The reason why the subject is virtual and the background is real when shooting.

This is a typical out-of-focus phenomenon, which is easily caused by the following situations:

1。 The focal length of the lens is too short.

The focal length is the moving distance of the internal lens group from the nearest distance to infinity. Short focal length can improve the focusing speed of the lens, but it is difficult to focus accurately, which is suitable for lenses with small aperture or focal length. Long focal length can improve the focusing accuracy, but the focusing speed is slow, which is suitable for large aperture or telephoto lens. Therefore, it is understandable that some lenses are unreasonable in design due to cost considerations, and the focus is slow or out of focus.

2。 The proportion of the subject in the painting is too small.

Because the subject is too small, the focus confuses the subject with the background, and finally focuses on the relatively large background.

3。 The object is too close to the background or too far from the camera.

The principle of SLR camera phase focusing is to capture the focus with a small sensor, and the fineness is determined by the sensor pixels. The distance between pixels causes the focus to be divided, while the focal length of the lens at a distance of 3 meters is relatively short, which makes the focus division very long. At this distance, the subject is easily out of focus, and it is often impossible to focus accurately. If the subject is too close to the background, it is easy to be in the same focal length, so the focus will be mainly on the background.

4。 Ambient lighting is too low.

The phase focusing of SLR needs a lot of ambient light. When the light is insufficient, the focus cannot be completed or the focus is not accurate.

Based on the above reasons, photographers will use corresponding techniques to improve the problem when shooting, such as using small aperture, manual focusing, wide-angle end, artificial fill light and so on.