Testing / Performance
*To evaluate the color performance of EX-Z57, we captured a sequence of images of an industry standard GretagMacbeth color chart, illuminated by Lowell softbox lamps. The results were uploaded into Imatest Imaging Software to analyze the color information and determine the accuracy of each rendered tone. Images recorded with the EX-Z57 were shot on a tripod, using the camera’s lowest ISO setting (50) and custom white balance. These tests are designed to indicate the camera’s ability to render accurate tones, as they originally appeared in the scene; the score is not a measure of tonal brilliance or vibrancy.
Below is a copy of the color chart modified by Imatest; the outer square contains colors produced by the Casio Exilim EX-Z57, while the vertical rectangle is the ideal. The inner square is camera’s reproduced tone, corrected for luminance.
Below is a more quantitative graph depicting the EX-Z57’s color performance. The squares represent the tonal ideal, while the corresponding circles display the camera’s rendering of that particular color. The greater the distance between the two shapes, the less accurate the camera’s reproduction of that tone.
The Casio Exilim EX-Z57 scored low on our color tests, earning just a 5.83 overall color score. Analyzed images were 7.5% over-saturated, which is minimal, but nearly all of the individual hues strayed to some extent from the ideal. This is particularly noticeable in the under-saturated blue and green channels. Many of the cooler tones lacked vibrancy, while orange and yellows hues were shifted, resulting in the camera’s 5.83 overall accuracy score.
While the EX-Z57’s color performance was certainly substandard, the lack of tonal accuracy will not be detrimental to all users. Those looking to attain a "realistic" reproduction of the scene, the way it appears to the human eye, will be greatly disappointed; however, snapshooters interested in the EX-Z57 as an instrument to merely capture moments in time should not be overly disturbed. Having said that, there are many similarly priced models made by Kodak, Canon, and Fuji that produce far more accurate tones with increased vibrancy and aesthetic appeal.
**Still Life Scene
**Below is a shot of our Joseph Cornell-inspired still life scene photographed with the EX-Z57.
Resolution / Sharpness*(2.73)
*To test the resolution of the EX-Z57, we shot a number of images of an ISO resolution chart and imported the results into Imatest Imaging Software. The software reads the imported file and determines the actual number of pixel used to form the image. The images were recorded in a controlled studio setup using Lowell softbox lamps. The images were captured using the camera’s various available settings and modes, to get a proper feel for the camera’s capabilities. We report the best results we were able to attain. The results are given as the actual number of detected pixels and as a percentage of the advertised resolution. When this is done, cameras that score over 70% of their advertised pixel count are viewed as "good," while scores exceeding 80% are "very good." Anything beyond 90% of the marketed resolution is "excellent" and quite rare.
The Casio EX-Z57 was sharpest around 40-45mm (equivalent focal length), at f/4.5. The camera achieved a real resolution score of 2.73 megapixels, with 24.9% oversharpening. This is roughly 56% of its advertised resolution and a very low score. While the EX-Z57 is designed for both portability and sharing images on its large screen, many competing cameras offer a similar styling with resolution scores beyond 70% of their marketed capabilities. For users of the EX-Z57, the lack of resolution will not be noticeable in small 4 x 6 prints or images displayed on the camera’s large LCD; however, when users attempt to make larger prints or view full resolution images on their television sets, the image quality will be far below expectations.
Noise – Auto ISO*(2.79)*
Almost exclusively designed for snapshooters, users of the slim and stylish Casio EX-Z57 are likely to set the camera to automatic and point and shoot. In this situation, many users might be surprised to see the granulated look of the EX-Z57’s produced images. With Casio attempting to market the camera’s 1/2.5-inch CCD, users might feel a bit misled. We tested for sharpness (above) and found that the camera fell short of its marketing claim; however, the biggest surprise was the amount of perceivable noise present in images produced by the EX-Z57 in auto mode. The camera earned just a 2.79 noise score when set to Auto ISO, one of the lowest scores of any camera we have tested.
The tests were conducted under profuse lighting, illuminated by three Lowell softbox lamps, with over 300 lux of illumination on the scene. Given the situation, we found it surprising that the camera elected to set the ISO at 200. The ISO 50 or 100 setting should have been sufficient and would have cut down on the amount of noise in the image tremendously. Fortunately, the EX-Z57 does enable users to set the ISO speed manually; an option even the most hands-off users should take advantage of when shooting with the EX-Z57.
Noise – Manual ISO*(5.13)
*For cameras that provide manually alterable ISO settings, we test the amount of noise produced at each available rating. The results are put into a regression analysis to determine an overall manual ISO score. The incremental results are displayed in the graph below, with the EX-Z57’s sensitivity ratings placed along the horizontal axis and the resultant noise plotted on the vertical axis.
The EX-Z57 produced images of far greater quality when the ISO settings were manually set by the user. The camera’s 50 and 100 ISO settings were similar, with a moderate increase in noise at the 200 setting. It is not until the camera is pushed to its ISO 400 setting that images truly become fraught with noise. The lack of a clean looking ISO 400 setting might be a problem when paired with the camera’s weak flash unit, but for those snapshooters photographing outdoors or under substantial indoor illumination, the resulting images should be of acceptable clarity.
Low Light Performance*(3.0)
*Our low light evaluations are designed to show the camera’s ability to record at night or in minimal illumination without the use of the flash. We do this by recording a sequence of four images at decreasing light levels. The cameras are tested at 60, 30, 15, and 5 lux to approximate performance in typical low light conditions; 60 lux is comparable to a moderately lit bedroom after dusk, while 30 lux is roughly parallel to a single 40 watt lightbulb. Tests shot at 15 and 5 lux display the camera’s recording capabilities in near darkness. All shots were recorded on a tripod, using the camera’s 10 second self-timer.
Click on any of the above charts for additional image analysis
The Exilim EX-Z57 is designed with an abundance of presets, some of which are oriented for low light situations, providing the user with an extended shutter speed range. With just a 400 maximum ISO setting, we expected the camera to have some difficulty in the compromised lighting setup. As predicted, the Casio EX-Z57 was not qualified for low light usage without the assistance of the flash. As you can see in the chart above, images captured at 60 lux lacked color vibrancy and contained a lot of noise. In the Night Scene preset, which enables exposures of up to 4 seconds, the camera was able to maintain a decent degree of visibility, but could not attain focus. The focusing difficulty appeared to be unavoidable and indicates that flash assistance will be a necessity when shooting in low light. While the incessant use of a flash will not deter some potential consumers, others may view the inability to record in natural light and capture the ambiance of a night scene to be unacceptable.
**Speed / Timing
***Start-up to First Shot (6.34) *
The Casio EX-Z57 takes its time to get going, requiring 3.66 seconds to record its first shot. This is extremely slow compared to other competing cameras and will test the limitations of its long enduring battery – if it's not left on, photos will be missed.
*Shot to Shot Time (7.86) *
Taking over 2 full seconds between images, the EX-Z57 is one of the slowest cameras in its styling to record subsequent frames. Speed is generally a strong marketing slant for this type of camera and many similar models shoot in 1/2 – 1/4 of the time the Z57 takes.
*Shutter to Shot Time (8.98) *
Shutter lag is perhaps the most import speed requirement for many consumers and fortunately, it is the only instance in which the EX-Z57 performs quickly. With just a 0.01 second shutter lag, once powered on, the user should not be concerned with the Z57's speed, unless multiple frames are needed.