Depth of Field
Written by Abin Alex and Anu Joseph.
Abstract
Depth of field is the band of distances in a picture that looks acceptably sharp. It becomes shallower with a wider aperture, a closer subject, a longer lens, or a larger sensor at the same framing, and deeper in the opposite cases. This guide explains the circle of confusion, which makes acceptable sharpness a choice, the plane of focus with its near and far limits, and the types of depth of field. It also shows how cinematographers use depth of field to decide how much of each shot the audience sees sharply. It is written for photographers and cinematographers.
Keywords: depth of field; circle of confusion; aperture; focal length; subject distance
- What is depth of field, and what does it do?
- What is the circle of confusion, and why is "acceptably sharp" a choice?
- What are the plane of focus, the near limit and the far limit?
- What are the types of depth of field?
- What factors affect depth of field?
- How does aperture change depth of field?
- How does focal length change depth of field?
- How does subject distance change depth of field?
- Does sensor size change depth of field?
- Is the sharp zone really one third in front and two thirds behind?
- What is hyperfocal distance, and how do you use it?
- How do you calculate depth of field?
- How do photographers and cinematographers control depth of field?
- How much depth of field does each kind of photography need?
What is depth of field, and what does it do?
Short answer. Depth of field is the band of distances in a picture that looks acceptably sharp. Only one distance is in perfect focus. Things slightly nearer or farther still look sharp enough, and that whole zone is the depth of field.
- Sharpness falls off gradually, not suddenly, so the edges of the zone depend on how strict "acceptably sharp" is.
- It is a range of distances in the scene, measured in metres or centimetres.
- A shallow depth of field isolates the subject. A deep depth of field keeps near and far sharp together.
- Four things control it: aperture, subject distance, focal length and sensor size. The next chapters take them one by one.
A lens can focus exactly on one distance. A point nearer or farther than that distance is recorded as a small disc, not a point. If the disc is small enough that the eye cannot tell it from a point, that detail looks sharp. Depth of field is the stretch of distances for which this is true.
Cham tipDepth of field is how much of the picture looks sharp. Focus on the subject's eye first.
Cham taskTake one portrait with a sharp background and one with a blurred background. Write which settings you changed.
Check yourself: Is depth of field measured on the sensor or in the scene?
In the scene. It is a range of distances in front of the lens. The matching tolerance on the sensor side is called depth of focus.
What is the circle of confusion, and why is "acceptably sharp" a choice?
Short answer. The circle of confusion is the largest blur disc that can still pass for a sharp point, and depth of field is calculated from it. How sharp counts as sharp enough depends on the print size and the viewing distance, so the circle is a chosen limit, not a law of nature.
- A point that is out of focus is recorded as a disc. That disc is the circle of confusion.
- For full frame the usual limit is the sensor diagonal divided by 1500, about 0.03 mm. It assumes a small print, about 12 by 18 cm, seen from 25 cm (Nasse, 2010).
- A stricter limit, the diagonal divided by 3000, is used when the picture will be enlarged a lot (Nasse, 2010).
- Cinema tables use 0.025 mm for 35 mm motion picture film and 0.015 mm for 16 mm (ARRI and ZEISS, n.d.; Cooke Optics, n.d.; DOFMaster, n.d.).
- Because the limit is chosen, calculators and tables give good estimates, not exact edges.
Cham tipSharpness depends on how large and how close the picture is viewed. A photo that looks sharp on a phone may not on a large print.
Cham taskView one photo on your phone, on a laptop and at 100 percent. Note where it stops looking sharp.
Check yourself: Two people calculate depth of field for the same lens and distance but get different answers. Give one reason.
They may have used different circle of confusion limits, for example the diagonal divided by 1500 and the diagonal divided by 3000.
What are the plane of focus, the near limit and the far limit?
Short answer. The plane of focus is the one flat distance, parallel to the sensor, that is perfectly sharp. The near limit and the far limit are the closest and farthest distances that still look acceptably sharp. Depth of field is the gap between the two.
