景深计算器
计算任意镜头、光圈和相机传感器的景深（DOF）、近景和远景边界以及超焦距。输入焦距、光圈 f 值和对焦距离，即时查看照片的完整清晰范围。
H = f² / (N × c) + f | Near = s(H−f) / (H+s−2f) | Far = s(H−f) / (H−s)
Related Calculators
常见问题
摄影中的景深是什么？
景深（DOF）是照片中看起来清晰的距离范围。当你对准特定距离对焦时，该点前后略有偏移的物体也会显得清晰。这个清晰区域的大小就是景深。浅景深意味着只有一薄层平面是清晰的（常见于人像摄影），而深景深意味着大范围都清晰（常见于风景摄影）。
光圈如何影响景深？
光圈对景深的影响最为显著。大光圈（小光圈数值如 f/1.4 或 f/2.8）产生浅景深，背景模糊（虚化）效果强烈。小光圈（大光圈数值如 f/11 或 f/16）产生深景深，近处和远处的物体都清晰。光圈每缩小一档（如从 f/2.8 到 f/4），景深大约翻倍。
什么是超焦距？
超焦距是使无穷远处物体仍然清晰的最近对焦距离。当你对准超焦距对焦时，从超焦距一半到无穷远的所有物体都在焦点内——为给定的光圈和焦距提供最大可能的景深。它是风景摄影的最佳对焦点。
焦距如何影响景深？
在相同对焦距离下，较长焦距（长焦镜头）比较短焦距（广角镜头）产生更浅的景深。在相同距离对焦时，200mm f/5.6 的镜头比 24mm f/5.6 的镜头景深浅得多。但如果调整对焦距离使主体在画面中的大小相同，差异会不那么明显。
传感器尺寸会影响景深吗？
是的，传感器尺寸通过计算中使用的弥散圆（CoC）值间接影响景深。全画幅相机使用 CoC = 0.030mm，APS-C 约 0.020mm，微型四三约 0.015mm。在相同焦距、光圈和对焦距离下，由于弥散圆更大，全画幅传感器提供更多景深。但为了捕捉相同取景效果，较大传感器上需要更长的焦距，这会抵消这种效果。
什么是弥散圆？
弥散圆（CoC）是在标准观看距离（通常 25cm）处观看照片时，人眼感觉为清晰点的最大模糊斑点尺寸。它决定了景深计算中使用的清晰度阈值。全画幅的标准值为 0.030mm，APS-C 为 0.020mm，微型四三为 0.015mm。CoC 值越小，计算出的景深越浅。
如何在风景摄影中利用超焦距？
最大化风景摄影景深的方法：(1) 在计算器中输入镜头焦距和所选光圈；(2) 记录显示的超焦距；(3) 将焦点设在该距离处（使用镜头的距离刻度或对焦峰值）；(4) 从超焦距一半到无穷远的所有物体都在焦点内。例如，全画幅上 f/8 的 24mm 镜头超焦距约为 2.4m——对准该距离对焦，从 1.2m 到无穷远的所有物体都清晰。
为什么计算器中景深会显示为无穷远？
当你的对焦距离等于或超过超焦距时，景深的远限延伸至无穷远。这意味着在近限之外的所有物体一直到地平线都会显得清晰。这种情况常见于小光圈（高光圈数值）的广角镜头（如 f/11 或 f/16），或拍摄远处被摄体时。计算器在这种情况下会显示「∞」作为远限和总景深。
What is Depth of Field?
Depth of field (DOF) is the range of distances in a photograph that appear acceptably sharp. When you focus your camera at a specific distance, objects close to that point — both in front and behind — will also appear sharp, while objects farther from the focus point will be blurred.
DOF is not a binary sharp/blurry boundary. Rather, sharpness gradually decreases as distance from the focus point increases. The “acceptable” sharpness threshold is defined by the circle of confusion (CoC) — the maximum size of a blur spot that the human eye perceives as a point when viewing a print at a standard viewing distance.
Three main factors control depth of field: aperture (f-stop), focal length, and focus distance. Sensor size indirectly affects DOF through the circle of confusion value.
Depth of Field Formula
The standard DOF calculation uses the hyperfocal distance as an intermediate value. Here are the exact formulas used by this calculator:
Hyperfocal Distance (H):
H = f² / (N × c) + f
where f = focal length (mm), N = f-stop number, c = circle of confusion (mm)
Near Limit:
Dnear= s(H − f) / (H + s − 2f)
Far Limit:
Dfar= s(H − f) / (H − s) [∞ when s ≥ H]
Total Depth of Field:
DOF = Dfar − Dnear
The variable s is the focus distance in millimeters. All units must be consistent — the calculator converts meters to millimeters internally and returns results in meters for readability.
