Traditional Culture Encyclopedia - Photography and portraiture - How is the background blur of SLR camera realized? Which blur effect is best, 30mm or 50mm or 85mm?

How is the background blur of SLR camera realized? Which blur effect is best, 30mm or 50mm or 85mm?

Blurred?

Need a large aperture theory. The larger the aperture, the better the effect.

Focus on focusing. It is suggested that manual focusing and autofocus may not work well or turn on macro mode.

I haven't successfully set the aperture to the maximum of 30 mm to shoot macro. .

50 is enough. The background is not too blurred to see clearly.

80 with a large aperture is perfect.

It is suggested that the M-file operator slowly adjust the parameters to take good photos, which is very emotional!

Attach a fuzzy diagram.

This is not a SLR. I took it with a Fuji telephoto lens.