- Near limit and far limit are measured from the camera. The depth of field is the far limit minus the near limit.
- In theory the plane of focus is flat and parallel to the sensor. It is not a curved shell around the camera.
- Distance is measured from the sensor plane, not from the front of the lens. Many cameras mark the sensor plane with a small symbol on the body.
- The zone is usually deeper behind the plane of focus than in front of it. Question 10 shows by how much.
Cham tipOnly one distance is exactly in focus. The sharp zone around it is the depth of field.
Cham taskPlace three objects at 1 m, 2 m and 4 m. Focus on the middle one and note which others look sharp.
Check yourself: A subject is at 3 m. The near limit is 2.73 m and the far limit is 3.33 m. What is the depth of field?
3.33 minus 2.73, which is 0.60 m.
What are the types of depth of field?
Short answer. Depth of field is called shallow or deep. A shallow depth of field keeps only a thin zone sharp, and a deep one keeps most of the scene sharp. Photographers call the first selective focus, and cinematographers call the second deep focus.
- Shallow depth of field comes from a wide aperture, a close subject and a long lens. Deep depth of field comes from a narrow aperture, a far subject and a wide lens.
- There is no fixed line between shallow and deep. The words describe the look of the picture, not a number.
- Pan focus is another name for a very deep depth of field, where nearly everything is sharp.
- Depth of field is measured in the scene. Depth of focus is the small range of sensor positions that keeps the image sharp. It depends on the f-number and the circle of confusion, about twice their product (Nasse, 2010).
- Bokeh is not a type of depth of field. It is the look of the blur outside the sharp zone.
| Type | How it is made | Typical use |
|---|---|---|
| Shallow (selective focus) | Wide aperture, close subject, long lens | Portraits, macro, close-ups, rack focus |
| Medium | Middle apertures, medium distance | Interviews, two-shots, general work |
| Deep (deep focus, pan focus) | Narrow aperture, far subject, wide lens | Landscape, architecture, deep staging in film |
Table 1. Shallow, medium and deep depth of field.
Cham tipDecide first whether the picture needs shallow or deep depth of field, then choose the settings.
Cham taskShoot one scene with shallow depth of field and one with deep depth of field. Name each type.
Check yourself: A friend says bokeh and shallow depth of field are the same thing. Are they?
No. Depth of field is how much of the picture is sharp. Bokeh is the quality of the blur outside that zone.
What factors affect depth of field?
Short answer. Four things change depth of field: the aperture, the distance to the subject, the focal length and the sensor size. A wider aperture, a closer subject, a longer lens at the same distance and a larger sensor at the same framing each make it shallower.
- Aperture: a wider opening gives a shallower depth of field.
- Subject distance: a closer subject gives a shallower depth of field.
- Focal length: a longer lens gives a shallower depth of field at the same distance. At the same framing the difference almost disappears.
- Sensor size: at the same framing and f-number, a larger sensor gives a shallower depth of field.
- The circle of confusion you accept, which follows print size and viewing distance, also moves the limits.
- ISO and shutter speed do not change depth of field.
| Change | Effect on depth of field | See question |
|---|---|---|
| Wider aperture (smaller f-number) | Shallower | 6 |
| Closer subject | Shallower | 8 |
| Longer lens, same distance | Shallower | 7 |
| Longer lens, same framing | Almost unchanged | 7 |
| Larger sensor, same framing and f-number | Shallower | 9 |
| Tighter circle of confusion limit | Shallower | 2 |
Table 2. What each factor does.
Cham tipFour things control depth of field: aperture, focal length, subject distance and sensor size. Change one at a time to learn each.
Cham taskShoot the same subject four times, changing only one factor each time. Write what each did.
Check yourself: Which two changes make depth of field deeper: moving closer or stepping back, opening up or stopping down?
Stepping back and stopping down.
How does aperture change depth of field?
Short answer. Closing the aperture (a larger f-number) deepens the depth of field, and opening it (a smaller f-number) makes it shallower. With distance and focal length fixed, the total depth of field grows roughly in step with the f-number.
