Reusable Mylar Solar Filter Enclosure

In preparation for the 2024 total solar eclipse, I needed a solar filter for imaging the partial eclipse phases. My plan was to use my Fujifilm FinePix SL1000 to photograph the eclipse, as it has a 50x bridge lens and I lacked a usable telescope for photography at the time. I bought a simple mylar solar filter sheet as it was cheap and could be customized to my needs. Many of the other projects I see involve either cutting up the mylar sheet or wrapping it around a tube with tape or rubber bands. However, I saw two potential issues with these methods: damage to the filter and inability to use the filter in other configurations. Instead, I opted for a “slide” configuration where the filter is kept flat in an envelope that can be inserted into a matte box made for the camera. Building a new matte box would allow me to reuse the same inexpensive filter for a different lens, and making a new envelope would allow me to increase the effective diameter of the filter if needed.

I started with some scrap materials: boxes, tape, cans, and cardboard mailers. Originally, I planned to use a soup can with both ends removed as the lens tube, but I abandoned this idea because of material sharpness and issues with the can’s diameter.

I marked and cut a hole in the cardboard mailer and lined the opening with painter’s tape to protect the edges from fraying. I added some more painter’s tape to hold the filter envelope closed on all sides. The finished slide-in filter looks like this:

Next, I made a lens tube from some corrugated cardboard and duck tape, and started cutting the matte box to shape:

I cut a slot in the top of the matte box and lined the frayed edges, and then did some very precise taping to connect the lens tube and the box.

Finally, I added some spacers made from packing foam to the matte box to correctly align the lens tube with the filter.

The final product looks a bit unimpressive, but I had no complaints about its functionality. Here is a shot of the sun through the filter box, with several sunspots clearly visible:

I later used this setup to photograph the 2024 total solar eclipse.