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Casio EXILIM EX-F1 Digital Camera Review

by Steve Morgenstern
Published on July 23, 2008

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It may look like an SLR, but at heart the EX-F1 is a rocket-powered point-and-shoot. The 1/1.8-inch CMOS image sensor, while tweaked for speedy performance, is much smaller than the sensor in an SLR, which led us to expect lower performance in lab testing. And while we did find color accuracy was sub-par even when compared to other point-and-shoots, we were pleased to find scores for resolution, noise and dynamic range that surpassed typical performance for other ultra-zoom cameras we've tested.


Color (5.71)
When you look at a photo and it just doesn't seem to capture the moment you remember, very often it's the color accuracy (or lack of it) that's putting you off. You were inspired by a particular blue sky, or green fields, or glowing cheeks, but when you look at the photo after the fact, the emotional impact suffers because the hues are off. Accurately assessing how color reproduction varies from camera to camera requires more than a good set of eyes – it takes a trip to the lab, with a consistent testing regimen. We photograph an industry-standard Gregtag Macbeth color chart at a wide range of exposure settings under studio lighting. The resulting images are tested using the sophisticated Imatest image analysis software to determine the difference between the known color values from the chart and the colors the camera recorded. The image shown below was produced by Imatest during testing of the EX-F1. It shows the original chart color (the small rectangle on the right in each box), the color captured by the camera (the outer rectangle) and the captured color corrected for luminance (the inner square).


Accurate color reproduction isn't the strong suit of the EX-F1. While not terrible, the problem remains consistent throughout the range of ISO settings. We also found the images were significantly undersaturated, which gives colors a dull appearance.

The following chart shows how a range of colors vary between ideal values (represented by the squares) and the colors found in photos taken with the EX-F1 (shown in the circles). The shorter the line, the more accurate the color.


Shorter lines in this Imatest chart
indicate more accurate color reproduction.

 
There's a clear pattern here. Purples and reds are reproduced with very good accuracy, while blues, greens and yellows are pretty far off the mark. The good news here: flesh tones are likely to look about right, and that is an area where viewers are especially sensitive.


Casio EX-F1 Color Scores


The color performance score for the EX-F1 is compared here with the results for a similarly priced SLR, the Canon EOS Rebel XSi, and three long-lens point-and-shoots we've put through our lab testing. It's interesting that in this test, the point-and-shoots aren't necessarily at a disadvantage when compared to a pricier SLR. Still, the Casio is unimpressive, though on a par with the compact Olympus SP-560 UZ.

Resolution (8.04)
Image resolution and megapixel count don't necessarily go hand in glove. A camera boasting lots of megapixels on its sensor may still disappoint when it comes to the actual sharpness of the images it captures due to differences in optical performance, signal processing and other variables. That's why we shoot literally hundreds of photos of an industry-standard test chart (shown below) at several focal lengths, analyze them using Imatest and review the results in detail.

This resolution testing produces results measured in line widths per picture height (lw/ph), indicating how many progressively thinner, alternating horizontal and vertical lines on the chart the camera can reproduce before it all starts looking like a grey blob. The higher the number, the sharper the image.


The industry-standard resolution chart we use for testing

The best-case result for the EX-F1 was 1857 horizontal and 1734 vertical, shot near the wide end of the zoom lens range. Imatest indicated that rather than artificially boosting the perceived resolution through digital sharpening algorithms, the camera took a conservative approach, slightly undersharpening the image. The figures for the middle of the camera's extensive zoom range indicate continued strong lw/ph figures, though cranking the lens to its full telephoto setting did seriously impact results. Still, looking at enlarged photos taken even at maximum range, handheld in bright sunlight, the images deliver perfectly acceptable sharpness.

As seen in this comparison chart, the EX-F1 surpasses the long-zoom competition handily in most cases, though as expected it falls short when compared to the Canon XSi SLR, with its larger image sensor.

 

Casio EX-F1 Resolution Scores

Noise – Manual ISO (8.93)
Take a photo without flash in low light and look closely at the results. See the clumps and imperfections in solid-color areas? That's noise, an inevitable imperfection caused by the mass of circuitry required to take the light streaming through a lens and turn it into digital ones and zeros. While it's most noticeable in low-light photography and when making extreme enlargements, noise is a factor in every digital photo you take, to a greater or lesser extent. Manufacturers try to tame the beast by minimizing noise production on the front end, and digitally processing the sensor's initial signal to identify and remove noise before saving the file on the back end. Many cameras give you the option of turning that back-end noise reduction processing on or off. For the EX-F1 Casio decided to automatically use noise reduction for any shot taken at an exposure setting of 1 second or longer (time is one factor in increased noise production), and not to filter for noise at high ISO settings, which is another frequently employed technique. This automatically triggered noise reduction for long exposures can't be turned off by the user.

