Sunday, October 5, 2008

Focusing Modes-Part 1

A function found in the current range of Alpha DSLRs is the one called Focusing Modes.

There are endless variations to the conditions you can come across when youre taking pictures. Something you need to keep control of is focus. You can be shooting pictures of items for a catalogue, you can be shooting pictures of a sports event, you can be shooting macro shots of a flower, or you can be taking pictures of your pet who stood still for a while but it changed its mind and not its running around, etc. All these examples require a different focusing style, you can either allow the camera to do it or you can do it yourself.

The Sony Alpha DSLRs can handle the different situations you can be shooting at and properly set the focus, but you need to tell the camera which setting to use to achieve the results you want.

This setting is called Focusing Modes.

In the Alpha 200/300/350, if you press the Fn (Function) button, you will be displayed a panel of settings, choose Autofocus mode and you'll see the following:


If you look below the Lens release button, you will see a lever labeled with AF and MF (Manual Focus).

In the Alpha 700/900, you will see a level on the left side of the body, next to the lens mount. It's labeled:

MF(Manual Focus)

Focusing Modes options explained:

AF-S: S for Single Shot. The camera's default setting for focusing. The camera achieves focus once your press HALFWAY the shutter (pressing the shutter all the way down wont achieve focusing). Once the camera has achieved focus, it will lock it and wont focus any more until the next time you half press the shutter. To know the camera has focused, you will hear a signal from the camera and see a green light in the viewfinder.

This mode is useful when you're taking photos of still objects and you don't want the camera to focus anytime but when you tell it to. You can still shoot moving objects with this mode, but you'll need to track the subject and set the focus when you get a chance, because if the subject moves, the focus wont work anymore and youll have to set it again.

AF-A: A for Automatic. This is the setting when you shoot in AUTO. In this mode the camera will decide whether to use AF-S or AF-C mode. How does it work? When you half press the shutter, the camera will determine whether your subject is still or moving, if it's still, the camera will use AF-S and lock the focus; but if your subject is moving, the camera will focus on it AND will continue to track it, keeping it in focus.

This mode is particularly useful for users who dont want to be dealing with the menu or the lever to change the focusing mode setting.

There is one reported downside to this mode, it's rare but it may happen to you.

When using this mode, it may happen that the camera will think that your subject is moving when its not. This will delay a bit the process of taking a picture. If you are shooting a stationary subject and the camera seems to think the subject is moving, use AF-S to solve this.

AF-C: C for Continuous. This mode is used by the camera when you set the Mode dial to Sports (but you can set this yourself as well in other mode). In AF-C, when you half press the shutter and hold it there, the camera continues to focus. This mode is useful when your subject is moving, the camera will keep tracking it and keeping it in focus.

This mode is used by sport photographers, since there is no time to be playing with the focus or else its a missed shot, this mode allows them to track the subject and shoot when they want. You can also use this mode with any moving subject.

Keep in mind that when using AF-C, the camera wont give you an audible signal or a green dot in the viewfinder. Instead it will display a green dot with 2 waves on both sides of it.

Finally, its better if you leave the AF area to Wide. This will allow the camera to decide which of the AF sensors to use while tracking.

In these 3 modes, the camera will automatically focus for you, but under the paramaters you determine (only when you halfpress the shutter, have the camera keep tracking your subject, or allow the camera to decide which of the previous two settings to use).

One thing you need to know is to recognize the focus indicator signals. These will tell you whether the camera has focused or not. This signals appear in the viewfinder.

If you see a:

Green dot lit: Focus is locked and the camera is ready to shoot.

Green dot with waves on its sides lit: Focus is confirmed. The camera will keep tracking your subject. Camera is ready to shoot.

Four waves with no green dot lit: The camera is still focusing and its not ready to shoot. The shutter is locked.

Green dot flashing: The camera can not focus. The shutter is locked.

It's worth noting that there are some situations where the camera will be confused and wont focus. Why this happens?, due to several reasons, such as:

  • A subject low in contrast. If you point the camera to a white wall, a blue sky or a black surface for example, the camera wont be able to focus.
  • Two subjects may be on the same AF are but at different distances. This will confuse the camera because it wont know which subject to focus. You will see the camera focusing one of them, or one and then the other, or none.
  • Repeated patterns. They can confuse the camera because it wont know what or where you want to focus.
  • Subjects that glitter or are too bright. The sun, jewels, car bodies are examples of this. If there is a strong light coming from the subject, the camera's focus will be thrown off.

The good news is that you can get around this problem when it happens.

Next: Part 2-Manual Focus explained and its uses.

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