To maximize background blur in-camera, aim for the shallowest depth of field possible. The main factors are:

1. Move closer to your subject — this has a very strong effect.
2. Use a longer focal length — telephoto lenses usually blur the background more.
3. Use a wider aperture — choose the lowest f-number your lens allows (for example, f/2.8 instead of f/8).

A practical setup is: get close to the subject, zoom in or use a longer lens, and shoot wide open.

Because a wide aperture lets in more light, you may need to:

• use a faster shutter speed,
• lower ISO,
• or add a neutral density filter in bright conditions.

Also, the look of the background matters. Even without extreme blur, a plain or distant background (such as sky, fog, mist, or a simple backdrop) will make the subject stand out more. You can also light or expose the scene so the background is darker and less distracting.

So the best recipe is: close subject + long lens + wide aperture + simple/distant background.