How To: Build a Solar Filter
This is a simple construction method for a solar filter to be fitted over the front of a camera lens. The filter in this case is a section of Baader film and is designed to fit the the end of a telephoto lens. Auto focus still functions correctly on my Canon EOS 350d.
This is a simple construction method for a solar filter to be fitted over the front of a camera lens. The filter in this case is a section of Baader film and is designed to fit the the end of a telephoto lens. Auto focus still functions correctly on my Canon EOS 350d.
I cannot vouch for the safety or reliability of this construction, I am merely documenting the construction of a solar filter of my own design. This is the filter that I use on my camera and have experienced no ill effects from its use. Due to the immense danger of looking at the sun I cannot advise you that you try or use my method and design, I merely present this to you to show you how I observe the Sun. I will not be held accountable or liable for any injury as a result of following these methods.
- Never, ever look at the Sun directly through any optical instrument - instant blindness could be the result. Even looking at the Sun with the eye can be harmful.
- DO NOT look at the Sun with magnifying glasses, cameras, binoculars or telescopes, any optical instrument in fact, without the use of a properly designed, approved and tested filter or specialised instrument.
- DO NOT use photographic film, smoked or tinted glass, plastic or metal film.
- Use only materials and instruments designed for the specific purpose for viewing the Sun.
- If in doubt, seek expert advice first!
That said, this is the design that I use when observing the sun and I can still see. If you have a digital camera that uses a lcd display, there should be no danger of injury as long as you mask out the sun with a screen, or similar. The suns light will not follow an optical path to your eye, but rather it will be visible in the lcd, which will only be as bright as the brightest pixel. This is only true for non- SLR cameras, or cameras without an optical viewfinder. If your camera has an optical viewfinder as well as a lcd display it would be a good idea to block off both ends of the viewfinder. You don't want to accidentally look at the sun. Before attempting this you should make sure that you never look directly at the sun at all. I recommend cutting a hole in a large piece of cardboard to poke the lens through. This will prevent you from accidentally looking at the sun and also the lcd will be clearer to see.
Once more: DO NOT LOOK DIRECTLY AT THE SUN. Instant blindness will be the result.
These are guidelines only and should not be taken as gospel.
The construction starts with a piece of corrugated cardboard. You could use any thick cardboard though. It must be strong and non translucent.
Start off by drawing around the outside of the lens so we know what size the hole should be.
Next mark out lines in a cross shape that will form the face and the walls.
Cut out the arms, making each one slightly tapered towards the outside.
Next, Using a template the same size as the inner face, cut out a section of Baader film.
Using some glue (I used some multi purpose adhesive) attach the film over the lens opening. Test a small amount of the glue on a spare piece of the solar film, as some will dissolve the protective coating, or the film itself. Others can make the film go cloudy.
That template we used earlier needs to have a hole cut into it the same size as the hole in the main face. It also needs to be cut to a smaller size than the face.
When suitably cut down, it should be stuck on top of the film, so that the film is sandwiched between the cardboard. Attach some foam strips to the outside edges of the sides. Wait for the glue to completely dry.
Fold the sides in on themselves and firmly attach with duck tape or gaffer tape. You should use several layers to ensure that no light can enter and that it is secure.
Finsihed. Here is a view inside the filter.
Remember, I cannot vouch for the safety or reliability of this construction, I am merely documenting the construction of a solar filter of my own design. If you do use it, you do so at your own risk. Please take notice of the warning at the top of the page. I will not be held accountable or liable for any injury as a result of following out this procedure.
- Never, ever look at the Sun directly through any optical instrument - instant blindness could be the result. Even looking at the Sun with the eye can be harmful.
- DO NOT look at the Sun with magnifying glasses, cameras, binoculars or telescopes, any optical instrument in fact, without the use of a properly designed, approved and tested filter or specialised instrument.
- DO NOT use photographic film, smoked or tinted glass, plastic or metal film.
- Use only materials and instruments designed for the specific purpose for viewing the Sun.
- If in doubt, seek expert advice first!
