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Solar Observation > Solar telescopes > Coronado > SolarMax III > Coronado ST 70/400 SolarMax III BF10 <0.5Å Double Stack OTA
Product no.: 59506

ST 70/400 SolarMax III BF10 <0.5Å Double Stack OTA

$ 4,910.00 incl. VAT, plus shipping costs
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Express shipment possible for delivery the day after tomorrow, 09.06.2023!

Product description

More about the series SolarMax III...

Observing the sun in H-Alpha is a lot of fun using these compact SolarMax III telescopes! The integrated ‘True’ Etalon filter provides higher contrast and a sharper image than other solar telescopes with smaller filters.

SolarMax III telescopes have an improved focuser with sensitive focusing and other high-quality features. The filters can be removed from the Solarmax III, allowing the solar telescope to also be used as an achromat for observing the night sky.

The sun is observed at a wavelength of 656 nanometers - known as H-alpha - showing an ever active solar surface and prominences at the sun's edge. There is always something to see on the sun in the H-alpha!!

RichView™ tuning: The Doppler effect causes the wavelengths of interesting structures to vary around the H-alpha line of 656.3 nanometers. This effect is particularly noticeable in the change between the central solar disk and the edge (prominences). The RichView™ tuning system allows you to adjust the filter, to find the best possible contrast.

Please note: The aperture mentioned in the product name refers to the apochromat's front lens. You can find the size of the etalon filter in the technical data.

Double stack: Every SolarMax telescope also comes with double stack. This means that two etalon filters are fitted one behind the other. This reduces the half width of the light which passes through the H-alpha line to less than 0.5 Angstroms. Without double stack, the half width is less than 0.7 Angstroms. The half width is provided in the product name and in the telescope's technical information.

The smaller half width results in higher contrast. The Sun’s structures appear three-dimensional. The image is also darker and needs to be finely readjusted using the tuning system due to the filter’s smaller half width.

BF blocking filter: The deflection optics with the eyepiece receiver also accommodate the blocking filter. This filter reduces the brightness of the solar image and is therefore a very important part of the solar telescope, and which must under no circumstances be removed! For purely visual observing, a small blocking filter is sufficient, but for photography a larger one should be selected.

Sol Ranger: Pointing a telescope at the sun is more difficult than you may think and can often involve involuntary glimpses of the sun with unprotected eyes! The Sol Ranger finder scope is a special solar finder that uses a ground glass screen. This allows you to point your telescope at the sun easily, safely and quickly.

Delivery includes a Cemax eyepiece. The eyepieces of this series are specially optimized for observation in H-alpha. The optimization applies to the remuneration. The eyepieces have no 'filtering effect' and can therefore also be used at night.

It is not only important which telescope you buy, but also where you buy it.

We provide extra help:

  • We are a leading telescope dealer and know these instruments like the back of our hands.
  • We are always very happy to offer our assistance after your purchase, should you encounter any problems with your telescope’s setup or operation.
  • Our ‘Telescope Basics’ booklet - an 80-page beginner's guide for our telescopes – is provided free of charge with every telescope we sell.



Type of build
Solar H-Alpha
Aperture (mm)
Focal length (mm)
Aperture ratio (f/)
Resolving capacity
Limit value (mag)
Light gathering capacity
Max. useful magnification
Tube weight (kg)
etalon filters (mm)
Blocking Filter (mm)
< 0,5
Double Stack
Filter systems
Tube construction
Full tube


Connection ( to eyepiece)
Type of build
Gear rack
Free aperture (mm)
Gear reduction
1:10 Fine movement
Connecting threaded socket (camera-side)
Adjustment range (mm)


Type of build
Mounting type
no mount

Included accessories

Prism rail
Tube clamps
Finder scope
Solar finder
1.25'' eyepieces
Transport cases
Deviating optics


SolarMax III

Area of application

yes (H-alpha)

Recommended for


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*All prices include VAT plus shipping costs.

Coronado ST 70/400 SolarMax III BF10 <0.5Å Double Stack OTA
Coronado ST 70/400 SolarMax III BF10 <0.5Å Double Stack OTA

Transport cases

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