Magnetic mount eclipse filter for a phone camera

During the October annular eclipse I experimented with taping a safe solar viewer card to my phone to take images of the eclipse. This technique works well when used with a camera app that supports manual exposure settings. Anyone can take photos of the partially eclipsed sun in addition to the many interesting shots of people and the environment possible during the partial phases of a solar eclipse.

Later I found inexpensive solar filter cards designed for camera phones. These fit better over the multiple lens array on my phone. But needed to be taped in place or held by hand to the back of your phone camera. I knew from my October experiece that this didn't work very well and would be even more awkward in a total eclipse where you need to accurately place and remove the filter for different stages of the eclipse.

Recent Apple camera phones have come with the MagSafe magnetic attachment system for chargers and accessories. Many older phones can be retrofitted with cases that support MagSafe accessories. The new Qi2 charging standard has adapted this technology, so it is likely to be common on all camera phones in the future. I decide to build a magsafe phone camera attachmet for eclipse filters. The result is easy to use, robust, and cost less than $20 for two.

Materials needed:

  • Solar filter card. I used one designed for a camera phone but almost any eclipse glasses, viewing card, or safe solar viewing film could be adapted for this purpose.
  • Filter support spacer. I used a 2.25" square piece of 1/8" plexiglass made from some scrap I had, but cardbord or thin wood could be used as well. It needs to be thick enough to so that any lens bump on the back of the camera won't interfere with the filter card.
  • Thin magnetic metal ring. I found many companies selling these inexpensively online. They are used to convert old phone cases or make DIY MagSafe phone mounts.
  • Some rubber cement to glue the support spacer to the filter card.

To assemble:

  1. If your phone or case doesn't have a magsafe connector, get a conversion case with one. The thin metal rings for the adapter are not strong enough on their own to do the job.
  2. Next cut your spacers to 2.25" square, large enough to cover the MagSafe connector
  3. Put a thin metal magnetic ring in place on the back of the phone case, shiny metal side down. Peal the protective paper off of the adhesive side of the ring.
  4. Position the spacer centered over the ring. On my iPhones this was snug against the protective lip on the case. Press the spacer firmly to set the adhesive and let it rest a couple of mintues in position.
  5. Position the solar film filter on the spacer so that it covers all the camera lenses on the phone. Mark the cardboard holder of the solar film wher it will contact the plastic spacer.
  6. Apply rubber cement to the solar filter card where it will contact the spacer. Be careful not to get any on the solar film itself.
  7. Position the solar filter card with glue on the spacer and press down.

Ready to stick the spacer to the adhesive metal ring

Two completed MagSafe mountable filters

Phone and empty case with filters mounted

Find out more about safe solar filters.

Content created: 2024-03-10




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