By: Erik Vlietinck
Tue, January 29, 2008 - 6:38:00

The Sony Alpha 700 has three different auto focus area options: Spot Focus, Local Focus Area and Wide. The Alpha 700 has 11 focus points to choose from when in Local mode. It also has a F2.8 focus sensor that kicks in when a F2.8 lens (think Zeiss lenses, for example) is mounted --the F2.8 focus sensor is larger than the other focus sensor, and makes for an even sharper focus than is possible with the 11-point sensor.

With its F2.8 sensor, and its 11 focus points the Alpha 700 does better than its competitors and only comes second to the absolute top like the Canon EOS 1D, which has 19 focus points. The question is of course what you should use for best results. As each of these settings has its own benefits, the answer to that question is not straightforward.

Whatever focusing area option you choose, the main subject must located within the boundaries of the area when composing the picture. Or, if you don’t want the subject to appear at the precise location indicated by the focusing area markings, the focus-lock feature should be used.

To lock the auto-focus on a particular subject that you don’t want to see framed in the centre of the snapshot, the Alpha 700 works like most other dSLRs: you press the shutter button halfway down, and re-frame the scene to get what you want. After the focus indicator (the round dot in the viewfinder) signal is given, you press the shutter button the rest of the way down, and the scene is framed the way you want it to.

Now, with the Alpha 700’s Wide focus area setting, you get a rectangular area that is made up of 11 user-selectable (see further) points, and which covers a pretty wide area (about 50%) of the frame. The Alpha 700 will select one of the 11 points to focus on. It will decide which point to use depending on the composition of the scene, its light qualities, depth of field, etc. 

Wide and Spot Focus Mode

Wide is the default setting for the Alpha 700, and while the camera does an excellent job of selecting the right focus point, its two other modes of auto-focussing are better suited for advanced photographers who want to get as much control as possible over what happens in the picture frame. The Wide setting also has its limitations. For example, if you’re going to shoot a low-contrast scene, the camera will find it difficult to “know” what to focus on.

Another problem for Wide auto-focus is when two subjects at different distances overlap each other in the auto-focus area. As the camera can’t possibly know which of the two subjects you want to focus on and the depth-of-field becomes a major decision factor, the camera chokes in this mode.

The second focussing mode, which offers more control to the user, is Spot focus. When the Alpha 700 is in Spot focus mode, you’ll get only the centre of the frame (the small square) in sharp focus. This mode is good for macro photography and for fast moving subjects shot in high-speed mode, because it enables you to exactly get a small portion of the scene in focus, while the rest becomes more blurry --exactly what you need to draw the attention to the focal point that will often be in the centre of the frame with these types of photography. You can also use Spot focus well when shooting portraits. The Spot focus mode does require you to use the focus-lock method when the subject of the photo isn’t exactly in the centre of the photograph.

The third mode is Local mode. Basically, the Alpha 700’s Local mode is the same as Wide mode with the difference being that it is now you --the photographer-- who gets to select the right focus point from the 11 available to focus on. The auto-focus point is selected by first selecting the Local mode and then manipulating the Multi-selector button until the desired focus point lights up in the viewfinder.

The benefits of working yourself with the 11 focus points is that you can hold the camera perfectly still while selecting a point that is out-of-centre, but within the limits of the auto-focus area. This also opens up creative possibilities. For example, suppose you’re shooting a scene in which two subjects are close to each other in the auto-focus area but far apart in terms of depth-of-field. With the Wide setting, the camera may focus on either subject and if you want to make sure it’s focusing on the right one, you may need to reposition the camera so it definitely takes the right subject.

Local Mode For Fast, Spontaneous Shooting

With the Local setting, you don’t have to move the camera and potentially disturb the scene (very important with animal photography, but also with spontaneous portrait photography where the subject may be unaware at the time that you’re shooting him/her).

Local setting is also a good choice when working in circumstances that will fool the Wide setting, such as low light conditions, low-contrast scenes, etc. Local setting may also be faster when you’re used to it, so if you have it “in the fingers”, you will benefit from it when action shooting.

There is of course also the manual focus option, and the Alpha 700 has two different ways to switch between auto-focus and manual focus modes. The first is to switch the rotary switch or button at the front of the camera. You’ll use that rotary switch when you want to switch between auto-focus, continuous auto-focus and manual focus for a longer period of time. 

The button directly next to the Auto-Exposure Lock serves as a quick switch between the more or less permanent setting you prefer and manual mode. You have to hold it down for taking a shot with manual mode (or auto-mode if you’ve set the camera to manual mode before), but if you’re worried about camera movements or awkward handling: it works surprisingly well and doesn’t affect the camera’s stability any bit.