Manual Control Options
Like many of its A-series siblings, the Canon PowerShot A640 offers a nice range of automatic to manual control. Users can graduate from the scene modes to the program and priority modes, to the fully manual mode. The shutter speed and aperture are changed using the multi-selector and the exposure compensation button. This isn’t the fastest or easiest way of doing things, but there just isn’t room for jog dials galore on the A640’s body. Still, the amount of manual control offered is great for the price of this digital camera.
Focus
Auto Focus (7.75)
The Canon PowerShot A640 has a 9-point through-the-lens auto focus system that has three modes: AiAF (default), FlexiZone, and Center. The AiAF system lights up green boxes around various areas of the frame to show where the camera is focused. The Center option is fixed to the middle, of course. The FlexiZone AF mode is very interesting. It allows users to manually move the focus point all around the frame with the multi-selector. The auto focus system works quickly and effectively, something that can’t be said of all compact digital cameras. It does focus much better and faster at the widest focal length over the telephoto end. The A640 normally focuses from 1.5 ft to infinity, but it has a macro mode that shortens that range. The macro mode is accessible from the bottom of the multi-selector and can focus as close as 0.39 inches in wide and 9.8 inches in telephoto. The A640’d auto focus system performed decently in low light, although it did take more time. The camera is equipped with a small, orange auto focus assist lamp to illuminate subjects that are dimly lit.
Manual Focus (2.5)
The bottom of the multi-selector accesses the manual focus mode in addition to the macro mode. Users can scroll right and left with the multi-selector to change the focus; as they do so, a scale shows up with distances on it. In the recording menu, users can choose whether to activate a zooming function in the manual focus mode. It enlarges the center of the image so it’s easier to see. This function isn’t complimented by the LCD screen’s resolution though. With only 115,000 pixels on the 2.5-inch screen, it is hard to focus on detailed subjects.
ISO (7.0)
Newer PowerShots are equipped with a Digic III processor that allows for even greater sensitivity, but the A640 still has a decent range from 80-800. This model also has automatic and High ISO Auto settings; the latter is for low light photography. All of the options are located in the Func./Set menu with a live view when scrolled through. This is a nice setup, and it helps users choose the best setting for the exposure.
While the available options were sufficient, the A640's noise levels were unacceptably high. To view a more elaborate report on the A640's noise levels and image quality, refer to the testing/performance section of the review.
White Balance (7.5)
Also located in the convenience Func./Set menu are the Auto, Daylight, Cloudy, Tungsten, Fluorescent, Fluorescent H, Underwater, and Custom white balance settings, also with a live view. These proved to be fairly accurate, with the Custom option trumping them all as usual. It is simple to set, and that is imperative for the target audience of this camera. There is a small bracket in the center of the frame where the white balance is measured, so rather than filling a room with white, users need only to frame something white in the tiny bracket. An on-screen prompt alerts users to push the Menu button when the white subject is framed.
Exposure (7.5)
There are 21 exposure modes on the Canon A640 ranging from automatic to manual. Many of the scene modes allow users to adjust the exposure compensation though. +/- 2 EV is available in steps of 1/3 via the designated exposure compensation button. There is a live view along with the exposure compensation scale that is shown at the bottom right corner of the screen.
Metering (8.0)
There are live views of the three metering modes in the Func./Set menu: Evaluative, Center-weighted Average, and Spot. The first is the camera’s default, and works well in average lighting but is fooled by backlit subjects. For those situations, the other two modes work well. For pictures when the subject is off-center and the lighting a bit strange, the Spot mode works well. Its tiny metering point can be manually moved along with the FlexiZone AF point. This grants more flexibility to users of the Canon A640.
Shutter Speed (7.0)
The A640 offers a wide shutter speed range for a compact digital camera: 15-1/2500th of a second. The camera automatically chooses the shutter speed unless in the Manual or Shutter Speed Priority (Tv on the dial) modes. There is no live view when changing shutter speeds in the priority mode, but there is one in the manual mode – which is helpful. When the aperture is open to its brightest f/2.8 in the manual mode, the shutter speed is limited to 1/1250th of a second. This shouldn’t hinder any photographic opportunities.
Aperture (7.0)
The A640 has a 4x optical zoom lens with maximum apertures of f/2.8 at wide and f/4.1 at telephoto. The f/2.8 aperture is standard now on lenses, but the f/4.1 is at least a full stop brighter than what competing cameras offer. Throughout the lens range, f/8 is as small as the aperture goes; this is also common on compact digital cameras. Once again, there is a live view when switching apertures in the manual mode but not in the priority mode. Here are the choices at the widest focal length: f/2.8, f/3.2, f/3.5, f/4.0, f/4.5, f/5.0, f/5.6, f/6.3, f/7.1, and f/8.0. At telephoto, the only addition is the maximum f/4.1 setting with those above it still available.
|
