Optics April 20, 2026 4 min read

Minimum Focus Distance: What It Really Means (and What It Doesn't)

Minimum focus distance appears on every lens spec sheet, and most people read it as how close they can get to the subject. That is not quite right, and the gap between what it measures and what you actually need matters every time you work at close range.

What it measures

Minimum focus distance is measured from the focal plane, the sensor inside the camera, to the subject. Not from the front of the lens, and not from the mount. Most cameras have a small mark on the top plate, a circle with a line through it, showing where the sensor sits. A tape measure from that mark to the subject at closest focus gives the figure on the spec sheet.

What you feel in the field is the working distance, from the front of the lens to the subject. It is shorter by the lens's length and by the distance from the sensor to the mount, called the flange distance, about 16 to 20 mm on mirrorless cameras (roughly 16 mm for Nikon Z, 18 for Sony E, 20 for Canon RF) and 44 to 46 mm on DSLRs.

So the working distance is approximately the minimum focus distance minus the flange distance minus the lens length.

Worked examples

The Sony FE 90mm f/2.8 Macro G OSS has a minimum focus distance of 28 cm and is 130.5 mm long. On a Sony body, 280 minus 130.5 minus 18 gives about 13 cm. The Nikon Z MC 105mm f/2.8 VR S has a minimum focus distance of 29 cm and a length of 140 mm. On a Z body, 290 minus 140 minus 16 gives about 13 cm. Check the method against a measured case: the Canon EF 100mm f/2.8 Macro focuses to 31 cm and is 123 mm long, and on a DSLR with a 44 mm flange distance that works out at about 14 cm. Measurements of the actual lens give about 15 cm. The formula lands within a centimetre or two, as long as the lens does not change length when it focuses, as many internal-focus macros do not. A lens hood takes a further bite, so subtract its length if you use one.

How working distance scales

For macro lenses, the working distance at 1:1 is about 45 to 50 percent of the minimum focus distance. Measured examples from Canon's range: the EF-S 60 mm has a minimum focus distance of about 20 cm and a working distance of about 9 cm, the EF 100 mm about 31 and 15 cm, and the EF 180 mm about 48 and 24 cm. That is why long macros give so much more room, even though their minimum focus distances look similar on the spec sheet. For more on choosing, see macro photography working distance.

Minimum focus distance versus magnification

Maximum magnification says how large the subject appears on the sensor. At 1:1, a 10 mm subject covers 10 mm of sensor, and at 0.5:1 it covers 5 mm. For close-up work, magnification is usually the more useful spec. A lens with a short minimum focus distance but low magnification lets you get physically close without making the subject large, while a lens with a longer minimum focus distance but 1:1 magnification fills the frame from further back. Higher magnification also means shallower depth of field, and at 1:1 and f/8 the whole zone is under a millimetre deep, as the diffraction post notes.

Long lenses

At the other end, super-telephoto lenses have long minimum focus distances, often 2 m or more. That seldom matters for birds at 20 m. It can matter for a perched bird that lets you approach closely, or for a butterfly at 3 m, where a lens that cannot focus that near is no use. Check the figure if you plan to shoot near subjects with a long lens.

Measuring it with the calculator

You can find a lens's actual close-focus performance without a spec sheet, which helps for vintage and third-party lenses. Focus at the closest distance on an object of known size, take a photo, measure the object's pixel height, and enter the sensor height, the image height in pixels, the focal length and the actual size in the calculator. One caveat: the calculator uses the simple thin-lens formula, so the distance it returns is measured from roughly the middle of the lens, not from the sensor or the front element. At 1:1 with a 100 mm macro, the formula gives about 20 cm, which is twice the focal length, while the gap you would measure from the front of the lens is about 15 cm. So treat the result as a few centimetres more than the front-element distance.

Know which number you are reading. The spec sheet quotes sensor to subject, what you feel is lens front to subject, and the calculator gives something in between.