What else does the photo have except that it is out of focus?

In many cases, the reason why the photo image is blurred is "hand shock" when the photographer presses the shutter or "machine vibration" when the camera mirror rises. If you use a tripod, no matter how slow the shutter speed is, even if it is exposed for a long time, it can prevent the image from blurring caused by "jitter". However, it should be noted that when using a tripod, try to use cable release. Ignoring this point may still affect the clarity due to the vibration generated when the finger touches the shutter.

2. Use a high-speed shutter as much as possible.

When taking pictures with a hand-held camera, use a high-speed shutter as much as possible. For inexperienced photographers, when the shutter speed is set below 1/30s, the probability of taking photos is greater. Even a professional photographer can't guarantee 100% certainty when shooting with a low-speed shutter. Increasing the shutter speed will correspondingly increase the probability of clear photos. Of course, if you use a hand-held camera to increase the shutter speed, it will inevitably open a large aperture, thus losing the "large depth of field", but in order to ensure the clarity of the photo, it is a last resort to give up the depth of field.

3. Use the "best aperture" as much as possible.

There are different degrees of imaging errors in any lens, which will affect the imaging quality of the lens to varying degrees. Due to the different curvature of the spherical surface of the lens, the light can't focus on the same focus when passing through the center and edge of the lens because of the different refractive indexes, which leads to the decrease of definition. If you shoot with the maximum aperture of the lens, it will lead to the maximum exposure of lens aberration defects, which will lead to the decline of image clarity, while shooting with the minimum aperture of the lens will produce light diffraction and also lead to the decline of image clarity. In order to improve the sharpness reduction caused by aberration, the aperture is usually reduced to improve the imaging quality. Generally speaking, the best aperture of a lens is to reduce the maximum aperture of the lens by about 2~3 steps, and the photographer can compare the best aperture of a lens.

4. Use manual focusing as much as possible.

At present, most cameras have autofocus function. However, if the depth of field is extremely small, autofocus will often be inaccurate, especially if the subject is focused at close range. You should be especially careful when taking close-up portraits with a long focal length lens and a large aperture. If autofocus is used at this time, the "target" must be aimed at people's eyes. If you are not sure, you would rather give up autofocus and use manual focus. People don't want the ears or noses of the characters in the photos to be clear, while the vivid eyes are blurred.