Minimum Focus Distance Calculator

| Added in Miscellaneous

What is Minimum Focus Distance and Why Should You Care?

Minimum Focus Distance (MFD) is the closest distance at which your camera lens can focus on a subject while maintaining a sharp image. Understanding MFD helps photographers avoid blurry close-up shots and achieve crystal-clear detail.

Whether you're a portrait photographer, product shooter, or macro enthusiast, knowing your lens's MFD is essential for getting the shots you want.

How to Calculate Minimum Focus Distance

The formula for calculating minimum focus distance is:

[\text{MFD (mm)} = \text{Focal Length (mm)} \times 4 + \text{Distance Between Nodal Points (mm)}]

Where:

  • MFD is the minimum focus distance in millimeters
  • Focal Length is the lens focal length in millimeters
  • Distance Between Nodal Points is the space between the lens's principal points

Calculation Example

For a lens with a 50mm focal length and 20mm nodal point distance:

[\text{MFD} = 50 \times 4 + 20 = 200 + 20 = 220 \text{ mm}]

The minimum focus distance is 220mm, or about 8.7 inches.

Typical Minimum Focus Distances

Lens Type Typical MFD
50mm Prime 450mm
85mm Portrait 850mm
100mm Macro 300mm
24-70mm Zoom 380mm
70-200mm Telephoto 1200mm

Tips for Close-Up Photography

  • Use a dedicated macro lens for the shortest MFD
  • Extension tubes can reduce MFD on any lens
  • Close-up filters offer an affordable option for closer focusing
  • Consider working distance for lighting and subject comfort

Frequently Asked Questions

Minimum focus distance is the closest distance from the camera sensor at which a lens can focus on a subject while still producing a sharp image.

Knowing the minimum focus distance helps photographers understand how close they can get to subjects, which is especially important for macro and product photography.

Nodal points are specific points within a lens system where light rays appear to converge or diverge. The distance between them affects various optical calculations.

You can use extension tubes, close-up filters, or macro lenses to reduce the minimum focus distance and get closer to your subject.