Aperture and Depth of Field Relationship
Aperture (expressed as an f-stop or f-number) has the most dramatic effect on depth of field. A wider aperture (smaller f-number like f/1.4) produces a shallower DOF, while a narrower aperture (larger f-number like f/16) produces a deeper DOF.
| Aperture | DOF Effect | Common Use |
|---|---|---|
| f/1.4 – f/2.8 | Very shallow | Portrait, low-light, artistic blur |
| f/4 – f/5.6 | Moderate | General photography, street |
| f/8 – f/11 | Deep | Landscape, architecture, group shots |
| f/16 – f/22 | Very deep | Macro, technical photography |
Note that very small apertures (f/16 and beyond) introduce diffraction, which can reduce sharpness across the entire frame. Most lenses perform best between f/5.6 and f/11 for overall sharpness.
Hyperfocal Distance
The hyperfocal distanceis the closest focus distance at which objects at infinity are still acceptably sharp. It is the “sweet spot” for landscape and street photography where you want everything from a near point to infinity in focus.
When you focus at the hyperfocal distance:
- Everything from half the hyperfocal distance to infinity is in focus.
- The far limit extends to infinity.
- You achieve the maximum possible depth of field for a given aperture and focal length.
Example: 24mm lens at f/8 (full frame):
H = 24² / (8 × 0.030) + 24
H = 576 / 0.24 + 24
H = 2400 + 24 = 2424 mm ≈ 2.42 m
Focus at 2.42 m → sharp from 1.21 m to ∞
A shorter focal length or smaller aperture results in a shorter hyperfocal distance, making it easier to get everything sharp. This is why wide-angle lenses are preferred for landscape photography.
How Sensor Size Affects Depth of Field
Sensor size affects DOF indirectly through the circle of confusion (CoC)value. A larger sensor has a larger maximum acceptable blur spot, which paradoxically results in a shallower depth of field at the same field of view and aperture — because a larger sensor requires a longer focal length to achieve the same framing.
| Sensor Format | Typical CoC | Crop Factor | DOF vs Full Frame |
|---|---|---|---|
| Full Frame (35mm) | 0.030 mm | 1.0× | Reference |
| APS-C (Canon/Nikon) | 0.020 mm | 1.5–1.6× | ~1.5× deeper |
| Micro 4/3 | 0.015 mm | 2.0× | ~2× deeper |
When comparing cameras, use the equivalent aperture (multiply f-stop by crop factor) to get the same DOF effect. For example, f/2.8 on a Micro 4/3 camera gives the same DOF as approximately f/5.6 on a full-frame camera with the same framing.
Depth of Field Calculation Examples
Example 1: Portrait Photography (85mm f/1.8 at 2m)
A portrait photographer uses an 85mm lens at f/1.8 focused at 2 meters on a full-frame camera.
H = 85² / (1.8 × 0.030) + 85 = 7225 / 0.054 + 85 ≈ 133,796 mm ≈ 133.8 m
Near = 2000(133796 − 85) / (133796 + 2000 − 170) ≈ 1972 mm ≈ 1.97 m
Far = 2000(133796 − 85) / (133796 − 2000) ≈ 2029 mm ≈ 2.03 m
Total DOF ≈ 6 cm — very shallow, ideal for subject separation
Example 2: Landscape Photography (24mm f/8 at hyperfocal)
A landscape photographer uses a 24mm lens at f/8 on a full-frame camera, focused at the hyperfocal distance of approximately 2.4 meters.
H ≈ 2424 mm ≈ 2.42 m
Near ≈ H/2 = 1.21 m
Far = ∞
Everything from 1.21 m to infinity is in sharp focus.
Example 3: APS-C vs Full Frame at Same Settings
Compare a 50mm f/2.8 at 3m on full frame vs APS-C:
Full Frame (CoC=0.030): Near ≈ 2.77 m, Far ≈ 3.27 m, DOF ≈ 50 cm
APS-C (CoC=0.020): Near ≈ 2.84 m, Far ≈ 3.19 m, DOF ≈ 35 cm
APS-C gives ~30% shallower DOF at identical settings (but frames differently).