What is minimum focus distance?

Minimum focus distance (MFD) is the closest distance from the sensor plane to the subject where the lens can still achieve focus. It is measured from the sensor plane (marked with a symbol on most camera bodies), not from the front of the lens. A shorter MFD allows closer focusing and higher magnification.

What is working distance?

Working distance is the physical gap between the front of the lens and the subject at minimum focus distance. It equals MFD minus the lens length. Working distance matters for macro, wildlife and product photography — too short and you may cast shadows or scare subjects.

How does MFD relate to magnification?

Maximum magnification occurs at minimum focus distance. Magnification = focal length / (MFD - focal length). Macro lenses have short MFDs relative to their focal length, achieving 1:1 (1x) magnification. Standard lenses typically achieve only 0.1-0.25x magnification.

Can I focus closer than the rated MFD?

Not optically. However, extension tubes, close-up dioptre filters, or reversing the lens can all reduce the effective MFD and increase magnification. Extension tubes maintain optical quality but reduce the focus range to infinity. Close-up filters are convenient but may reduce sharpness.

PhotoCalcs

Minimum Focus Distance Calculator — Working Distance & Magnification

Find the working distance and maximum magnification at your lens minimum focus distance.

Focal Length

Lens focal length

Minimum Focus Distance

From sensor plane to subject

Sensor Width

e.g. 36mm for full frame

Lens Physical Length

Length of lens barrel

How We Calculate This

This calculator determines the magnification and working distance at minimum focus:

Magnification at MFD

M = focal length / (MFD - focal length)

Working Distance

Working distance = MFD - lens physical length

Subject Coverage

Subject width = sensor width / magnification

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.