- Each full stop multiplies the f-number by about 1.4, and the depth of field by about the same amount. Two stops roughly double it.
- Changing the aperture also changes the exposure, so balance it with shutter speed or ISO.
- Very small apertures bring diffraction, which softens the whole picture. See is the smallest aperture sharpest.
- Calculations use the f-number. Cine tables list T-stops, which differ from the f-number by a third of a stop or less (ARRI and ZEISS, n.d.; Cooke Optics, n.d.).
| f-number | Near limit | Far limit | Total |
|---|---|---|---|
| f/1.4 | 2.86 m | 3.16 m | 0.30 m |
| f/2 | 2.80 m | 3.23 m | 0.43 m |
| f/2.8 | 2.73 m | 3.33 m | 0.60 m |
| f/4 | 2.63 m | 3.50 m | 0.87 m |
| f/5.6 | 2.50 m | 3.74 m | 1.24 m |
| f/8 | 2.34 m | 4.19 m | 1.85 m |
| f/11 | 2.16 m | 4.91 m | 2.75 m |
| f/16 | 1.92 m | 6.92 m | 5.00 m |
Table 3. Calculated with the formulas in question 12.
Cham tipStop down one stop at a time and watch the background sharpen.
Cham taskShoot a subject at f/2, f/4, f/8 and f/16 from the same spot. Compare the background sharpness.
Check yourself: Depth of field is 0.87 m at f/4 in this table. About what is it at f/8?
About 1.85 m, roughly double, because f/8 is two stops from f/4.
How does focal length change depth of field?
Short answer. At the same distance and f-number, a longer lens gives a shallower depth of field. If you step back to keep the subject the same size, though, the depth of field is almost the same at any focal length. The longer lens simply makes the background look more blurred.
- At the same distance, depth of field falls roughly with the square of the focal length.
- At the same framing, it depends mostly on the magnification of the subject, not on the focal length.
- A longer lens enlarges the distant background, so the blur there looks larger and the background looks softer.
- So "long lenses have less depth of field" is true at a fixed distance and misleading at a fixed framing.
Cham tipFrom the same spot, a longer lens gives a shallower depth of field.
Cham taskShoot a subject from the same spot at 24 mm and at 70 mm with the same f-number. Compare.
Check yourself: A face fills the frame at 50 mm f/4 from 3 m, and again at 135 mm f/4 from 8.1 m. Which has the deeper depth of field?
They are almost equal, 0.87 m and 0.85 m. The 135 mm lens blurs the background more, but the sharp zone around the face is nearly the same.
How does subject distance change depth of field?
Short answer. The closer the subject, the shallower the depth of field. It grows roughly with the square of the focus distance, so doubling the distance gives about four times as much.
- This is the strongest control you have. Stepping back from 1 m to 2 m takes a 50 mm lens at f/2.8 from about 6 cm to about 26 cm (Nasse, 2010).
- At life size (1:1 reproduction) and f/8 the total depth is only about 1 mm. Close-up work needs narrow apertures or focus stacking (Ray, 2002).
- The square rule is an approximation. It weakens as the focus distance approaches the hyperfocal distance.
- Moving the camera also changes perspective, not only depth of field.
Cham tipMove closer to make depth of field shallower. Step back to make it deeper.
Cham taskPhotograph a small object at 30 cm and at 1 m with the same aperture. Compare how much is sharp.
Check yourself: You double the distance to the subject and change nothing else. About how many times deeper does depth of field become?
About four times.
Does sensor size change depth of field?
Short answer. Yes. With the same framing and the same f-number, a larger sensor gives a shallower depth of field and a smaller one gives a deeper depth of field. Phone sensors are tiny, which is why phone pictures look sharp from front to back.
- A smaller sensor needs a shorter lens, or a longer distance, to frame the same scene. Both give more depth of field.
- The accepted circle of confusion is also smaller on a smaller sensor, but the first effect wins.
