10 Pack Fresnel Lens Magnifying Sheets - Reading, Solar Oven + DIY Projection TV Lenses

Love these for all sorts of applications. Great physics toy and good for those with reduced or impaired vision. If inappropriately used by young kids they can burn the house down. Just what I needed when I was growing up. Close ring spacing does make them useful for reading and examining smaller details in objects, etc. Great value!

My child was able to start a fire instantly! I couldn’t believe it. He sold the others to his classmates and I think we broke even. Class had a science project to do and he got an A!

Easy. Works well.

These were fun to use and play with for our science fair projects.

With their relatively large area, these fresnel lenses will burn paper on a cloudless day, when brought to a focus on dry paper. I include one in my camping back pack for emergency fire starting. Of course they are also good as reading magnifiers or such. My only complaint is that they are too thin to stay flat and ridged. I expect you could easily build one into a frame to fix that.

Does what it does.

A few small blemishes on most of them, generally near edges, and all 10 are usable. Focal length of 300mm seems accurate. They are a bit on the flimsy side, and do better attached to a stiffer border frame (3d printed or whatever); they are soft and easily scratched, so optionally add a plexiglass or glass covering. I'm using one for the top front of a portable solder-fume exhaust station/hood -- magnification while keeping smoke out of my eyes.

You don’t even need to hold it carefully in place, it will start a fire immediately!