AstroZap Visual Baader Solar Filter for 205 mm - 215 mm OD Telescopes

This Baader AstroSolar™ Filter cell is powder coated white and fits telescopes with a 205 mm to 215 mm outside diameter range. The cell is constructed from lightweight 18Ga. aluminum. Nylon thumbscrews and heavy-duty threaded inserts secure a proper fit. Please remember to measure the outside diameter of your optical tube before going through with your order.

The Sun is displayed in neutral white with Baader AstroSolar™ safety film. Different films, along with some glass filters, produce a hazy bluish or reddish Solar image so that the spectrum is reduced. Particularly with an orange sun, it can be hard to find faculae areas which are distinguishable in the blue spectral region for the most part.

Baader AstroSolar film neutral color balance allows the user to hone in on individual spectral passbands in order to investigate distinct solar "atmosphere" layers by enabling the use of a variety of color (or interference) filters.

AstroSolar™ is virtually pinhole-free due to it being coated on each side, making the possibility of two overlapping pinholes extremely unlikely. Some glass filters don't always have coatings on both sides, even some of the more expensive filters. Pinholes do appear, however, but in only 1 out of 10,000 and only in optical density 2.5! Germany's National Bureau of Standards, the PTB, has approved Baader AstroSolar™ film for eye safety. Contrary to other available solar filters, AstroSolar™ film is CE-tested per EG-Norm 89/686 and EN 169/92 (notified body 0196). All processes associated with this product have been tested exhaustively. Coatings are scrutinized regularly for consistency to guarantee safety for your eyes.

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).