What aperture works best for portraits, and how does it affect background blur and depth of field?

There isn’t one “portrait aperture” — it depends on your intent.

If you want strong subject isolation and a soft, blurred background, use a wide aperture such as f/2.8 or wider. This works well when the background is distracting or unimportant. The tradeoff is shallower depth of field, so at very wide settings like f/1.4, parts of a face can fall out of focus, especially in tight headshots.

For many portraits, a practical middle ground is about f/2.8 to f/5.6. That usually keeps the person sharp while still softening the background.

If the background is important to the story — for example, a dramatic landscape, clouds, or environmental context — stop down to around f/8 or higher so more of the scene stays in focus.

Lens choice and distance matter too: longer lenses and tighter framing often look great for portraits, but depth of field can get very thin. Some photographers find headshots with fast primes too shallow wide open, and prefer around f/2.8 to f/3.5 for more reliable facial sharpness.

So the best aperture is the one that matches your creative goal: isolate the subject, or include more of the environment.