Coronado SolarMax III - 90 mm H-alpha solar telescope with BF30 block filter

Coronado SolarMax III H-Alpha Solar Telescope with 90 mm aperture and BF30 block filter

With the compact SolarMax III telescopes, observing the sun in H-Alpha is a great pleasure! The integrated True Etalon filter provides higher contrast and sharper imaging than other solar telescopes with smaller filters.

The SolarMax III telescopes have an improved focuser with reduction and other high quality features. Since the filters can be removed from the Solarmax III, the solar telescope can also be used as an achromat for nighttime observation.

In the wavelength range of 656 nanometers - called H-alpha - the sun shows a constantly active surface and prominences at the solar limb. In H-alpha light, there is always something to see on the Sun!

RichView™- & T-Max-Tuning

The H-Alpha filter is a so-called etalon. In the etalon, destructive interference of the incident light cancels out most of the radiation in the visible spectral range and allows only certain frequencies to pass.

Because the wavelength of H-alpha light varies minimally with ambient conditions, the etalon filter must be set precisely and readjusted as necessary during observation. Point the telescope at the Sun and focus on the edge of the Sun with the focuser. Rotate the large ring gear of the RichView™ system until the structures on the Sun are visible in maximum contrast. Then use the small T-Max tuning wheel to slightly tilt the tilt of the etalon to achieve maximum image brightness.

Double Stack

Every SolarMax telescope is also available with Double Stack. This means that two etalon filters are installed one behind the other. This reduces the full width at half maximum of the transmitted light of the H-alpha line to less than 0.5 Ångström. Without the double stack, the half-width is less than 0.7 Ångström. In the product name and the technical data of the telescopes the full width at half maximum is given.

The smaller full width at half maximum is noticeable as higher contrast. The structures on the sun appear three-dimensional. However, the image is also darker and finer adjustments must be made with the tuning system because of the smaller full width at half maximum of the filter.

Blocking Filter

The diagonal with the eyepiece receptacle houses the blocking filter. This filter blocks out of the wavelengths transmitted by the etalon all except H-alpha and is therefore a very important component of the overall solar telescope system, which must not be removed!

The number after the abbreviation BF in the product name indicates the diameter of the block filter in millimeters. For example BF30 means that the block filter has a diameter of 30 millimeters. For purely visual observation, a small block filter is sufficient; for photography, a larger one should be chosen.

Sol Ranger

Adjusting the sun in the telescope can be more difficult than you think and often leads to involuntary gazing at the sun with an unprotected eye! The Sol Ranger finder scope is a special sun finder with a ground glass screen. This allows you to align your telescope easily, safely and quickly.

Three Cemax eyepieces are included in the scope of delivery. The eyepieces of this series are specially optimized for H-alpha observation. The optimization applies to the coating. The eyepieces have no filter effect and can therefore also be used at night.