Coronado SolarMax II 40 H-Alpha Filter with BF15

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  • Regular price $2,099.00
  • $1,299.00
  • You save: $800.00 (38%)

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Coronado SolarMax II 40 H-Alpha Filter with BF15

The Coronado SolarMax II 40 H-Alpha Filter with BF15 offers an incredible opportunity for the amateur to enter the world of H-Alpha observing at a relatively low price. This particular SolarMax (other sizes are available) is a 40mm AS1-series, thermally-stable H-Alpha filter with a wavelength of 6562.8A and a bandwidth of <0.7A. It is ideal for use with a short, fast refractor and is mounted to the front of the telescope with a Coronado Instruments adapter plate, which is sold separately.

The Coronado SolarMax series filters come in two parts, the front narrowband element as listed above and a secondary interference filter which mounts at the eyepiece end of the telescope. You cannot use the individual units separately. The blocking filter you should use depends on the focal length of your telescope and a BF15 is included with this filter. The BF15 is a blocking filter that is mounted inside the body of a 1-1/4" right-angle diagonal. It is optimized to provide a full disc image on telescopes with a focal length of up to 1500mm.

Note: If you have a telescope with a focal length of more than 1500mm, you will need a different blocking filter (BF30 for up to 3000mm), or a different SolarMax (60 or 90mm) with a BF30 for scopes between 1500mm and 3000mm. Or, if you have a scope with a focal length of 1000mm or less, you can buy the SolarMax 40 with the BF10 and save a little money. Call or check elsewhere on this website for more information and pricing.

Also included in this package is a RichView tuner. Some events on the Sun, notably active flares and coronal mass ejections (CME's) are extremely fast moving. If such features occur on the disc of the Sun, their high velocity towards the observer results in their wavelength being Doppler-shifted shorter than Ha. If the velocity is high enough, this wavelength could be outside the passband of the filter and the feature would not be observable. The RichView allows the user to de-tune the SolarMax slightly to bring such phenomena into better visibility. The RichView fits between the SolarMax and its adapter plate. A simple rotary wheel movement accomplishes the tilt necessary to move the passband of the filter. Because of the filter's position at the front end of the telescope, this does not compromise the performance of the filter nor limit the Ha field of view as is the case with rear-mounted filters.


Below you'll find a list of explanations regarding important accessories that may be required for this product.

  • An adapter plate is required to attach this filter to your telescope. Coronado is no longer producing these adapters however, Ashley Precision Parts is providing custom adapters for our customers. Please provide the telescope you will be adapting to, the outer diameter and whether you need a slip fit or threaded plate, in the comments section during check out. If you have any questions regarding these plates, please feel free to email our internet sales team for more information.

  • Important Note: OPT highly recommends a 2nd Day Air shipping upgrade on this product. Please read Coronado's Shipping Policy (PDF, 60K) for important information regarding this recommendation as your choice could affect the manufacturer's warranty!
Coronado Instruments Product Number: SMF40-15


Aperture40 mm (1.57")
Blocking Filter Barrel Size1.25"
Emission LineAlpha
Filter TypeH Alpha
Free ShippingYes
Optimized For1500mm & Under
Warranty1 Year Warranty