任意の焦点距離、絞り、センサーサイズ、ピント距離から、過焦点距離と許容範囲内でシャープに写る近点・遠点を算出。風景写真に最適。
| 絞り | 過焦点距離 | 近点 | 遠点 | 被写界深度の合計 |
|---|
過焦点距離 H = f² ÷（N × c）+ f（fは焦点距離、Nは絞り値、cは許容錯乱円）。近点 =（H × s）÷（H +（s − f））。遠点 =（H × s）÷（H −（s − f））で、負の値は無限遠を意味します。
最大の被写界深度を得るには過焦点距離にピントを合わせます。H/2から無限遠までが実用上シャープに写ります。
Hyperfocal distance is computed as H = f squared / (N x c) + f, where f is focal length, N the f-number and c the circle of confusion for your sensor. Near and far limits come from the standard depth-of-field pair: near = (H x s) / (H + (s - f)) and far = (H x s) / (H - (s - f)), with s your focus distance. When that far denominator falls to zero or below, the tool prints infinity.
The Sensor (CoC) dropdown is the setting most people overlook, and it feeds c directly: 0.030 mm for full frame, 0.020 mm for APS-C Nikon / Sony, 0.019 mm for APS-C Canon, 0.015 mm for Micro Four Thirds, 0.011 mm for 1-inch, plus 0.038 and 0.044 mm for medium format. Focal length, aperture and focus distance default to 24 mm, f/8 and 3 m, switchable to feet.
Circle of confusion is a convention rather than a measurement. These values work out to roughly the sensor diagonal divided by 1,440, which assumes a modest enlargement viewed at a normal distance. Pixel-peep at 100% and your usable depth of field will be noticeably shallower than the table suggests. The comparison rows also run f/2.8 through f/22 whether or not your lens offers them, and diffraction is not modelled, so the gain at f/22 is overstated.
Focus at the hyperfocal distance shown and everything from half that distance to infinity falls within the acceptable-sharpness limits. At the default 24 mm, f/8, full frame, that means focusing about 2.42 m away for sharpness from roughly 1.21 m onward.
Once your focus distance reaches or exceeds the hyperfocal distance, the far limit is unbounded. The tool detects that H - (s - f) has dropped to zero or below and prints the infinity symbol rather than an implausibly large number.
The presets are 0.020 mm for Nikon and Sony APS-C and 0.019 mm for Canon APS-C, reflecting their slightly different sensor sizes. Smaller sensors take a smaller circle of confusion because the captured image must be enlarged more to reach the same print size.
The table shows depth of field still growing at f/22, but it does not model diffraction, which softens the entire frame at small apertures. On most modern lenses f/8 to f/11 is the practical limit before diffraction cancels out the extra depth.
No. Focusing at infinity throws away the near half of your available depth of field. Focus at the hyperfocal distance instead and you keep infinity acceptably sharp while gaining everything from half the hyperfocal distance forward, which the tool shows for you.
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