Our noise testing procedure calls for shooting color images at a range of ISO settings and having Imatest examine the results to determine how much noise each setting produces. These results are then graphed to reveal both the noise level and the rate of increase as light sensitivity ramps up. In the chart below, the percentage of noise in the captured images is shown on the left axis, the increasing ISO at the bottom.

Casio EX-F1 Manual Noise

 

Despite its small sensor size, the EX-F1 produced exceptionally low-noise images at low ISO settings, though the graph does rise steeply as ISO increases. Overall we're impressed with this level of performance, particularly when compared to other cameras we reviewed. As seen in the chart below, the Casio surpassed the other ultra-zoom models in this benchmark test.

Casio EX-F1 Manual Noise Scores

Auto Noise (6.24)
In addition to testing by manually setting the ISO, we shoot using the Auto ISO setting, letting the camera pick its own level and scoring the result. In this case the EX-F1 shot at a reasonable ISO 200 and produced a good, if not outstanding, result. As seen below, the EX-F1 bested the point-and-shoot competition here and fell only slightly short of the Canon SLR. In practical terms, this test is less important than our manual noise testing, since it's a simple matter to set an appropriate ISO level while shooting and maximize the effect of the camera's low-noise capabilities.
Casio EX-F1 Auto Noise Scores

White Balance (5.08)
The actual color of light varies widely depending on the source. While our sophisticated brains do a wonderful job adjusting for this, perceiving essentially white light in all but the most extreme conditions, our cameras have a much harder time. They need to both accurately meter the color of incoming light and digitally adjust that value so that, in the final image, the scene looks the way we remember after mentally compensating for off-hues in the lighting. Not easy, and important to test. That's why we shoot under a variety of lighting conditions, including fluorescents, tungsten (i.e., light bulbs), photo flash and shaded daylight. In addition to automatically adjusting white to lighting conditions, most cameras offer preset white balance settings for a variety of sources, so the photographer can manually adjust when the automatic system doesn't seem to be producing accurate results. In the case of the EX-F1, the number of white balance presets is limited to six, and doesn't include a setting for flash (though it does accommodate two types of fluorescent bulbs). As a result, we tested manual white balance on three instead of our usual four parameters.

Auto White Balance (4.21)
We shot the Gregtag Macbeth color test chart under four types of illumination with the EX-F1 set to automatic white balance and ran the results through Imatest, which produced the chart below. It's important to note that the images shown here display intentionally exaggerated differences in white balance, to demonstrate the type of color shift you'd experience rather than the degree of color shift in real-world images.


   Exaggerated White Balance Errors


Auto WB - Flash Illumination 

  
Auto WB - Fluorescent Illumination 


Auto WB - Daylight illumination

 
Auto WB - Tungsten illumination 

The results here are a mixed bag. Under shaded daylight the automatic white balance delivers very good results (nearly identical to those using the manual preset, in fact). While fluorescent lighting proved difficult for the camera overall, the auto setting actually produced better results than either of the preset options. The auto white balance system didn't respond well to tungsten lighting, though, which represents a problem when shooting indoors with the EX-F1 under common household illumination.

Preset (5.96)
Shooting the same color chart under the same lighting conditions, but using the camera's preset white balance values produced varied results. Using the preset dramatically improved performance under tungsten illumination – indoor shots will look noticeably better if you take the time to make this manual adjustment. Daylight shade results were virtually unchanged, which means they're pretty good with either auto of manual settings. And, as mentioned above, fluorescent lighting baffles both the manual and automatic white balance systems.

   Exaggerated White Balance Errors (Presets)


Florescent Preset WB - Fluorescent Illumination 


  Cloudy Daylight preset WB - Daylight illumination


Tungsten preset WB - Tungsten illumination

Still Life
To provide a side-by-side comparison of image quality, we shoot the same two still life scenes for each camera review. These photos are taken under standard fluorescent lighting with all camera adjustments set to automatic, at a range of ISO settings. The images of our happy (if somewhat stiff) married couple and a colorful still life below are clickable to open the full-resolution originals. These are multi-megabyte files, though, so they can take a while to download.

