Solar filter for the Canon RF 100-500mm F4.5-7.1 L IS USM lens.

Solar filter for the Canon RF 100-500mm F4.5-7.1 L IS USM lens.

This solar filter fits snugly on the end of the lens. You will need the actual solar film to construct this as the 3D printed parts are only the frame. You can buy this on Amazon or any telescope supply company. I like both Thousand Oaks Optical “SolarLite” film, which gives a yellowish cast to the sun, and Baader AstroSolar ND5.0 Visual solar film, which gives a more natural white (slight bluish) cast to the sun. A 4"x4" sheet is large enough as the actual film is cut to a 89mm diameter. Use the cutting template and razor knife to cut the film.

I designed this cap to only fit the end of the lens that extends. With the lens retracted, it still fits in place. There is room for a standard screw filter installed, like a UV filter used for protection of the objective lens. It works with this filter or without and fits snugly on the end of the lens and should stay without falling off.

This is a threaded design the the solar film is held in place by pinching it in between the body and cap. They are threaded with a ultra-fine M90x1 thread.  This thread can be frustrating with 3D printed parts, but some patience is useful. Use a 0.4mm nozzle and very fine layer height for the threaded feature (0.07mm - 0.10mm layer height). Use variable layer height for the body as the rest of the body can be made with 0.30mm layer height. I like PLA+ for these and have had better luck with PLA+ than PETG for fine threads like this. Work the threads in by twisting back and forth and then cleaning any plastic debris/dust and the then the threads should be relatively smooth. Finally, assemble the filter with the film.