Magnification of a Lens Calculator
Calculate the magnification (reproduction ratio) of a lens based on focal length and subject distance. Understand how large your subject will appear on the sensor compared to its actual size.
Distance from lens to subject
How to Use This Calculator
- Enter your lens focal length in millimeters.
- Enter the distance from the lens to your subject in millimeters (focus distance).
- The calculator displays the magnification ratio (e.g., 0.5x, 1x, 2x).
- Use this to understand how large your subject will appear on the sensor compared to its actual size.
Magnification Formula
Magnification is calculated using the thin lens equation:
Example: A 100mm lens focused at 200mm from the subject: Magnification = 100 ÷ (200 - 100) = 1.0x (1:1 life-size reproduction).
Full Description
Magnification, also called reproduction ratio, is a crucial concept in photography, especially for macro and close-up work. It describes the relationship between the size of the subject in real life and the size of its image on the camera sensor. Understanding magnification helps you choose the right lens, plan your shots, and achieve the desired level of detail in your photographs.
Magnification is expressed as a ratio like 1:1 (life-size), 1:2 (half life-size), or 2:1 (twice life-size). A 1:1 ratio means the subject appears the same size on the sensor as it does in reality—this is the standard for true macro photography. Higher magnifications allow you to capture extreme detail, revealing textures and structures invisible to the naked eye.
This calculator helps you determine the magnification your lens will achieve at a given focus distance. Use it to plan macro shoots, understand lens capabilities, and ensure you can achieve the level of detail you need. Remember that magnification increases as you focus closer, but each lens has a minimum focus distance limit. Macro lenses are specifically designed to focus very close, enabling high magnification ratios.
Frequently Asked Questions
What is lens magnification?
Magnification (reproduction ratio) is the ratio of the image size on the sensor to the actual subject size. 1:1 (1x) means life-size—the subject appears the same size on the sensor as in real life. Higher magnification means the subject appears larger than life-size.
What magnification do I need for macro photography?
True macro photography typically requires 1:1 (1x) magnification or higher. Many "macro" lenses achieve 1:2 (0.5x) or 1:1. Some specialized macro setups can achieve 2:1, 3:1, or even higher magnifications for extreme close-ups.
How does subject distance affect magnification?
Closer subject distance increases magnification. As you move closer to your subject, the magnification increases. However, there's a minimum focus distance limit for each lens. Macro lenses are designed to focus very close, enabling high magnification.
What's the difference between magnification and zoom?
Magnification refers to the size relationship between subject and image (reproduction ratio). Zoom refers to the ability to change focal length. A zoom lens can change magnification by changing focal length, but magnification also depends on focus distance.