Coronado SolarMax II 90 H-Alpha Filter w/ BF15

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Coronado SolarMax II 90 H-Alpha Filter w/ BF15

Coronado SolarMax 90 H-Alpha Filter System

The Coronado Instruments SolarMax 90 is a thermally stable H-alpha filter for installation on the front of the user's telescope. Its 90mm aperture and <0.7A bandwidth provide very high resolution and result in unsurpassed views of the finest surface details and prominences when mounted on a good quality telescope. The Coronado SolarMax-90 is threaded to fit directly to the TV 101, 102 and Genesis SdF instruments, but will mount on most other telescopes using a suitable adaptor plate (sold separately, choose from options below, or, if you do not see the adapter for your telescope, call the store for more information).

This package price is for the SolarMax 90, the BF-15 Blocking Filter (for scopes with a focal length of 1500mm or less), and a RichView tuner. If you have a telescope with a focal length of less than 1000mm, see the SolarMax 90/BF10 package. If your telescope has a focal length of 1501-3000mm, you'll need the SolarMax 90 with the BF30. You can find these products in this same category.

About the BF15 Blocking Filter:

A blocking filter is a secondary interference filter which mounts at the eyepiece end of the telescope. You must use this filter in conjunction with the front narrowband element (SolarMax 90)....either component cannot be used alone. The BF15 is specifically optimized to produce a full disc image on telescopes with a focal length of up to 1500mm. It is a 1.25" right-angled diagonal unit.

About the 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 tuner allows the user to de-tune the SolarMax II slightly to bring such phenomena into better visibility. The RichView fits between the SolarMax II and its adaptor plate. A simple rotary wheel movement accomplishes the tilt necessary to move the passband of the filter. Because of the filter 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. To add them to your order, just click on the "Accessories" tab and choose the appropriate items.

  • 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 new Shipping Policy (PDF, 60K) for important information regarding this recommendation...your choice could affect the manufacturer's warranty!

Coronado Instruments Product Number: SMF90-15


Aperture90 mm (3.54")
Blocking Filter Barrel Size1.25"
Emission LineH Alpha
Filter TypeH Alpha
Free ShippingYes
Optimized For600mm & Under
Warranty1 Year Warranty
Wavelength<0.7 A