refine the observation experience to see prominences in high-contrast against the black backdrop of space while revealing surface granulation and texture that broader bandpasses are unable to resolve. Each etalon has an independent tuning system that gives users the ability to precisely and easily bring them on-band to improve contrast and enhance views when atmospheric interference or Doppler-shift cause the optical system to come off-band. The primary etalon comes equipped with Coronado’s rotating RichView tuning system, while the T-max tilt-tuner is employed on the secondary etalon. These two tuning methods ensure that interference between the two light paths is minimized, to further improve views.
The SolarMax III gets an updated focusing system, versus the earlier iteration, with a 2″ 10:1 dual-speed rack-and-pinion system from the previous 1.25″ helical one. When used as a conventional scope, larger 2″ conventional eyepieces and accessories can be used, or the more common 1.25″ size with the addition of the included 1.25″ reducer adapter. The more precise focuser is complemented by a rear 90° 15mm blocking filter to provide a wider field of view and allows for full-disk viewing even with higher magnification eyepieces. This secondary blocking filter is used to further isolate the H-alpha wavelength for improved contrast on surface granulation, and prominence detail. A larger blocking filter also enables the use of eyepieces with greater field-stop diameters to be used without vignetting occurring, as might occur with smaller-aperture blocking filters.
To get users started, Coronado includes a 2″-to-1.25″ reducer adapter and an 18mm 1.25″ CEMAX eyepiece that produces a 22x power. The eyepiece holder and blocking filter will accept any 2″ solar eyepiece or accessory, and with the reducer adapter any 1.25″ eyepiece can also be used — further increasing the scope’s versatility. The optical tube assembly is offered here without a mount or tripod, but comes with a Vixen-style dovetail plate for users who already have a reliable and stable mount and support system. To protect the OTA and accessories during transport and storage, Coronado includes a hard carrying case with custom-cut foam lining, that is color-matched to the OTA in their elegant Black and Gold color scheme.
Optical Tube Assembly
Use for daytime solar observation; or, with the solar and blocking filters removed, as a conventional nighttime scope
70mm aperture
f/5.7 focal ratio
400mm focal length
Achromatic refractor-style lens configuration
Fully multi-coated optics improve light transmission, color rendition, contrast, and sharpness
10:1 dual speed rack-and-pinion focuser allows for fast coarse and precise fine focusing to achieve tack-sharp images
2″ drawtube enables the use of larger eyepieces and accessories for full-disk viewing without vignetting
Solar Filter
Double-stacked 60mm aperture solar filter system reduces the bandpass for improved contrast and views
Fully external filters, etalons, and tuning systems allow filter to be completely removed
Tuned for viewing in the hydrogen-alpha wavelength, at 6562.8Å with a bandpass if less than 0.5Å
Reveals prominences in high contrast against the black backdrop of space
Observe surface granulation and texture with high-contrast
Rear 1.25″ 15mm diagonal secondary blocking filter improves contrast, and shows more space around the sun to allow for higher magnification-eyepieces to be used while maintaining full solar-disk viewing
Proprietary RichView tuning system on the primary etalon, and the T-max tilt tuner on the secondary, allow the etalons to be independently tuned for Doppler-shift compensation or to highlight specific zones without having the two tuned light-paths interfere with each other
Thermal stability: 0.005Å/°C
Mounting
Optical tube assembly only — mount and tripod required for proper use
Mounting ring assembly allows the relative position of the OTA to the mount to be adjusted for proper balance and limit obstruction
Vixen-style dovetail plate available for use with conventional telescope mounts
Weight: 9.3 pounds
Included Accessories
CEMAX eyepiece:
1.25″ diameter barrel
18mm focal length yields 22x
52° field of view
Fold-down rubber eyecup for use with or without eyewear
Designed specifically for use at H-alpha wavelengths to improve contrast and minimize glare
Long and comfortable 20mm eye relief
Sol Ranger viewfinder:
Solar finder enables safe aiming of the OTA at the sun
Carrying case:
Protects OTA and accessories during transport and storage
Hard aluminum exterior with reinforced corners and edges
Dual snap-lock latches with hinged handle
Custom-cut interior foam lining
Optical Tube Assembly
Optical Design Achromatic Refractor
Aperture 70 mm / 2.8″
Focal Length 400 mm
Focal Ratio f/5.7
Focuser Dual-Speed Rack-and-Pinion
Eyepiece Barrel Diameter 1.25″, 2″
Finderscope Yes
Mounting Vixen Style
Filtration
Filtration Wavelength Hydrogen-alpha
Bandpass <0.5 Å
Blocking Filter 15 mm (External)
Thermal Stability 0.005 Å/°C
General
Batteries None
GPS No
Wi-Fi No
Assembled Dimensions 19.3 x 5.9 x 5.5" / 49.0 x 15.0 x 14.0 cm
Weight 9.3 lb / 4.2 kg
Packaging Info
Package Weight 22 lb
Box Dimensions (LxWxH) 31 x 13.7 x 13.1"
