How to focus Nikon d90 camera in photography mode, manual focus and auto focus, is depth of field control, please explain in detail.

I remember that the D90 can't focus automatically in camera mode, so it can only focus manually. Manual focusing requires you to rotate the focusing ring, which requires more practice to master. Depth of field control depends on the change of focal length and aperture. Considering that SLR is very sensitive to the depth of field, it is recommended to shoot with a small aperture in order to ensure that it is not fake.

Let's talk about experience for your reference:

Experience of shooting video with SLR

Shooting video with SLR must have its advantages, and that alone is enough for me to get involved. So some people don't have to convince me, just chicken ribs, which are boring. I don't need to use it to make commercial movies, but I can use it to make my own movies without wasting money on its functions.

I once made a video recording cooking with a SLR, plus some experiences I saw in digitalrev before. Let me sum up my experience in shooting video with SLR. I'm a rookie, too, and it may not be correct or applicable to everyone. The most direct thing is to try it yourself. Of course, I want to share the discussion with you:

1. Try to use lenses with anti-shake function (Pentax can turn on the camera for anti-shake).

Although the anti-shake design is not aimed at video, this function is completely suitable for shooting video, especially in hand-held situations. It is best to close it on a tripod, but many anti-shake measures are counterproductive on a tripod. Some people will ask, what will happen besides holding hands and on a tripod? One possibility is to put it on a moving car to shoot a video. Maybe you put it on the pillow. If the road conditions are not good at this time, it should be said that anti-shake is still useful. With or without anti-shake, you can feel the great influence on the picture. It can overcome the biggest problem of shooting video to a great extent.

2. Tripod with video pan/tilt function

Many shots must be shot with a tripod. I think the effect of using a tripod is self-evident, so this need not be explained. What I want to say here is that it is very important to have a camera for shooting videos! Multi-directional combined motion mode, uniform damping and easy-to-master handle are the keys to ensure uniform and smooth lens movement.

3. Try to use a small aperture in many cases.

Although one of the advantages of SLR video shooting is its large aperture and blurred background. However, this influence is not necessary in all cases. In some cases where you find it difficult to grasp, you can record with a small aperture to ensure accurate focus, and you can also deal with unexpected situations (such as sudden appearance of objects, you need to continuously rotate the lens immediately), or objects that move faster (especially those that move back and forth relative to you).

4. Try to use manual focusing.

In most cases, manual focusing can ensure accuracy, and the more you use it, the more skilled you are. Manual focusing can also capture the effect of slowly focusing or slowly defocusing.

5. If appropriate, the actual distance of the focus on the lens can be used for scale display.

Combined with manual focusing and appropriate aperture range, sometimes the actual focusing distance scale (the value of m/ft) on some lenses can be used to estimate the focusing. This is difficult to use, because if you don't rotate the screen, you can't look at the screen and scale at the same time. But this is a very practical auxiliary tool. It's easier to have a rotating screen.

6. The zoom lens has advantages.

Zoom lenses can be used to shoot lenses with zoom. I think everyone knows this important point, and I don't need to say more. Generally speaking, video does not need such good lens imaging quality and such a huge aperture, so using zoom lens also saves a lot of effort to change lenses.