Coronado SolarMax III 70mm f/5.7 Double-Stacked H-alpha Solar Telescope (15mm Blocking, OTA Only)

Coronado SolarMax III 70mm f/5.7 Double-Stacked H-alpha Solar Telescope (15mm Blocking, OTA Only)

Coronado SolarMax III 70mm f/5.7 Double-Stacked H-alpha Solar Telescope (15mm Blocking, OTA Only)

B&H # COSMIIIDS15T MFR # 324006
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Product Highlights

  • Double-Stacked External H-Alpha Etalon
  • RichView and T-Max Etalon Tuning Systems
  • For Prominence and Chromosphere Viewing
  • 400mm f/5.7 Solar Viewing Refractor
  • 15mm Rear Diagonal Blocking Filter
  • <0.5Å Hydrogen-Alpha Wavelength
  • 2-Speed 2" Rack-and-Pinion Focuser
  • Vixen-Style Dovetail Mounting Plate
  • Solar Finder, 18mm 22x Eyepiece
  • Easily Convert for Nighttime Use
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Aperture: 70mm f/5.7

60mm f/6.6

Not available with current selections

70mm f/5.7 90mm f/8.8

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Coronado SolarMax III overview

  • 1Description

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
  • 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
UPC: 709942998351
In the Box
Coronado SolarMax III 70mm f/5.7 Double-Stacked H-alpha Solar Telescope (15mm Blocking, OTA Only)
  • CEMAX 18mm H-Alpha Solar Eyepiece (1.25")
  • Sol Ranger Solar Viewfinder
  • 90° 15mm H-Alpha Blocking Filter (1.25")
  • 1.25" Eyepiece Reducer Adapter
  • Cradle Ring Assembly with Dovetail
  • Hard Carrying Case
  • Limited 5-Year Warranty
  • Table of Contents
    • 1Description

    Coronado SolarMax III specs

    Optical Tube Assembly
    Aperture 70 mm / 2.8"
    Focal Length 400 mm
    Focal Ratio f/5.7
    Eyepiece Barrel Diameter 1.25", 2"
    Finderscope Yes
    Mounting System Vixen Style
    Filtration Wavelength Hydrogen-alpha
    Bandpass <0.5 Å
    Blocking Filter 15 mm (External)
    Thermal Stability 0.005 Å/C
    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 24.85 lb
    Box Dimensions (LxWxH) 31.0 x 13.7 x 13.1"

    Coronado SolarMax III reviews

    SolarMax III 70mm f/5.7 Double-Stacked H-alpha Solar Telescope (15mm Blocking, OTA Only) is rated 5.0 out of 5 by 2.
    Rated 5 out of 5 by from About Time! I have been using a double stack PST for about a year. PST suffer from smallish sweet spot of best detail. That issue is now history! Views are beautifully detailed over the entire image area. Double etalon filters give tremendous versatility of scope configuration and tuning. I was stunned. Base scope is 400mm f5.7 achromat which can be used with a standard diagonal for night celestial viewing. Install blocking filter diagonal + 1 or 2 etalons for .7A or .5A solar viewing. Image uniformity is consistent across viewing area and tunable for the features you wish to observe. Finder and vixen mount are included and great. This is a very nice solar scope well worth the cost! I prefer to view with 10mm SWA eyepiece with good eye relief. The included 18mm is nice but I like the 10mm for more detail.
    Date published: 2017-12-01
    Rated 5 out of 5 by from This is a great H-a Solar Scope I purchased the Coronado SolarMax III, double stacked instrument. It appears to be well made, all metal on the outside, feels sturdy and solid - feels massive for its size. My opinion is that it looks very cool. I have been enjoying it very much. I had also purchased the Cemax 12mm eyepiece and the 2X Barlow. My favorite view is with the 12mm eyepiece. The seeing conditions in Denver have not been the greatest due to wildfires. However, I have gotten many reasonable viewing sessions. The details of the sun, in H-a, are ever changing and each viewing looks different. That, to me, is exciting. Viewing in the narrow band light does take some getting used to. The tilt tuning controls, on the sides of the etalons work by changing the angle of the filter to the light passing through them. I have noticed that I cannot get the same tuning over the entire disk of the sun. Tuning appears different along bands that run parallel to the tuner's hinge axis. Tuning can be adjusted to bring out an area of interest though. On my instrument, the tuning axes are right angles to each other (by design I hope). At sub-angstrom bandwidths, the angle of the light from different points of the sun's disk (about 0.52 degrees in diameter) has a significant effect on tuning. I have found my time well invested in trying different setting of the tilt tuners, the "Richview" tuner and focus has allowed me to gain an understanding of what they do and how they work together. I have been able to get some extremely stunning views. Tip: While the Soll Ranger does a pretty good job of sighting in on the sun, I have found that pulling the eyepiece out of its barrel and looking into the barrel from a couple of feet away can get you right on. The trick is to center the image of the sun's disk in the window of the diagonal.
    Date published: 2018-08-08
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