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Orion 12.31" ID Full Aperture Solar Filter - 07783

SKU: ORI-07783
To ensure that the solar filter you buy will fit properly, please take a few moments and measure the outside diameter of your telescope, spotting scope or binoculars before you order. Remember, the solar filter needs to fit snugly around the front of the tube assembly that holds the optics. If the filter is slightly larger than its diameter, the filter can be made to fit by the addition of self-stick felt spacers to the inside of the cell. However, if the filter is too small it will not fit, and that would be a shame. So please, measure before you order. Thanks.

Orion 12.31" ID Full Aperture Glass Solar Filter for 11" SCT


  • A required accessory for safely viewing the Sun with an 11" Schmidt-Cassegrain to avoid eye damage.
  • This solar filter features 12.31" inside diameter and tightly fits over your 11" SCT's front aperture to block 99.999% of incoming sunlight.
  • Machine-polished glass elements are triple-coated with nickel-chromium stainless steel.
  • Each Orion solar filter is mounted in an aluminum cell lined with foam and has three equidistant securing thumbscrews, as well as four 1/16" thick and four 1/8" thick adhesive foam tabs to allow a customized friction fit to your optical tube.
  • Note: Orion solar filters are made to be used with sufficient friction fit attachment. Thumbscrews should ONLY be used to maintain secure filter placement after a friction fit has been attained.


Astronomy does not have to be completely done in the dark. Turning your telescope towards our closest star is a fun and educational experience. Observe the movement of giant sunspots, the clouds of glowing photosphere vapor, and solar "granulation" detail. But make sure to protect your eyes by using a safe Orion solar filter! Directly viewing the Sun without one, even for a millisecond, can cause permanent damage to your eyes.

Superior to Mylar

For breathtaking views of the Sun without putting your eyes in jeopardy, this 12.31" ID Glass Solar Filter from Orion delivers. While glass solar filters may be costlier compared to Mylar filters, they offer better contrast, a more organic yellow-orange color instead of blue, and more durability due to their glass and aluminum construction. Glass filters are optimal for solar photography too!

The glass elements of this Orion Full Aperture Solar Filter are machine-polished and thrice-coated using an advanced nickel-chromium stainless steel to provide a scratch-resistant surface. This filter only allows a minuscule fraction of incoming sunlight to pass, blocking unsafe ultraviolet and infrared radiation.

This Orion filter is mounted in an aluminum cell that comfortably slides over the front of your telescope. Fits 11" Schmidt-Cassegrain Telescopes, but will also fit up to 1/4" smaller diameter telescopes with foam tape liner applied.

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).