- Equivalent f-numbers scale with the sensor size. On a 1.5 crop sensor, f/2 gives roughly the depth of field of f/3 on full frame.
- Blur in phone portrait mode is added by software, not made by a wide aperture.
| Sensor | Crop factor | f/2.8 behaves like, in depth of field, on full frame |
|---|---|---|
| Full frame | 1.0 | f/2.8 |
| APS-C (Nikon, Sony) | 1.5 | about f/4.2 |
| APS-C (Canon) | 1.6 | about f/4.5 |
| Micro Four Thirds | 2.0 | f/5.6 |
Table 4. Equivalent f-numbers for the same framing. Multiply the f-number by the crop factor.
Cham tipA bigger sensor gives a shallower depth of field at the same framing and f-number.
Cham taskLook up the crop factor of your sensor and note how it compares with full frame.
Check yourself: A crop-sensor camera (crop factor 1.5) and a full-frame camera frame the same subject at f/2.8. Which has the deeper depth of field?
The crop-sensor camera, which behaves like about f/4.2 on full frame.
Is the sharp zone really one third in front and two thirds behind?
Short answer. No. That rule holds only at one focus distance. When you focus close, the sharp zone is almost equal in front of and behind the subject. The split reaches one third to two thirds when you focus at about one third of the hyperfocal distance, and farther out more and more of the zone lies behind the subject.
- The shape of the zone changes with the focus distance, so no single ratio is correct for every shot.
- In close-ups and macro the zone is nearly symmetric.
- At one third of the hyperfocal distance the far limit is twice as far from the subject as the near limit (Nasse, 2010).
- When you focus at the hyperfocal distance, the far limit is infinity and the near limit is half the hyperfocal distance.
| Focus distance as a share of the hyperfocal distance | Depth behind compared with depth in front |
|---|---|
| 5% | 1.1 to 1 (almost equal) |
| 10% | 1.2 to 1 |
| 33% (one third) | 2 to 1 (the "one third, two thirds" case) |
| 50% | 3 to 1 |
| 75% | 7 to 1 |
| 90% | 19 to 1 |
Table 5. How the zone shifts behind the subject as the focus distance grows. Values follow from the formulas in question 12 when the focus distance is much larger than the focal length.
Cham tipOne third in front and two thirds behind is a rule of thumb. For close subjects the zone is nearly half and half.
Cham taskFocus on a subject 1 m away. Mark where sharpness starts and ends in front and behind.
Check yourself: At which focus distance is the sharp zone one third in front and two thirds behind?
At about one third of the hyperfocal distance. At other distances the split is different.
What is hyperfocal distance, and how do you use it?
Short answer. The hyperfocal distance is the closest focus distance at which the far limit of sharpness reaches infinity. Focus there, and everything from half that distance to infinity looks acceptably sharp.
- Formula: H = f² ÷ (N × c) + f, where f is the focal length, N the f-number and c the circle of confusion (Nasse, 2010; Ray, 2002).
- A shorter lens and a smaller aperture give a shorter hyperfocal distance.
- With focus at H, the near limit is H ÷ 2.
- The value depends on the chosen circle of confusion, so for large prints use a longer distance than the table shows.
- Cine depth of field tables print the hyperfocal distance for each stop (Cooke Optics, n.d.).
| Lens (full frame) | f/8 | f/11 | f/16 |
|---|---|---|---|
| 24 mm | 2.42 m | 1.77 m | 1.22 m |
| 35 mm | 5.14 m | 3.75 m | 2.59 m |
| 50 mm | 10.47 m | 7.63 m | 5.26 m |
Table 6. Hyperfocal distance H for circle of confusion 0.03 mm. The near limit is half of each value.
Cham tipFocus at the hyperfocal distance for landscapes so that everything from half that distance to infinity is acceptably sharp.
Cham taskLook up the hyperfocal distance for your lens at f/8 in a free app. Shoot a landscape focused there.
Check yourself: A 35 mm lens at f/8 on full frame has a hyperfocal distance of about 5.1 m. If you focus there, what is the near limit?
