Magnifying glass

A magnifying glass uses a converging optical lens to present an upright enlarged virtual image. For focal length $f$ and eye near point distance $D$, the near-eye angular magnification is $D/f$ with a relaxed eye, or $1+D/f$ with the virtual image at the near point. These formulas assume negligible eyepiece-to-eye distance. With eye-to-lens distance $e$, object distance $u$, and the virtual image at the eye's near point, the angular magnification is $(D-e)/u$.