Canon PowerShot Pro1New level of sophistication takes over the top spot in the PowerShot line.<<Viewfinder :(Previous) | (Next): Exposure & Flash>> Page 5:OpticsReview First Posted: 05/14/2004 |
Optics
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The
Pro1 features a built-in, 7x, 7.2-50.8mm zoom lens, equivalent to a 28-200mm lens
on a 35mm camera. This amounts to a range from good wide-angle to very good telephoto
coverage. This is no ordinary PowerShot lens, however, as the surrounding red
ring attests. This ring is seen only on Canon's L-series professional lenses,
most of which include a low-chromatic aberration Fluorite element. This lens also
includes a UD (Ultra-low Dispersion) element and an Aspherical lens, all of which
work to reduce chromatic aberration, spherical aberration, and produce sharper
images while keeping the lens compact.
When the camera is powered on, the lens telescopes out from the camera body into its operating position (extending just under an inch from its stowed position), then retracts again when the camera is shut off. Measuring from the body, it comes out about 2 1/4 inches. Zoomed out fully, it moves out about 2 1/4 inches from its stowed position, or 3 5/8 inches from the body. The motor is relatively quiet, and the action is smooth. A plastic lens cap protects the lens when not in use. No tether is included, nor is there a lashing point on the lens cap, something that I personally sorely miss. (I'm notorious for losing lens caps.) Focus can be automatically or manually controlled, with a range of 1.6 feet (50 centimeters) to infinity in Normal Focus mode. Macro mode features a focus range of 3.9 inches to 1.6 feet (10 to 50 centimeters). A new Super Macro mode, entered via a menu setting, enables closer focusing, ranging from 1.2 inches to 1.0 foot (3 to 30 centimeters). The aperture adjusts automatically or manually, with an f/2.4-3.5 to f/8 range, depending on the zoom setting. An internal neutral density filter can be deployed via a menu option to cut the light transmission by a factor of 8 (3 f-stops), permitting the use of wider apertures or slower shutter speeds in bright conditions. (A very handy feature, should you ever be in a position to need it.)
Manual focus is activated by depressing the Manual Focus (MF) button on the back of the camera. Once pressed, a distance indicator appears on the LCD monitor, providing a reference scale for focusing. Turning the zoom control on the lens controls the focusing distance, which is displayed via a vertical bar graph on the LCD monitor. The distance marks on the focusing scale are shown in metric or English units, as selected in the Setup menu. The readout shows meters or feet, centimeters or inches, depending on the range. I found the roughly 2x viewfinder enlargement that accompanies Manual Focus mode very helpful in setting focus, although even more magnification would be welcome. As soon as you turn the zoom ring to adjust focus (while in MF mode), an enlarged portion of the subject appears in the center of the LCD display, making it easier to determine exact focus. While the manual focus system works quite well, I'd really like to see more numeric distance markings on the scale: In low light conditions, I've often found it necessary to set focus by estimating the distance, but the very limited number of specific distance markings on the Pro1's manual focusing scale make it difficult to do this.
The Pro1 also features a Hybrid AF system, which is designed to offer quicker autofocus by employing two methods. Two passive sensors on the front are Canon's Phase Detection Autofocus, seen on earlier 35mm point-and-shoot cameras. This mechanism helps the iSAPS system determine where to put the lens for quicker contrast-detection autofocus. With such a long lens, some systems we've seen will seek across the entire focus range before deciding on the right focus area; using both passive and contrast detection methods, Canon has largely eliminated this problem, but the hybrid AF system didn't result in full-autofocus shutter lag numbers as low as I've seen with other top 8-megapixel models.
Although I didn't see shutter lag times as fast as I'd expected from the Pro1's hybrid AF system, I was very pleasantly surprised by its performance under low light conditions. While the autofocus time could stretch rather long as the light got dimmer, the camera was able to focus under incredibly dim conditions, actually below the 1/16 foot-candle lower limit of my standard low-light test. This is a good thing though, because the Pro1's autofocus-assist illuminator (a bright white LED hidden beneath its flash head) is only available when its flash is enabled. This is the same behavior as found on the Digital Rebel SLR, which I also objected to there. Fortunately, in the case of the Pro1, the camera can focus surprisingly well under dark conditions with no help from the AF assist light.
