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Thread: Suggest books to read about solar telescopes

  1. #1
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    Jun 2012
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    Question Suggest books to read about solar telescopes

    I need to find some books about the solar telescope designs, models, explanations about their features and various advantages and disadvantages. thanks.

  2. #2
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    Hi questionalways, welcome to the forum.

    Your post was delayed, because it happened to come at a time when we received a lot of spam messages to clean out. But you're here. I have no suggestion, but hopefully someone will.
    Forming opinions as we speak

  3. #3
    Join Date
    Dec 2006
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    I doubt any exist. Scopes for viewing the sun come in many specialized designs. Broadly you have broad spectrum ("white light") and narrow band that focuses in on part of a very specific spectral line, H alpha being the most common. White light scopes can use a projected image so an entire class can view at once or a filter (several types) over the front of the scope for viewing through an eyepiece by eye or camera. Front filters can be glass or mylar. Coatings can give a somewhat orange or blue sun depending on coating. Aluminum gives blue other alloys can give a more "natural" orange color. Blue is great for faculae but the color takes some getting used to. One design by John Dobson uses a front coated glass filter as the diagonal but is full aperture, no central obstruction. This has the advantage that if it falls off or is broken no light reaches the eye. It is not made commercially however. My experience is mylar filters are optically better than glass ones unless you pay a heavy price for optical glass. Then they are about equal. Wrinkles in the mylar are optically insignificant.

    Narrow band filters H alpha filters must be sub angsrom <0.1nm in band width to see surface detail. 0.7 angstrom (0.07nm) is considered the defacto minimum for this though prominences can be seen somewhat wider. Even 3 angstroms works with an occulting disk to block the sun.

    Sub angstrom filters usually have two parts. One is a multi layer interference stack that selects the specific frequency but will have specific frequencies out of band that it passes. Thus a second broad filter that passes the narrow band but blocks the "holes" is also needed. How the first is made varies somewhat by brand as does how they are tuned. Also where the two filters are placed varies as well. Daystar puts the "Energy Reduction Filter" in the front before the objective and the line specific filter before the eyepiece. This has the advantage that large apertures are nearly the same cost as small with the difference only in the considerably less expensive (per inch) blocking filter. But line filters work best at long f ratios, usually longer than f/30. This can be a problem to achieve without severely stopping down a large aperture scope. Though a Powermate (not ordinary barlow) can be used to help achieve this. I do that with my 10" f/5. A 3.5" EFR plus 2x5 power mate gives me a 90mm f/35 H alpha scope of 0.5 angstrom band width for far less than any other design but makes seeing the entire sun difficult.

    Most others put the narrow filter in front of the scope's objective and the blocking filter in the diagonal or before the eyepiece in some manner. This means the expensive narrow band filter must be the size of your objective which can get very expensive quickly as aperture goes up. They keep some cost down by using a simpler design for the narrow band filter but one that is of one band width. For narrower you have to stack two which nearly doubles the filter cost. But this system is at an infinite f ratio for all focal lengths of the scope since it is before any optics. This means it can be used with short focal length scopes for easy viewing of the entire sun.

    Both methods need some way to tune the narrow band filter as some features are best seen at slightly different frequencies. There are many ways of doing this from pressure on the filter, tilting it and by temperature control. Sometimes more than one method is used. My filter can be tilted and is at an oven controlled temperature. Ovens take electricity and time to reach temperature so poor for portable use.

    Read the reviews of the many filters and scopes out there for info on a specific design.

    Rick

  4. #4
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    I wonder if this might be helpful to the astronomy community in some way
    http://qwonn.com/black-ops-plastics.html

  5. #5
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    Quote Originally Posted by publiusr View Post
    I wonder if this might be helpful to the astronomy community in some way
    http://qwonn.com/black-ops-plastics.html
    publiusr

    Your post has pretty much nothing to do with the thread (it certainly isn't a book about solar telescopes) and it is offered with basically no information about what you are linking to. Please stay on topic and offer some description of things you link to; people shouldn't be required to clink a link to know what it is about.
    At night the stars put on a show for free (Carole King)

    All moderation in purple - The rules

  6. #6
    Join Date
    Jun 2012
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    I'd recommend Solar Observing Techniques By Chris Kitchin

  7. #7
    Join Date
    Feb 2011
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    25
    The "Solar Astronomy Handbook" is a very good and detailed read. It really covers most of what you are looking for.
    Will-bell sell it I think.

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