説明

• Taking hearth with Fresnel lens has excessive requirements for weather, temperature and igniter When taking fire within the field, the effect of the lens is far lower than that of the flint, and its practicability is deficient It is suitable for physics teaching and expansion actions Please put on sunglasses when utilizing it to bypass looking straight on the solid gentle for decades Weather on the day of shooting: sunny, temperature 30 °C The Fresnel lens has a circle of concentric circles at the front and a smooth floor at the reverse, with a thickness of 1, and the sting and middle have an analogous thickness In operation, the concentric (non-smooth) facet of the lens faces the solar Or look at the logo, the aspect with the be aware "UP" faces the solar

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レビュー