Magnifiers are commonly used for electronics repair jewelry inspection handicraft creation and quality checking and they function based on the light refraction of convex lenses

We can easily understand this rule with the candle imaging experiment when a candle is placed inside the focal length of a convex lens the lens forms a large upright virtual image just like how a magnifier works

If the convex lens has a longer focal length the candle image will be relatively smaller and we can keep more space between the lens and the candle the viewing range also becomes wider

If the convex lens has a shorter focal length the candle image gets much bigger yet we have to move the lens very close to the candle and the visible area will narrow down

When the object being observed sits within the focal length of a convex lens light passing through the lens refracts and converges our eyes then perceive an upright enlarged virtual image which makes tiny subtle details visible

One key optical trait worth noting lenses with shorter focal length deliver stronger magnification yet they come with shorter working distance and narrower field of view this is why high-power magnifiers need to stay close to workpieces

Low-grade lenses often bring distorted images and color deviation which can interfere with precise inspection professional optical lenses are refined for better light transmission and less distortion for magnifying lamps matched soft even lighting helps cut shadows and glare easing eye strain during long close work