3.Understanding focus

If the resulting photo is blurred, it is out of focus. This phenomenon is often mistaken for camera shake. It is often the case that if a camera or subject moves during shooting, the resulting image shakes - it is blurred due to camera shake.
It is relatively difficult to distinguish between these two failed photos: one is out of focus and the other shows camera shake. If you carefully observe the image deviation, you could decide that it is a camera shake.

<01>

<02>

<01>This is a photo taken with the camera shaking. If you look closely at the petal, you may find that it deviates in a diagonal direction.
<02>This is an out-of-focus photo. I used the manual focusing mode to take this photo so that it was out of focus.
In the automatic focusing mode, this kind of photo cannot be taken.

If the camera shakes, the whole image deviates, while if the subject moves, only the subject that has moved shows drift.

The reason why an out-of-focus photo makes you nervous is that you want to see the subject more precisely. In extreme instances, if you are not interested in the subject or the resulting image, focusing doesn't matter.
Accordingly, it is essential to focus on the subject you want to shoot or emphasize. The subject varies depending on the photographer's intentions, so the automatic mode of a camera does not always result in the desired photo. This is a starting point from which you learn and master how to focus on a subject.

<03>

<04>

<03>The sunflower is in focus. You can see the details of it.

<04>The background is in focus. Since you want to look at the sunflower normally, this photo bothers you, doesn't it?

Do you know the term "Depth of Field?" It refers to the range of distance within which a subject can be in focus, and can be changed by the lens aperture. This means you can change the extent to which the background is blurred while the subject is in focus. This function is special to SLR cameras. Digital compact cameras can also blur the background but not as much. I will describe the depth of field in detail in the sixth issue. Don't miss it.

<05>

<06>

<05>The sunflower is in focus and the background is relatively sharp because the depth of field is "deep."

<06>The sunflower is in focus but the background is blurred significantly because the depth of field is "shallow."

When focusing on a desired subject, you tend to think that only the subject is in focus, but actually, your camera focuses on the flat surface.
This fact may be difficult to understand, so look at the following photos to imagine what happens with them. They show that all the subjects standing side by side are in focus, but the longer the longitudinal distance from the focal plane, the more the subject is blurred.

<07>

<08>

<07>The focus is on a flat surface.
<08>All the subjects standing side by side are in focus.

Nikon D-series cameras have several focus areas (focus frames) in their finder.^* The focus area aims to focus on a subject.
Namely, the camera allows you to select which subject on the screen should be in focus, as you wish.
You can easily focus on a subject you want to shoot or emphasize by putting it in a specified focus area.
This function is essential for focusing on a subject with a digital SLR camera, so be sure to master it.

* Nikon D50, D70, and D100 have five focus areas on the screen, while Nikon D200 and D2-series have eleven focus areas. Here, only three areas appear in green to make the operation of this function more understandable.
* If "Nearest dynamic AF mode" (to be described later in this issue) is specified, you can select no focus areas.

<11>
Multi-selector. Moving this button from side to side and up and down allows you to select an arbitrary focus area.

<12>
Selecting the left area focuses on sunflowers standing at the rear.

<13>
Selecting the center focuses on the one in the center.

<14>
Selecting the right focuses on the one at the front.

If you could select any focus area quickly, the degree of photographic freedom would increase greatly. However, when you want to give priority to composition, the subject you want to shoot is not always in the desired focus area.
In this case, use the focus lock function. To do this, press and hold down the shutter release halfway.^* This is an often used operation, so master it by practice.

* If "C" (Continuous) is set for the AF mode, press the AF lock button instead of the shutter release.

<15>
Align a focus area with the subject you want to shoot.

<16>
Press the shutter release halfway or push the AF lock button to lock the focal point of the lens.

<17>
Move your camera to get the desired composition, and then press the shutter release. The sunflower is not blurred because the focal plane does not change even if you change the orientation of your camera.

(The focus lock function is enabled in any focus area. The center area is used for this explanation.)

The automatic focusing function has two options: "AF mode" and "AF area mode."
The AF mode has three options for automatic focusing: "AF-S" (Single), "AF-C" (Continuous), and "AF-A" (Automatic). I recommend the last one for general photography because it selects AF-S or AF-C automatically.
The AF area mode allows you to specify how to use information in several focus areas and presents three options: "Single area AF mode," "Dynamic AF mode," and "Nearest Dynamic AF mode." The best one of these options is automatically set depending on the settings for the exposure mode. In the fully automatic mode or many image program modes, the nearest dynamic AF mode is chosen to focus on the nearest subject in all the focus areas.

<18>
The AF mode is chosen. The AF-A mode selects AF-S or AF-C automatically.

<19>
The AF area mode is chosen. If you leave the photo settings to your camera, I recommend the nearest dynamic AF mode.

When you take a photo of a landscape or flowers, or a portrait, the AF-S and single area AF modes are the best combinations.
The former mode allows you to press the shutter release halfway to lock a focal plane. It also prevents the resulting photo from being blurred because the shutter is disabled when the subject is not certainly in focus.
The latter mode allows you to select only one focus area in which there is a subject you want to shoot.

<20>
The AF-S (Single AF Servo) mode is chosen. This mode is used when priority is given to focusing.

<21>
The single area AF mode is chosen. You can select an arbitrary one from the several focus areas. This mode is used when priority is given to composition.

If the subject is someone engaged in a sport, or a child or pet moving freely, it is difficult to select a focus area. Of course, it is almost impossible to manually focus on such a subject.
In this case, the AF-C mode enables the automatic focusing mode continuously, and the dynamic AF mode effectively uses information resulting from multiple focus areas to focus on a subject. Both modes are suitable.

<22>
The AF-C (Continuous AF Servo) is chosen. It is best suited for a moving subject because the automatic focusing mode always works. The shutter is enabled though no subject is in focus, which means that priority is given to the shutter at the right moment.

<23>
The dynamic AF mode is chosen. It allows you to select a focus area and uses information resulting from not only the chosen area but its surroundings to bring your camera into focus. Therefore, you can take a picture of a moving subject while chasing it.