Quote:
Originally Posted by rumples riot
The blocking filter is more to do with filling the field of view with varying focal lengths. The longer the focal length of any particular scope the larger the blocking filter has to be. If the blocking filter is too small it will cut off parts of the solar disk via vignetting.
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ah yes I see - btw i reread the ad blurb and saw this "It's all part of the Lunt Solar System H-Alpha Telescopes double pass system which has an estimated bandpass of <0.55 Angstroms and is capable to providing ultra high resolution and high contrast views of both surface and edge detail under good to excellent seeing conditions. "
so it is down around what you were talking about