Taking fire with Fresnel lens has high requirements for weather, temperature and igniter. When taking fire in the field, the effect of the lens is far less than that of the flint, and its practicability is poor. It is suitable for physics teaching and expansion activities. Please wear sunglasses when using it to avoid looking directly at the strong light for a long time.

Weather on the day of shooting: sunny, temperature 30 °C

The Fresnel lens has a circle of concentric circles on the front and a smooth surface on the reverse, with a thickness of 1.8mm, and the edge and center have the same thickness.
In operation, the concentric (non-smooth) side of the lens faces the sun. Or look at the logo, the side with the word "UP" faces the sun.