Manual Control Options
The Optio S55 does not offer manual control of aperture or shutter speed; however, it does include ISO control, manual white balance setting, and an EV compensation function to increase or decrease exposure. Flash modes are also selectable by the user of the S55, and so are manual options for altering image sharpening, saturation, and contrast.
Focus
Auto Focus (6.5)
The Optio S55's autofocus system evaluates five spots in the frame for focus, and selects one to focus on. The standard system is usually the best choice, because it can often account for subjects that aren’t centered in the frame, and other typical photographic situations. The system can be set to “Spot Mode,” which forces the camera to focus on the center of the frame. In either the standard mode or the spot mode, pressing the shutter release halfway will cause the camera to focus. Holding the release down halfway locks the focus until the shutter is pressed all the way, or released.
Manual Focus (2.0)
The Optio S55 offers a digitized manual focus feature projected on the LCD screen. The central part of the frame is enlarged to make focusing easier, but the enlarged portion is not sharp enough to accurately judge focus. It’s not as effective as many other cameras' manual focus features, particularly with just 115,000 pixels of resolution on the oddly kaleidoscopic display.
Metering (7.5)
The Optio S55 contains three selectable metering modes: Multi-segment, Center-weighted, and Spot. These three options are all useful, and they are typical on digital cameras from simple compacts like the S55 to more complicated professional-level DSLRs.
The Optio S55 is set to Multi-segment by default, which is a good thing. In Multi-segment, the camera takes separate light readings of several different sections of the image, and then evaluates them to achieve an even overall exposure. The system should be able to figure out that bright patches in the upper third of the image are sky, for instance, and not be fooled into setting an exposure that makes the sky look perfect, but everything else too dark. In practice, Multi-segment metering consistently produces better results than other metering modes for casual snapshots.
The Center-weighted mode meters the whole frame, but emphasizes the center of the image. The Spot mode meters only a small spot in the center of the frame. Both Center-weighted and Spot are useful when the photographer wants close control of exposure, rather than more generalized snapshot photography.
The Optio S55 metering system performed well, yielding well-exposed images in a variety of situations. The Multi-segment mode handled a bright sky background well, maintaining detail in the foreground subject.
Exposure (7.25)
The mode dial offers eight shooting modes: Auto Select, Program, Pict (which allows the user to choose from several settings appropriate to the subject), Portrait, Night Scene, Landscape, Artistic (which allows black and white and some special effects), and Movie.
The Optio S55 also includes an exposure compensation adjustment for users to manually lighten or darken the picture. Exposure compensation is offered in a +/- 2 EV range, moving in 1/3-stop increments. While the +/- 2 EV range is typical, 1/3-stop adjustments offer a bit more control and precision than the typical 1/2-stop increments on many other similarly priced models.
White Balance (6.0)
The Optio S55 sets its own white balance by default, but also offers four preset settings and a customizable option. The four settings are: Daylight, Shade, Tungsten and Fluorescent. Four settings really is not sufficient; neither “Daylight” nor “Shade” is really quite right for an overcast day, and a single “Fluorescent” setting doesn’t begin to cover the range of ugly, pallor-inducing colors from fluorescent tubes and energy-saving lights. Even tungsten lights range widely. However, the Optio S55 does compensate for the lack of preset options by including a manual setting. This will allow engaged users to attain proper color calibration when desired. The process is pretty straightforward, requiring users to call up the manual setting in the White Balance submenu, and then press the OK button while the camera is focused on something white.
ISO (7.0)
The Optio S55 offers four ISO settings: 50, 100, 200 and 400. The ISO setting will determine how sensitive the imager is to light, and will enable users to adapt to a range of light conditions with some sacrifice of image quality. The 50-400 ISO range is typical of point-and-shoot digital cameras and does not provide much flexibility for shooting indoors with available light. And while this has typically been a common sensitivity range, more and more point-and-shoot cameras intended for casual snapshooters have begun to include 800 and some even 1600 ISO settings. So users of the S55 should prepare to familiarize themselves with the camera's flash settings and capabilities.
Shutter Speed (0.0)
The Optio S55 does not offer manual control of shutter speed, but rather relies on the camera to determine an appropriate setting when balanced with the ISO speed (set by the user) and the aperture (also set by the camera). The S55’s user manual says the shutter speed functions within an automatic range of 4 seconds to “Approx. 1/2000.” I set the ISO to 400 and pointed the camera up into a bright, sunlit sky to check how high the shutter would go. The camera displayed an exposure of 1/1000 of a second at f/4.3. If it could have used a faster shutter speed, it should have – the picture was overexposed.
Aperture (0.0)
The Optio S55 does not offer any direct way of setting the aperture, but the onscreen display shows what setting the exposure system has chosen. At the wide angle end of the zoom range, the aperture ranges from f/2.6 to f/4.8. At the telephoto end, it ranges from f/4.8 to f/7.7.