 ISO 100 



 ISO 200

 ISO 400 

 ISO 800

 ISO 1600 

Low Light (5.60)
Flash photography is a great advance over no photography at all in the dark, but it has its antisocial aspects – aggravated party guests, crying babies – and the harsh illumination produced by on-camera flash often leads to the undesirable deer-in-the-headlights motif. That's why available-light photography is so important, and why we test a camera's low-light capabilities extensively. Low-light performance is also an important differentiating factor when comparing competing cameras head-to-head in today's market. Everybody has gotten better at shooting in low light, but some manufacturers have succeeded far more than others.

We perform two different types of low-light testing, one where the level of lighting is the variable, the other where exposure time starts at one second and stretches out to 30 seconds. The EX-F1 wasn't entirely accommodating on this last one, since the shutter speeds topped out at a modest 8 seconds with the camera set to ISO 400. While the shutter speed range actually stretches out to 60 seconds, the EX-F1 limits the exposure length based on ISO, throttling down the time as you boost the ISO – presumably because noise levels in long-exposure high-ISO shots would be unacceptable, though that’s only an assumption.

In our first test we set the camera to ISO 1600 (the highest available speed for the EX-F1) and varied light levels in our lab from a high of 60 lux (about what you'd find in a normal household environment) down to 5 lux (roughly the illumination from a single candle).

Low Light Tests 

60 Lux

30 Lux 



15 Lux 

5 Lux




As shown in the chart above, the EX-F1 did well in our low-light testing considering its small sensor size, maintaining consistent exposure throughout the range of lighting condtions without gross color errors. Noise did climb as the lights dimmed, as expected, but the EX-F1 performance was in line with other point-and-shoot cameras we've tested.

To assess the camera's performance during long exposures we set the ISO to 400 and increase the shutter speed in increments till we reach 30 seconds, then analyze the camera's noise performance across this range. As mentioned above, the EX-F1 shutter speed range stopped at 8 seconds at ISO 400, so we shot three groups of test shots, at 1 second, 5 seconds and 8 seconds. This produced a flat response at an average noise value just over .835 percent, which is a good result, as might be expected given the camera's noteworthy performance in our other image noise testing.

Casio EX-F1 Long-Exposure Noise


Overall low-light performance for the EX-F1 was slightly lower than some other point-and-shoot cameras we've tested, but not enough to produce differences that would be readily visible to the naked eye in real-world situations.

Casio EX-F1 Low Light Scores

Dynamic Range (7.13)
The EX-F1 did well in our dynamic range testing, particularly at the lower end of the ISO spectrum. There was a steep decline as we reached the ISO 400 level, but that deterioration leveled off well to produce respectably consistent results through the rest of the light sensitivity range.

Casio EX-F1 Dynamic Range


The EX-F1 tested well versus other ultra-zooms, posting a significantly higher score, though it doesn't measure up to the performance of the Rebel XSi SLR.

Casio EX-F1 Dynamic Range Scores

 

Speed/Timing
All speed tests for the EX-F1 were conducted using an 8GB SanDisk Extreme III SDHC card, shooting at the camera's top resolution and quality settings. To accomplish its extremely fast burst rate performance, the EX-F1 stores images first to internal memory, then asks user permission before storing the files to memory card.
 
Startup to First Shot (0)
Considering its speed-demon reputation, this test proved something of a shocker. Turns out the time required to turn on the camera and get your first shot was far slower than other cameras we've tested. For example, the Canon Rebel XSi can squeeze off a first shot 0.98 seconds after hitting the power button, while the Canon PowerShot S5 IS takes 1.7 seconds. The EX-F1, on the other hand, requires several seconds to shake off the cobwebs after power-up before you can depress the shutter – on average in our testing, nearly 3.8 seconds. That may not sound like a lot, but when you grab the camera to capture baby's first step, you expect it to spring to life more quickly than this.

Shot-to-Shot (14.00)
This is where the EX-F1 blows every other camera on the market, SLR or point-and-shoot, out of the water. In the lab it precisely lived up to its claim of 60 full-resolution frames per second (just a hair under 61, in fact). And while the occasions when shooting 60 frames in a single second are few and far between in most of our lives, you can set the interval between frames to suit your needs. We found that shooting swimming birds at 5 frames per second was a great way to capture just the right angle, while ramping up to 20 frames per second worked well when shooting sports action.

