Magnification ratio from focus distance.
Calculate the magnification ratio precisely from the focus distance set on your lens – using the full optical formulas instead of rough approximations.
Delivers subject distance, image distance, magnification and exposure factor in one go – perfect for macro and close-up planning.
- ◆Subject + image distance
- ◆Exposure factor
- ◆All lenses
- ◆Scientific
Magnification Calculator
Calculate the magnification ratio based on the focus distance setting
Input Parameters
Minimum distance: 0.20m at 50mm
Calculation Basis:
- • Based on the focus distance setting on the lens
- • Takes into account the optical laws of the lens equation
- • Automatic exposure compensation calculation
- • Accurate for all lens types
Calculation Results
Important Notes:
- • Based on the focus distance setting on the lens
- • Considers physical optics laws
- • For close-ups, the image distance changes
- • TTL metering compensates automatically
- • Practical values may differ slightly
Magnification ratio and focus distance.
The magnification ratio shows how large a subject is rendered on the sensor relative to its real size. It depends directly on focus distance and focal length.
What distance really means.
The focus distance set on the lens is not identical to the real subject distance. The calculator derives the real distance using the lens equation:
- Focus distance: value shown on the lens
- Subject distance: real distance to the subject
- Image distance: lens to sensor/film
What the calculator helps with.
- Determine the exact magnification ratio
- Calculate exposure correction
- Plan macro shots
- Understand the optical relationships
- Focus precisely in close-up work
In close-ups the image distance grows, which lets less light reach the sensor. The extension factor is calculated as (1 + M)².
Four formulas, one consistent picture.
The calculator combines four standard equations of geometric optics – so subject distance, image distance, magnification and exposure factor all line up.
Magnification scale and categories.
A cheat sheet from wide-angle photography to extreme macro – including exposure factors for quick judgement.
| Magnification | Ratio | Category | Exposure factor |
|---|---|---|---|
| 0.05× | 1:20 | Normal / wide-angle | 1.1× (+0.1 stops) |
| 0.25× | 1:4 | Close-up | 1.6× (+0.7 stops) |
| 0.5× | 1:2 | Near-macro | 2.3× (+1.2 stops) |
| 1.0× | 1:1 | Macro photography | 4.0× (+2.0 stops) |
| 2.0× | 2:1 | Extreme macro | 9.0× (+3.2 stops) |
Five pointers for magnification photography.
Answers to common questions.
Related tools.
These calculators match the current tool and extend your workflow.
Solid photography knowledge.
Calculators give you the number. On the blog and in 1:1 coaching I turn theory into results you can see in your images.