About 2.6 m, which is half of 5.1 m. Everything from there to infinity looks acceptably sharp.
How do you calculate depth of field?
Short answer. First find the hyperfocal distance, H = f² ÷ (N × c) + f. Then the near limit is s × (H − f) ÷ (H + s − 2f) and the far limit is s × (H − f) ÷ (H − s), where s is the focus distance. Use the same units throughout, usually millimetres.
- f is the focal length, N the f-number, s the focus distance and c the circle of confusion.
- The far limit is infinity when s is equal to or larger than H.
- When s is much smaller than H, the total depth of field is about 2 × N × c × s² ÷ f² (Ray, 2002).
- Use the f-number in the formulas. Cine tables list T-stops for convenience.
| Lens (Super 35, c = 0.025 mm) | Focus | Near limit | Far limit | Total |
|---|---|---|---|---|
| 35 mm at f/2.8 | 2.0 m | 1.80 m | 2.25 m | 0.46 m |
| 35 mm at f/5.6 | 2.0 m | 1.63 m | 2.58 m | 0.95 m |
| 50 mm at f/2 | 1.5 m | 1.46 m | 1.55 m | 0.09 m |
| 85 mm at f/2 | 2.5 m | 2.46 m | 2.54 m | 0.08 m |
| 25 mm at f/4 | 3.0 m | 2.03 m | 5.73 m | 3.69 m |
Table 7. Cinema examples calculated with the same formulas. Manufacturer tables are printed against T-stops, so real values differ slightly.
Cham tipUse a free depth of field calculator instead of working out the formula. Enter lens, aperture, distance and sensor.
Cham taskCalculate the near and far limits at 50 mm, 3 m, f/2.8 and again at f/8. Note the difference.
Check yourself: Use the approximation 2 × N × c × s² ÷ f² for a 50 mm lens at f/4 focused at 2 m, with c = 0.03 mm. What is the total depth of field?
2 × 4 × 0.03 × 2000² ÷ 50² is about 384 mm, so roughly 0.38 m.
How do photographers and cinematographers control depth of field?
Short answer. For a shallower depth of field, open the aperture, move closer and use a longer lens. For a deeper one, close the aperture, step back and use a wider lens. In bright light, a neutral density filter lets you keep the wide aperture.
- Choose the look first, then set the exposure around it with shutter speed, ISO, light or a neutral density filter.
- On many cameras a depth of field preview button closes the lens to the working aperture, so you can judge the zone in the viewfinder.
- More light lets you close the stop. Toland lit the sets of Citizen Kane strongly so he could shoot at f/8 and narrower (Toland, 1941).
- A rack focus moves the sharp plane from one subject to another during a shot. It needs a shallow depth of field to be visible.
- In stills, aperture priority mode is the quickest way to set the aperture. See how do I set the aperture on my camera.
| Goal | Aperture | Distance | Lens |
|---|---|---|---|
| Blur the background | Wider (f/1.4 to f/2.8) | Closer | Longer |
| Keep everything sharp | Narrower (f/8 to f/16) | Farther | Wider |
| Landscape, near to far | About f/8 to f/11 | Hyperfocal | Wide |
| Isolate one face on screen | Wide stop | Close | Long |
| Stage action in several planes | Narrow stop, more light | Medium | Wide |
Table 8. Quick settings for common goals.
Cham tipControl depth of field in this order: aperture, then subject distance, then focal length.
Cham taskPlan one shot where only the eyes are sharp and one where the whole scene is sharp. Write the settings for each.
Check yourself: It is a sunny day and you want a blurred background at f/2, but the camera cannot use a fast enough shutter. What fixes this?
A neutral density filter, which cuts the light so the wide aperture can stay.
How much depth of field does each kind of photography need?
Short answer. Choose the depth of field from what must be sharp. A shallow depth of field isolates the subject, and a deep one keeps the whole scene sharp. The distance to the subject matters as much as the aperture. Treat every line below as a starting point.
