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| This 90mm aperture H-alpha filter can be used with virtually any telescope – but it will work best with telescopes having a focal length of 1500mm to 3000mm, particularly with long focal ratio refractors. The front filter element (containing the ERF and etalon) is threaded to mount directly into the front cell of TeleVue TV-102 and NP-101 refractors, but will require an optional custom mounting plate for installation on other telescopes. With catadioptric telescopes, the front filter element must be mounted off-axis to avoid being blocked by the telescope’s secondary obstruction. This would effectively limit this 90mm filter’s use with catadioptric scopes to those with apertures 11" and larger, as even a 10" scope has only an 80mm clear expanse between the secondary obstruction and the edge of the corrector and would block some of the filter’s clear aperture and limit resolution. Its 90mm aperture and <0.7A bandwidth provide exceptionally high resolution and contrast and result in unsurpassed views of the finest surface details and prominences when mounted on a good quality telescope. This package is provided with a straight-through 30mm clear aperture blocking filter for use with 2" star diagonals and accessories or where full disc viewing is required on telescopes with a focal length greater than 1500mm. Some events on the Sun – notably active flares and coronal mass ejections (CMEs) – are extremely fast moving. If such features occur on the disc of the Sun, rather than on the limb, their high velocity towards the observer results in their wavelength being Doppler-shifted to a shorter wavelength than the H-alpha line. If the velocity is high enough, this Doppler-shifted wavelength could be outside the passband of the filter and the feature would not be observable. Coronado includes a T-Max mechanical tuning mechanism to allow the user to de-tune the SolarMax slightly from the H-alpha line to make such Doppler-shifted phenomena more visible. The T-Max fits between the SolarMax and its adaptor plate at the front of the scope, but is not shown in the image. 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 H-alpha field of view as is the case with rear mounted filters.
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Terms of Sale | PRIVACY POLICY 7/1/2004 | Fine Print
Toll-Free Telephone Astronomics: 800-422-7876; Christophers, Ltd.: 800-356-6603
Alternate Telephone: 405-364-0858 24 Hour Fax Line: 405-447-3337
Telephone Hours: Monday 8 AM - 6 PM CST
Tuesday-Friday 8 AM - 8 PM CST
Saturday Noon - 5 PM CST
Store Hours: Monday-Friday 9 AM - 5 PM CST
Saturday Noon - 5 PM CST
Astronomics / Christophers, Ltd.
680 S.W. 24th Ave.
Norman, OK, 73069
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