Coronado SolarMax III 70 mm H-Alpha Solar Telescope Double Stack with BF15 Blocking Filter

Coronado SolarMax III H-Alpha Solar Telescope 0.5 Ångström with Blocking Filter BF15

Observing the sun in H-alpha is pure joy with the compact SolarMax III telescopes. The integrated „True“ Etalon Filter provides more contrast and a sharper image than other solar telescopes with smaller filters.

The SolarMax III telescopes have an improved dual-speed focuser and further high-quality features. As the filters can be removed from the Solarmax III, the solar telescope can also be used as an achromat for night viewing.

In the wavelength range around 656 nanometres (called H-alpha), the sun shows a permanently active surface and prominences at the limb. There is always something to see in H-alpha light!

Double Stack:

Two etalon filters are installed in a row. By this, full width at half maximum of the transmitted light of the H-alpha line is reduced to less than 0.5 Ångström.

The smaller half width manifests as higher contrast. The structures on the surface seem three-dimensional, but the image is also darker and has to be finely readjusted with the tuning system, due to the narrower half width of the filter.

RichView™- & T-Max-Tuning

The H-alpha filter is a so-called etalon. In the etalon, most of the radiation in the visible spectral range is cancelled by destructive interference of the incident light. Only the wanted wavelength around 656 nanometres passes through.

To achieve this, the effective width of the etalon has the be set exactly and to be readjusted during the observation. Point the telescope to the sun and focus the sun´s limb with the focuser. Turn the big adjustment ring of the RichView system until the structures on the sun are visible with maximum contrast. Then you can tilt the etalon slightly via the small max-tuning wheel until maximum image brightness is achieved.

Blocking Filter BF

The deflection optics with the eyepiece receptacle houses the blocking filter. This filter reduces the brightness of the sun´s image and therefore is an important part of the overall system "solar telescope" which must not be removed!

The number after the abbreviation BF in the item name specifies the diameter of the blocking filter in millimetres. BF15 for example means that the blocking filter has 15 millimetres diameter. The BF15 is optimal for photography, because structures close to the sun (prominences) can also be displayed.

Sol Ranger:

Pointing the telescope at the sun is more cumbersome than you think and often a reason for involuntary glances to the sun with the unprotected eye! The finder scope Sol Ranger is a special solar finder with ground glass. With this, you can point your telescope easily, safely and quickly.

Included in the scope of delivery is a Cemax eyepiece The eyepieces of this series are particularly optimized for observing in H-alpha. The optimization applies to the coating. The eyepieces have no filter effect and therefore can be used at night, too.