- Birds. The bird is far away, so the depth is already thin. Use f/5.6 to f/8 on a long lens to keep the whole bird sharp.
- Animals and pets. Shallow, with the nearer eye sharp. Use f/2.8 to f/4. On a face close to the lens, the nose can fall out of focus.
- Reptiles. Close shooting makes the depth thin. Use f/8 so the head and the body are both sharp.
- Insects and macro. The depth is only millimetres at life size. Use focus stacking, because closing the aperture too far softens the picture.
- Portraits. Shallow, f/1.8 to f/2.8, with focus on the nearer eye. Step back and zoom in for a softer background.
- Fashion. Shallow for details and mood. Deeper for full-length frames, so the whole outfit is sharp.
- Wedding and events. Shallow for rings and couple portraits. f/5.6 to f/8 for groups, so every face is sharp.
- Product. Deep, so the whole product is sharp. Use f/8 to f/11, and stack frames if you need more.
- Automotive. Deep for the whole car. Shallow for a badge or a headlight detail.
- Photojournalism. Deep enough to tell the story inside the frame. Use f/5.6 to f/8 with zone focus.
- Sports and action. Shallow isolates the athlete, but the margin for focusing errors is small.
- Landscape. Deep. Focus at the hyperfocal distance with f/8 to f/11.
- Street and documentary. Deep. Set f/8 and focus at the hyperfocal distance, then everything from half that distance to infinity is sharp.
- Night and astro. Focus on a bright star or at infinity. A wide lens gives deep focus.
- Cinema. Part of the look. Shallow isolates a face, and deep lets several actors in different planes hold attention.
Questions beginners ask
What is depth of field in simple words?
It is how much of the picture, from near to far, looks sharp. Only one distance is perfectly in focus. Things slightly before and behind it also look sharp enough.
Are bokeh and depth of field the same?
No. Depth of field is how much is sharp. Bokeh is the look of the blur outside it, such as how smooth it is and the shape of the out-of-focus highlights.
Does a longer lens always give a shallower depth of field?
At the same distance, yes. If you step back to keep the subject the same size, the depth of field stays almost the same. The longer lens only makes the background look more blurred.
Why does portrait mode on a phone blur the background?
Phone sensors are small, so the real depth of field is deep. Portrait mode adds the blur by software.
What does the depth of field preview button do?
On cameras that have it, it closes the lens to the aperture you chose, so you can see the depth of field in the viewfinder before shooting. The viewfinder normally shows the picture at the widest aperture.
References
- ARRI and ZEISS. (n.d.) Master Primes: Depth-of-field Tables. afcinema.com/IMG/pdf/8/c/3/depth-of-field-tables-arri-zeiss-master-prime-lenses.pdf
- Cooke Optics. (n.d.) Cooke APrime Lenses Depth of Field Tables. cookeoptics.com/wp-content/uploads/2021/11/Anamorphic-i-DoF-Tables_20161010.pdf
- DOFMaster. (n.d.) Depth of Field Calculations for Cinematography, which cites the 1986 edition of the American Cinematographer Manual for circle of confusion values of 0.025 mm (35 mm) and 0.015 mm (16 mm). dofmaster.com/cinematography.html
- Nasse, H.H. (2010) Depth of Field and Bokeh. Camera Lens News no. 35. Oberkochen: Carl Zeiss AG, Camera Lens Division. lenspire.zeiss.com/photo/app/uploads/2018/02/cln35_en_web_special_bokeh.pdf
- Ray, S.F. (2002) Applied Photographic Optics, 3rd edn. Oxford: Focal Press. See the entries on depth of field and depth of focus.
- Toland, G. (1941) “Realism for Citizen Kane”, American Cinematographer, February 1941. theasc.com/article/realism-for-citizen-kane
How to cite this guide. Alex, A., & Joseph, A. (2026). Depth of field: A guide for photographers and cinematographers. Creative Hut Academy. https://creativehut.org/library/what-is-depth-of-field/
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