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AstroZap Baader Solar Filter for ETX 90 and 90 mm - 100 mm Telescopes

Astro Zap Baader Solar Filter for ETX 90 and 90 mm - 100 mm Telescopes

    • AstroSolar is one of the best solar filters on the market today!
    • AstroSolar has a neutral color balance.
  • AstroSolar allows you observers to focus on certain spectral passbands for investigations of different layers within the solar "atmosphere".

Baader AstroSolar is unlike any other solar filter on the market! The sun appears in neutral white when using AstroSolar providing and exceptional observing experience. Other films and some glass filters produce blurry reddish or bluish Solar images which in turn cuts part of the spectrum. Faculae regions, which are visible mostly in the blue wing of the spectrum, are very hard to see with an orange sun. Because of the neutral color balance of AstroSolar, you can use various color (or interference) filters. This allows observers to focus on certain spectral passbands for investigations of different layers within the solar "atmosphere".

The uniqueness of Baader AstroSolar is not only in its ability to observe the sun using one of the best filters out there but also because of the dedication in making it one of the safest filters around. All processes in correlation to this product have been carefully tested and coatings are continuously inspected for consistency to ensure your eye safety. Further more, the National Bureau of Standards in Germany, the PTB has approved Baader AstroSolar for eye safety.AstroSolar is essentially free from pinholes. Because of the coating on both sides, the probability of two pinholes overlapping each other is tremendously faint. There can be a time when pinholes do appear but to 1 out of 1000 only in optical density 2.5! Baader AstroSolar film Filter cell is constructed of lightweight 18Ga. aluminum and powder coated white. To ensure a secure fit, the Filter cell has heavy duty threaded inserts and nylon thumbscrews.

What About Your Finderscope?

Adding this solar filter to your telescope will adequately filter the light coming through your focuser, but have you considered what you’ll do about your finder scope?

Here are some suggestions for dealing with your finder that will assure you do not damage your eyes (or anyone else’s) by looking at the Sun through your telescope’s unfiltered finder:

    • Remove Your Finder. Ditching your finderscope when solar viewing will remove the possibility of someone accidentally looking through it to spot the Sun. Of course, not having a finder makes centering the Sun in your eyepiece more difficult, but with practice, it can be done. Set the mount down so the telescope is pointing in the direction of the Sun. Put the main solar filter on so you can check your progress, and then move the telescope around until it casts a shadow that produces a nice, sharp silhouette of the scope. The OTA will look circular. Now move your telescope up or down with your hand controller, slow motion controls, or very carefully by hand if required while looking through the eyepiece. You will not get a warning when you are close, but you should be able to align with the Sun using this method. Practice ahead of time before any big event, like an eclipse, to make sure you’ve got the process down.


    • Filter Your Optical Finder. This solution is not recommended for a reflex or red dot finder since it is too easy to accidentally look around the window. If you have one of these finders we recommend you either remove it or replace it with a dedicated solar finder (see below).


      To make your optical finderscope safe for solar viewing you’ll need to buy a piece of Baader Solar Film for Visual Use. This film comes in different size sheets and cuts easily with scissors, allowing you to make your own filter. You can go super low-tech and use a rubber band to hold a piece of the film firmly around the finder or you can get fancy and build your own slip-on solar filter. However you attach the solar film, you need to make sure there are no light leaks at all and that it doesn’t accidentally fall off when you move your telescope around. Any unused film can store flat between two pieces of cardboard and will keep for years. It is nice to have around, just in case of a solar emergency :-)


  • Buy a Dedicated Solar Finder. Check out the Tele Vue Sol-Searcher Solar Finder. This special finder can only be used when observing the Sun, but it works very well. The Sol-Searcher is reasonably priced and can be attached to your telescope with Velcro or with #10-32 screws (user supplied).

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