Magnification of a Lens Calculator
Calculate lens magnification, image distance, and optical properties for photography and optics
Lens Magnification Calculator
Distance from lens center to focal point
Total distance from object to image sensor
Additional distance between lens and sensor for macro photography
Example Calculation
Photography Example: 200mm Telephoto Lens
Focal length: 200mm telephoto lens
Subject distance: 10 meters (bird photography)
Calculation: d = 10m = 10,000mm, f = 200mm
Formula: r = √(d²/4 - f×d) = √(25,000,000 - 2,000,000) = 4,796mm
Results
Object distance (g) = d/2 + r = 9,796mm
Image distance (h) = d/2 - r = 204mm
Magnification = h/g = 0.0208×
A 2-meter tall bird would appear as 4.16cm on the sensor
Common Lens Types
Optical Tips
Magnification < 1 means image is smaller than object (typical in photography)
Magnification = 1 creates a 1:1 life-size image
Extension tubes increase magnification for macro photography
Longer focal lengths provide higher magnification at same distance
Don't confuse magnification with zoom (optical vs. focal length range)
Understanding Lens Magnification
What is Lens Magnification?
Lens magnification is the ratio between the height of the image formed on the sensor (or film) and the height of the actual object being photographed. In most photography scenarios, this value is less than 1, meaning the image is smaller than the actual object.
Why is it Important?
- •Determines how large subjects appear in your photos
- •Critical for macro and close-up photography
- •Helps plan composition and framing
- •Essential for scientific and technical photography
Magnification Formulas
m = h/g
(Basic magnification formula)
m = (d/2 - r) / (d/2 + r)
(Using focal length and object distance)
- m: Magnification ratio
- h: Image distance (lens to sensor)
- g: Object distance (object to lens)
- d: Total distance (object to sensor)
- r: √(d²/4 - f×d)
Magnification vs. Zoom
Magnification
- • Absolute measure of image size
- • Usually < 1 in photography
- • Depends on distance and focal length
- • Example: 0.025× (1/40th actual size)
Zoom
- • Range of focal lengths available
- • Marketing term for variable lenses
- • Example: 3× zoom (18-55mm lens)
- • Not directly related to magnification
Practical Applications
Wildlife Photography
- • Long telephoto lenses (400-800mm)
- • Low magnification (0.001-0.01×)
- • Maintain safe distance
- • Fill frame with distant subjects
Macro Photography
- • Magnification ≥ 1× (life-size or larger)
- • Extension tubes increase magnification
- • Focus on tiny subjects
- • Specialized macro lenses
Portrait Photography
- • Medium telephoto (85-135mm)
- • Moderate magnification (0.1-0.3×)
- • Flattering perspective
- • Pleasant background blur