When shooting in Autofocus mode, the Pro1 offers both Continuous and Single Autofocus functions. In Continuous mode, the camera is constantly adjusting focus, even when the Shutter button is not depressed. In Single mode, the camera focuses only when the Shutter button is depressed halfway, which helps to conserve battery power. Given that the camera is continuously adjusting the focus in Continuous AF mode, you'd expect the shutter delay to be less. (Since the lens ought to be close to optimum focus most of the time.) Like most cameras with continuous autofocus modes though, the Pro1's shutter lag was actually slightly longer in Continuous AF mode in my tests. It might thus be useful for tracking moving subjects (which I have no quantitative way of testing), but don't look to it as a means to improve shutter response. Another issue with the Pro1 is that the screen freezes while the camera is focusing, an effect that also gets longer when in continuous mode. While the display is frozen, it's easy to lose track of your subject, an unfortunate aspect of this otherwise impressive camera. (This viewfinder freeze was quite annoying in my shooting with the camera, to my mind the single biggest drawback of the Pro1.)
Like the G3 and G5 before it, the Pro1 features Canon's "FlexiZone Autofocus" system, which lets you change the focus area by scrolling the focus-area box smoothly up or down, right or left on the LCD or EVF. The AF area can be positioned anywhere within a central area covering roughly 60 percent of the frame. To move the AF area, press the SET button while in Record mode. The central box that marks the AF area will turn green, indicating that it is selected. Using the up/down, left/right arrows on the Four-Way Arrow pad, you can then move the AF box smoothly around the frame. When you have it positioned where you want, press the SET button again to deselect it. Once the focus point is set and the picture is framed, pressing the Shutter button halfway will turn the box green if the selected area is in focus or yellow if it's not. Through the Record menu, you can choose to have the Spot Metering function use this same area for its exposure determination, using the Spot AE Point submenu. As you zoom in toward telephoto, the AF point increases in size. This is in response to the change in the relative size of the area covered by the Hybrid AF's Phase detection sensors, whose detection area increases in size as you zoom in just like everything else in the frame.
Canon's G3 model was the first camera I had seen with an Auto Focus Bracketing feature on it, and I'm pleased to see it continued on the Pro1. Auto Focus Bracketing (AFB) snaps three exposures in rapid succession, shifting the focus slightly after each. This function is accessed through the FUNC button's sub-menus, and must be done in the Manual Focus (MF) mode. You can set the focus step size from one to three in arbitrary units, by depressing the FUNC button, scrolling to the AFB option with the Omni Controller, and then using the Omni Controller again to choose the amount of variation between shots. Depress the Set button, then fully depress the Shutter button to start the series. The camera makes all three exposures with just one press of the Shutter button.
Digital Zoom is activated through the camera's Record menu and is operated with zoom ring. The amount of total zoom (optical plus digital) is reported in the top right corner of the LCD monitor whenever digital zoom is engaged, and can go as high as 22x. (The 22x total zoom corresponds to 7x optical plus 3.2x digital.) Digital Zoom is not available when shooting with the Pro1's Movie mode, Super Macro mode, or when using the RAW file format. (It's important to note that digital zoom simply enlarges the center of the CCD image, resulting in some loss of image quality in the form of reduced image sharpness that's directly proportional to the amount of digital zoom used.)
Like the G-series, the Pro1 accommodates several optional conversion lenses via a lens adapter kit, so you can extend your camera's wide angle or telephoto capabilities with high-quality optics. The adapters attach via a bayonet mount on the lens barrel, and a small button below the lens on the front of the camera releases a catch, letting you remove the cosmetic collar surrounding the lens barrel and reveal the flanges of the bayonet mount.
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