Depth of Field for Portrait Photography
Portraits are the opposite of landscapes: you want shallow depth of field, placed so the eyes are sharp and the rest falls away. The numbers make it predictable.
How much DoF is actually right?
The classic portrait target is both eyes sharp — about 3–8 cm of depth of field at the eyes for a head-and-shoulders shot. Much less and one eye blurs; much more and the background starts competing with the subject.
Here's the real math (full frame, CoC 0.029 mm, subject at 2 m):
| Lens | Aperture | Total DoF at 2 m | Result |
|---|---|---|---|
| 50 mm | f/1.8 | ~16 cm | Good — safe for head-and-shoulders |
| 85 mm | f/1.8 | ~5.5 cm | Classic — both eyes sharp, hair softens |
| 85 mm | f/2.8 | ~9 cm | Forgiving group/candid choice |
| 135 mm | f/2 | ~2 cm | Very thin — focus on the near eye, recompose |
These come straight from the depth of field calculator — change the subject distance to 3 m and every number roughly doubles.
The three levers (and their limits)
- Focal length: 85–135 mm compresses perspective and magnifies background blur. 50 mm needs to be close — which distorts features at very short distances.
- Aperture: f/1.2–f/2 gives the thinnest DoF but the thinnest margin for focus error — at f/1.2 a 2 cm shift in the subject's pose can move their eyes out of the sharp zone.
- Subject-to-background distance: the most underrated lever. Move the subject 2 m from the background and even f/4 produces creamy separation; with the subject against a wall, no lens can save it.
Focus technique for thin DoF
- Focus on the near eye (single-point AF, eye-detection on mirrorless) — the near eye is what viewers lock onto.
- Shoot at the widest aperture that keeps both eyes sharp for the framing — check the DoF number, don't guess.
- Watch the ⅓–⅔ rule: about ⅓ of the DoF sits in front of the focus point, ⅔ behind — so focus slightly toward you if the far eye matters.
- If using a 135 mm at f/2, shoot a quick burst and pick the sharpest frame — a 2 cm DoF moves with the subject's sway.
APS-C and Micro 4/3 portraits
On APS-C, an 85 mm f/1.8 at 2 m gives ~4 cm of DoF — still perfect for portraits; the crop just changes your working distance for the same framing (step back to ~2.7 m for head-and-shoulders, which widens DoF to ~7 cm). On Micro 4/3, a 45 mm f/1.8 behaves like a 90 mm full-frame field of view with roughly the DoF of an f/3.6 full-frame lens — the format's famous "two-stop" penalty. Same framing, more DoF than full frame; you compensate with faster lenses or more background distance.
Related tools & guides
Depth of Field Calculator
Your exact near/far limits for any lens, distance, and camera.
Open →Flash Guide Number Calculator
Keep the aperture you want and still get correct flash exposure.
Open →Camera Sensor Sizes
Why format changes the "look" of the same lens.
Read →Portrait DoF FAQ
Why do my f/1.8 portraits have one eye sharp and the other soft?
At typical 85 mm f/1.8 portrait distances your total DoF is only ~5 cm — less than the distance between a subject's eyes when they turn their head. Solution: stop to f/2.8 (DoF ~9 cm) or ask for a slight profile angle so both eyes are in the same plane.
Does a 50 mm f/1.2 give the same blur as an 85 mm f/1.8?
At the same subject framing and distance-to-background, no — background blur scales mostly with focal length and subject-to-background distance. The 85 mm compresses and blurs more, which is why it's the classic portrait focal length.
Is background blur the same as depth of field?
Related but not identical. DoF is the sharp zone in front of/behind the subject; background blur is how strongly a background beyond the DoF falls off. A long lens can have both shallow DoF and heavy background blur; a fast wide lens has shallow DoF but mild background blur.