Determining the Correct Orion Solar Filter for your Telescope
A full-aperture solar filter is designed to fit over the front of a telescope. It allows safe viewing of the Sun by reducing the light by 99.99% and preventing concentrated heat from entering the telescope, which could cause injury to the user or damage to equipment.
If your telescope is not listed on our solar filter reference chart, you can determine the size of filter needed for your scope by taking the following steps:
- Measure the maximum outside diameter (OD) of the front end of your telescope.
- The solar filter sizes listed on our website refer to the inner diameter (ID) of the filter's foam-lined cell for Orion Solar Filters, which slip over the front of the telescope. Choose a filter whose size matches the OD of your telescope's front end, or that is up to 0.25 inches larger than the front end (for Orion Solar Filters only). For a filter that is up to 0.25" larger in diameter than your telescope, if the filter includes three thumbscrews, tighten them down gently and verify they grip the telescope tube wall securely without allowing the filter to slide off. If the filter includes foam shim material, stack enough shims together to ensure a snug slip-on fit where the filter will remain securely attached. A snug friction fit is required for safe usage.
Installing the Orion Solar Filter on Your Telescope
With the three thumbscrews backed out to just inside the wall of the metal cell, place the solar filter over the outside of the telescope. It may require some light force to push the filter in place. Make sure it is seated completely over the telescope. Then lightly tighten the thumbscrews to further secure the filter on the telescope.