Dial in close-up focus without guesswork today. Choose lens setting and subject distance, get diopters. See both planes sharp, even in one take smoothly.
A split diopter changes focus for only part of the frame. One half stays at the lens focus distance, while the other half focuses closer (or farther) depending on diopter power.
Keep the split line hidden in a natural edge (door frame, face profile, foreground object). Stopping down increases depth of field and makes alignment easier.
| Diopter (D) | Focus distance (m) | Focus distance (ft) | Common use |
|---|---|---|---|
| 0.5 | 2.0 | 6.56 | Subtle foreground separation |
| 1 | 1.0 | 3.28 | Medium close foreground |
| 2 | 0.5 | 1.64 | Strong close-up focus |
| 3 | 0.333 | 1.09 | Very close foreground details |
| 4 | 0.25 | 0.82 | Extreme split diopter look |
Diopters are measured in inverse meters. A close-up filter adds optical power to the lens. The planning relationship is:
Rearranged forms used in this tool: s' = 1 / (1/s + D) and D = 1/s' − 1/s. If s is infinity, then s' ≈ 1/D.
A diopter is optical power measured in inverse meters. A value of 2 diopters adds 2 m−1 of power. When the lens is focused to infinity, the diopter’s sharp distance is about 1/D. So 2 diopters focuses near 0.5 m, while 1 diopter focuses near 1.0 m.
Split diopters keep a near subject and a far subject sharp at the same time. The clear half preserves the lens focus plane, and the diopter half shifts the plane closer. This calculator models that shift so you can estimate distances before you set marks.
If you already own a split strength, Mode A tells you what distance becomes sharp in the diopter portion when your lens is set to a known focus distance. This helps when the far subject is fixed. Place the foreground subject near the computed distance.
When the foreground distance is known, Mode B solves the required power using D = 1/near − 1/far. The tool also suggests a nearby common value, since many splits come in steps like 0.5, 1, 2, 3, and 4 diopters. Small rounding can move the sharp point.
For blocking and staging, Mode C is the fastest way to plan near and far planes. Enter the far plane you want the lens to hold, then enter the near plane you want the split to bring in. The output is the ideal strength, plus an optional preview if you enter a diopter you own.
The calculator accepts meters, centimeters, millimeters, feet, and inches. Pick one unit system and stay consistent when taping marks. Feet are common for blocking, while centimeters help for tabletop work. Conversions happen internally, so the math stays consistent.
This tool estimates focus distances, but the final look depends on aperture, focal length, and subject contrast. Stopping down increases depth of field and makes alignment easier near the split line. Very wide apertures can reveal the split edge and reduce tolerance for small distance errors.
Use the export buttons to save a result table, share it with your focus puller, and keep consistent marks across takes and setups today.
It lets you keep a close subject and a distant subject sharp in the same shot by splitting the frame into two focus planes. It is popular for dramatic staging and deep-focus storytelling.
No. It gives planning estimates. Lens breathing, filter quality, and depth of field can shift what looks sharp. Use the numbers to set marks, then confirm focus on your monitor.
When the lens is focused to infinity, the diopter half focuses at roughly 1 divided by the diopter value. That makes quick selection easier, especially for common strengths like 1 or 2.
Yes. Choose your preferred unit and enter all distances in that unit. The calculator converts internally, then returns results in the same unit for easy tape marking on set.
Pick the nearest available strength and re-check the predicted near distance. A slightly stronger value pulls focus closer, while a slightly weaker value pushes focus farther away.
Often yes. A smaller aperture increases depth of field on both planes and hides small placement errors. It can also reduce how obvious the split edge appears in the middle of the frame.
Place the boundary along a natural edge such as a door frame, a wall corner, or a subject profile. Keep the edge out of high-contrast textures and avoid fast movement across the split.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.