Close-up lens calculator.
Calculate the magnification ratio when using close-up lenses (diopter filters) – the cheapest door into macro photography.
Includes diopter conversion, working distance and guidance on when close-up lenses beat extension tubes.
- ◆Diopter logic
- ◆Finite distance
- ◆Stackable
- ◆Working distance
Close-up Lens Calculator
Calculate the magnification ratio when using close-up lenses (close-up filters)
Input Parameters
Infinity setting yields approximate but practical results
Calculation Results
Important Notes:
- • Close-up lenses are an affordable alternative to macro lenses
- • Higher diopter values = higher magnification
- • Image quality may decrease at high diopter values
- • Close-up lenses can be combined (diopters add up)
- • Autofocus still works (on most systems)
Understanding and using close-up lenses.
Close-up lenses (diopter filters) are accessory lenses that screw onto the front of your lens. They act like a magnifying glass and significantly shorten the minimum focus distance.
How strong a close-up lens is.
The strength of close-up lenses is measured in diopters:
- +1 dpt – slight magnification (1000 mm focal length)
- +2 dpt – moderate magnification (500 mm focal length)
- +4 dpt – strong magnification (250 mm focal length)
- +10 dpt – extreme magnification (100 mm focal length)
When close-up lenses pay off.
- Flower photography (details of blossoms)
- Insect photography (longer working distances)
- Product photography (small objects)
- Texture shots (surfaces, structures)
- Cost-effective macro photography
Pros: very affordable, lightweight, no light loss, autofocus stays usable, compatible with virtually any lens.
Two formulas for two situations.
One simplified version for infinity setting, one precise formula for finite subject distances – pick whichever fits the situation.
Close-up lens focal length from diopters.
Formula: f_n = 1000 ÷ diopters (in mm)
Example: +2 diopters = 1000 ÷ 2 = 500 mm focal length
Close-up lenses vs. other macro methods.
Three classic ways into macro – each with its own strengths. This overview helps you decide.
| Method | Cost | Image quality | Light loss | Autofocus |
|---|---|---|---|---|
| Close-up lenses | Very cheap | Medium | None | Yes |
| Extension tubes | Medium | High | 1 – 2 stops | Limited |
| Macro lens | Expensive | Very high | None | Yes |
Five pointers for close-up lens photography.
Answers to common questions.
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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.