Manual Control Options
Characteristic of the A-series, the Canon PowerShot A650 IS offers a blend of automatic and manual options. There are a full range of manual exposure modes and complete control of shooting parameters, including white balance, shutter speed, and aperture. This gives users the option to simply point-and-shoot or get more creative.
Focus
Autofocus (7.75)
The A650 IS has a nine-point through the lens autofocus system. The focus points are arranged in a 3 x 3 grid over the image. Users can choose one of four basic AF Frame selection modes:
• Face Detection: selects frames nearest the detection of up to three faces (must be frontal, not at an angle or profile) - reverts to AiAF if no faces detected;
• AiAF: selects frames based on a statistical analysis of the scene properties;
• Center: always uses the center frame (useful for “focus and shift” technique);
• FlexiFrame: allows selection of any one of the nine frames.
Pressing the bottom of the navigation ring, in Recording mode, pops up an onscreen menu that selects the focus mode. Three choices are presented, as icons and text: macro (or close-up), manual focus, and normal (auto) focus.
One moves between these focus modes by pressing the top or bottom of the navigation ring while the focus mode control is onscreen. One has to do this fairly soon after the control pops up, or it will go away and you will have to start over.
In normal autofocus mode, the focus range is from 1.6 feet to infinity. In macro or close-up autofocus range is from about 0.4 inches to 1.6 feet. When zooming, a bar graph pops up onscreen that shows the current zoom level. The zoom range not possible in macro mode will be marked on this bar graph in yellow. Best results are obtained in Macro mode at the wide end of the zooming; close-ups are not possible at the telephoto end.
The Canon A650 IS focuses quickly in bright light. In low light the camera emits an orange autofocus assists beam to aid in focusing.
Manual Focus (3.0)
While primarily an autofocus camera, it has a somewhat coarse manual focus mode. It also offers a mode in which autofocus “fine-tunes” a first approximation made by manual focus.
In manual focus mode, a bar graph pops up onscreen that shows the current focus distance. One judges focus quality from the live preview. To assist this, the image area around the current focus point appears magnified.
Exposure (7.5)
In Record mode, the exposure button brings up an onscreen control that allows the exposure compensation to be set. The image will then be recorded as darker or lighter than normal.
This is useful in tricky lighting situations, where the camera might ordinarily be fooled into making an incorrect exposure. The camera normally assumes that a scene averages out to medium brightness overall (that is, dark areas are equally balanced by light areas). Suppose as an example that we are photographing a backlit subject. The large bright background behind the smaller, darker subject might normally fool the camera into underexposing the picture. By setting a positive amount of exposure compensation, we counteract the underexposure with an equal amount of overexposure. The result is a correctly exposed subject (even though, less importantly, the background may be a little overexposed).
When the exposure button is pressed, a small scale pops up on the screen, overlaying the bottom right portion of the preview image. This scale ranges from –2 to +2, in EV units; 0 is normal, - is darker and + is lighter. A small green arrow shows the current value. Pressing the left arrow on the navigation ring will darken the image; the right arrow will lighten it. The effect of the change shows up immediately in the live preview (it darkens or lightens). The setting will be remembered until the next time it is changed, even if power is shut off. Pressing the menu button removes the control from the display.
Exposure compensation is not available when the mode dial on top of the camera is set to Movie mode, or to auto or manual exposure.
The full range of PASM modes are available, along with a dozen presets, giving the user a lot of control over exposure.
Metering (8.0)
The camera offers four light metering patterns:
• Evaluative: computes exposure from a statistical analysis of image properties;
• Center-Weighted Average: averages entire image with extra weight given to center;
• Center Spot: meters a small spot, fixed to the center frame;
• Frame Spot: meters a small spot, linked to the focus frame.
White Balance (7.5)
The camera provides the follow white balance settings: Automatic, Daylight, Cloudy, Tungsten, Fluorescent, Fluorescent H, Underwater, and Custom. White Balance is set, in Recording mode, by pressing the “FUNC SET” button twice, to bring up the menu of shooting parameters. Scroll vertically to the “AWB” (white balance) icon on the left using the navigation ring, then scroll horizontally using the ring to select the desired value from the icons arrayed along the bottom. Press the “FUNC SET” button again to select the new value. The new setting will be remembered until it’s changed again.
ISO (8.0)
The camera offers a range of fixed ISO sensitivity in many Record modes. ISO values of 80, 100, 200, 400, 800 and 1600 are available at full resolution. ISO 3200 is available at severely reduced resolution.
In Auto ISO mode, the ISO sensitivity is adjusted to yield the best image quality for the available light. In practice, this means the lowest ISO sensitivity is consistent with the selected aperture and shutter speed settings. This ISO mode is available only in the Program, Av, Tv and Manual exposure modes.
High ISO Auto mode is restricted to the Program and Auto exposure modes. In this mode, a higher ISO level is automatically selected, to force faster shutter speeds in low-light situations. A higher tolerance for image noise is required as a tradeoff.
When the ISO button is pressed in Recording mode, a small scale with possible ISO values (AUTO, HI, 80, 100, 200, 400, 800, 1600, 3200) is overlaid on the image. The currently selected value is highlighted, and also displayed below the scale. Pressing the left or right arrows on the navigation ring allows the selection to be changed. The control is automatically removed from the screen after a couple of seconds of inactivity, and the current value is remembered even if power is shut off.
One has to be fairly quick to hit the navigation ring after bringing this control up, or it will go away and you’ll have to start over.
The ISO 80, 100, 200, 400, 800 and 1600 choices are available only in the Program (P), Aperture Priority (Av), Shutter Priority (Tv) and Manual (M) exposure modes. In Auto and Program modes, the user can choose either Auto or HI ISO. The ISO 3200 choice is available only in the Scene mode.
Shutter Speed (6.5)
The camera has an electronic shutter with shutter speeds from 15 to 1/2000 seconds. These speeds are user-settable in Aperture Priority and Manual Record modes; in all other modes they are selected automatically by the metering system.
Since electronic shutters are noiseless, the camera emits a synthetic “shutter noise” through the built-in speaker, to provide audible feedback to the user.
Aperture (6.75)
The camera has a maximum aperture of f/2.8 at the wide angle end of the zoom, and a maximum aperture of f/4.8 at the telephoto end. The aperture can be stopped down as far as f/8.0, in 1/3 EV steps. The aperture can be set manually in the Av (Aperture priority) and M (Manual) Shooting modes. In all other modes it is set automatically.