Shutter-Shot (3.76)
Aggravating delays between the moment you press the shutter and the moment the camera takes a picture are a rarity today. Surprisingly, though, the EX-F1 did not match the competition when tested in single-shot mode. The Canon XSi, for example, can squeeze off a shot with a delay of less than 0.2 seconds. For the EX-F1, we consistently measured the delay at over 0.5 seconds. While half a second isn't an eternity, it is long enough to miss a photo opportunity. The EX-F1 does have a workaround available in its prerecord continuous shutter mode. By holding the shutter down halfway in this mode, the camera shoots continuously and stores the results in a buffer. When you finally depress the shutter all the way, the prerecorded images along with those taken after you press the shutter are saved. Prerecord is undoubtedly a useful capability but it really doesn't make up for the lack of instant response in basic picture-taking operations.

Processing (8.24)
Digital cameras have a lot of work to do very quickly after you press the shutter, adjusting the raw data from the image sensor to reflect the settings you (or the camera’s automatic systems) have selected, running noise reduction algorithms, storing the resulting data to memory, and getting ready to take another shot. While all that’s going on, of course, you’re left looking at the LCD screen waiting to see how your shot turned out. We measure this processing time using a stopwatch program through repeated test runs. The EX-F1 performed respectably if not exceptionally well here, with an average processing time of just over a second.

Video Performance (8.43)
The score for the EX-F1 in this section is based on our standard lab testing suite, which measures color and resolution data with video taken at standard definition (in this case, 640 x 480). This multi-talented camera also shoots high-definition video in two formats, and high-speed video at three settings. We’ll discuss these separately, but they are not reflected in the numerical score.

Bright indoor light – 3000 Lux
This test involves shooting a test chart in a brightly lit lab environment, then analyzing the resulting video for color accuracy and image noise. The EX-F1 did well here, reproducing most colors well while producing the low-noise video we expect when there’s plenty of illumination.



Video color results at 300 lux


Low light – 30 Lux
A light level of 30 lux is still bright enough to read by, but not enough to produce flawless video reproduction even with dedicated camcorders. The EX-F1 held its own on this test, demonstrating the expected deterioration in color accuracy but maintaining a lower noise level than we typically find with still cameras in video mode.


Video color results at 30 lux

Resolution
Another component test in determining the overall video performance score requires testing the resolution displayed in multiple frame grabs from a test chart shooting. The EX-F1 stumbles here, failing to achieve adequate sharpness even with a well-lit chart. There is artifacting around the edges of objects, and stair-stepping visible on hard diagonal edges of objects in the frame.

Motion
The motion part of our test suite involves shooting a variety of fast- and slow-moving subjects and judging how accurately the video captures these diverse situations. While the EX-F1 results lack sharpness, this seems to be the fault of its resolution performance rather than being tied to the movement of objects in the frame.

High-Speed Video
It’s tough to pass judgement on the quality of video that you wouldn’t otherwise be able to shoot at all.  At 300 fps, video resolution is 512 x 384; at 600 fps, it’s 432 x 192, and at 1200 fps your window is just 336 x 96. From a pure quality perspective, we’re in the range of point-and-grab cellphone video. Focus is another factor that cuts into high-speed video quality: the EX-F1 has trouble with auto focus in the first place and, once you’ve started shooting, the focus is locked. Multiple trials did produce some interesting results (see ourYouTube video of high-speed hijinks below), but it’s novelty, not video quality, that makes it worthwhile.

High-Definition Video
Our biggest cause for concern with the high-def video we shot wasn’t with quality, but compatibility. When played directly from the camera on a 1080p plasma TV, though an HDMI cable, it looks very good, with nice sharpness and well-saturated colors. We’ve seen better quality from dedicated HD camcorders, but you can certainly impress an audience by playing your EX-F1 high-def video on a big-screen set.

Unfortunately, what you can barely do is edit your HD video on a computer, or even watch it on a PC or Mac. The Arcsoft software suite included with the camera offers Windows-based viewing of EX-F1 high-def video and rudimentary editing, but QuickTime, iMovie, Final Cut and other industry-standard programs refused to open the files we transferred to the hard drives of a Mac and a PC. Home video you shoot today is supposed to entertain you for years to come. If the file is non-standard to the degree these are, they fail the important test of time.

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