How does SLR model photography capture the bright background and dark effect of the subject?

This goal can be achieved by means of equipment selection, light distribution and photographic parameters selection.

Equipment selection: choose a telephoto lens with a large aperture, such as a lens above 200mm, with an aperture of about F 2.8;

In terms of light distribution, the background does not need to be deliberately shaded, as long as there is no strong light to illuminate the background. The model can be illuminated by side backlight, and the side of the model can be illuminated by off-board flash or reflector.

Try to use a longer focal length, such as more than 200mm, and a larger aperture as much as possible, which will have a little impact on the image quality, but you can get the background effect you want.

It is necessary to use manual exposure.

Later, adjust the brightness and contrast moderately.