The autofocus method of the D908i

Just press it all the time, start to focus, and after it turns into a green frame, it will automatically take a picture in a second or two. It's more convenient.

Ranging. Conventional cameras use a method similar to visual ranging to achieve autofocus, the camera emits a kind of infrared (or other rays), determines the distance of the subject according to the reflection of the subject, and then adjusts the lens combination according to the measured results to achieve autofocus. This method of autofocus – direct, fast, easy to implement, and low cost – but sometimes it can be wrong (autofocus is not possible when there is something else between the camera and the subject, such as glass, or in low light), and is not very accurate, and is generally not used in today's high-end cameras.

Because the camera actively emits rays, it is called active, and because it is actually only a distance measurement, and does not judge whether it is correctly focused through the actual imaging of the lens, it is also called non-TTL type.

Compared with active autofocus, this focusing method later developed passive autofocus, that is, judging whether it is correctly focused according to the actual imaging of the lens, and the basis for judging is generally contrast detection, and the specific principle is quite complex. Because this method is achieved by lens imaging, it is called TTL autofocus. Because this autofocus method is based on lens imaging, it has high focusing accuracy and a low error rate, but it is technically complex, slower (except for advanced autofocus lenses with ultrasonic motors), and high cost.

The method of manual focusing of the D90 is:

1. Use the Menu button to enter the personal settings menu (pencil icon), select A (autofocus) to enter A1 "AF Area Mode", and select "Single Point Focus". Press OK to confirm.

2. There is a locking switch under the arrow key on the back of the fuselage, and there is an L gear and a solid key to rent the annihilation dot gear, which is placed in the shape of the dot gear (unlocked state).

3. Use the arrow keys to move the position of the focus frame displayed in thick black (a total of 11 points can be selected).

Autofocus is performed according to the determined focus point, and when the shutter is pressed halfway, the focus is locked, at which point the camera can be moved to reframe the shot (the shutter state should be maintained halfway), and when the composition is completed, the shutter is pressed, and the focus is still on the previous focus point.

Focusing refers to adjusting the focus distance when using a camera, the English scientific name is focus, usually digital cameras have a variety of focusing methods, namely autofocus, manual focus and multi-focus methods. Focusing is also called light and focusing. The process of changing the distance between the beams and the position of the distance between the objects through the focusing mechanism of the photographic base leather matching machine, so that the image of the subject is clear.

Summary. Hello dear, you should look at the bright spot in the viewfinder when you focus, if the red bright spot is aimed there, it will focus on the location of that store. The red dot is also called the focus point, and the focus point to the camera in our hand should be 9 or more, and it is generally based on a single point.

Just aim this at the subject when taking a photo. But when taking pictures, you should also pay attention to the autofocus of the focus, otherwise there is only manual focus.

How to adjust the focus of the Nikon D90.

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Hello dear, you should look at the bright spot in the viewfinder when you focus, if the red bright spot is aimed there, it will focus on the location of that store. The red dot is also called the focus point, and the focus point to the camera in our hand should be 9 or more, and it is generally based on a single point. Just aim this at the subject when taking a photo.

But when taking pictures, you should also pay attention to the autofocus of the focus, otherwise there is only manual focus.

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The D90 cannot autofocus, only manual focus, and an autofocus lens can also be attached. If you can't focus after installation, the solution is as follows:

1. You can check the autofocus selection button on the lens to the autofocus position.

2. The focus key is usually marked as A, AF, M A, and the manual focus is marked as MF. Some bodies also have an autofocus selection knob, which is located just near the lens mount.

3. The D90 can autofocus on both the old body-driven AF lens and the new lens motor-driven AF-S lens.

1. Try to use a lens with anti-shake function.

3. In many cases, try to use a smaller aperture.

4. Use manual focus as much as possible.

5. Under appropriate circumstances, the actual distance of the focus on the lens can be displayed.

6. Make reasonable use of zoom lenses.

On the body, when viewed from the front, on the lower right, there is a knob with three positions, which are C, S, M for continuous autofocus, single-shot autofocus and manual focus. In addition: on the lens, there are M and A two gears, M is manual, A is autofocus, and some fully manual ones have no way without this logo.

If the camera mode has been adjusted to auto and the lens supports this function, you can adjust the lens mode to A or S as well.

There is a knob near the lens on the fuselage, see if it is pointing to M, dial it to C or S, there is a switch on the lens, display AF and MF, see if it is on the MF file, adjust to the AF file.

There is an "M-A" knob where the lens is mounted, and if you turn it to A, it will be autofocused.