Pentax *ist DL

Color (7.19)
The Pentax *ist DL packs an interline interlace 23.5 x 15.7 mm CCD with a primary color filter. This prosumer digital SLR can shoot 8 bit color in JPEG format and 12 bit in RAW. We tested how accurate those colors are by taking several exposures of the industry standard GretagMacbeth color chart. After uploading the images into Imatest Imaging Software, we analyzed the data and output charts to see how close the *ist DL’s colors come to reality. Below is a modified chart with the inner rectangle representing the chart’s true color, the inner square showing the color-corrected hue, and the outer square showing the Pentax’s depicted colors.

If all those colors look the same to you, check out this next chart – and get your eyes checked. The same results are shown with the squares representing the ideal colors from the original chart and the circles representing what the *ist DL produced. The farther those two shapes are from each other, the more inaccurate that particular color is.

The Pentax *ist DL offered an average performance with a lackluster 7.19 overall color score. While this would be decent for a compact digital camera, this is a little disappointing for an SLR. Even more disappointing is the tendency for the *ist DL to over-saturate colors by about 24.3 percent. This really makes the reds and pinks stand out, which may look good in portraits but will look strange in most other situations. This digital camera had a mean color error of 8.31, which isn’t terrible but isn’t typical of a pricey SLR either.

Still Life Scene
Below is the classic DigitalCameraInfo.com still life scene shot by the Pentax *ist DL.

Click on the image above to view a full-resolution picture, but beware of the large linked file.

Resolution / Sharpness (4.1)
Pentax advertises 6.31 total megapixels on its CCD, with 6.1 of them effective in taking images. To test this out, we take several pictures of an industry standard resolution chart. We upload those images into Imatest to analyze their sharpness and to see how many pixels each picture is actually composed of. Many times the advertised count is a lot higher than what we actually find in the image files. In fact, if a camera comes within 70 percent of its advertised effective pixel count, we give it a "good" designation. A "very good" designation goes to cameras that use above 80 percent and "excellent" is for those that use above 90 percent.

Click on the chart above to view full res image

Most digital SLRs perform well at this test because they usually pack high quality image sensors. However, the Pentax *ist DL didn’t live up to the DSLR standard. It recorded 4.1 megapixels, which is only 68 percent of its advertised count. This doesn’t necessarily mean that the pictures will look pixillated; it only means that users should be mindful when cropping and enlarging photographs from this model. The high quality JPEG shot with the *ist DL is over-sharpened by 18.39 percent, which is not too bad. In general, less in-camera sharpening is better, as users should be able to take this step later in photo editing software.

The reported resolution test results were based off a JPEG image captured with the *ist DL at f/9.5 at 55mm, using the kit lens.

Noise – Auto ISO (9.37)
The Pentax *ist DL has an interesting feature that lets the user set the top automatic ISO range, so instead of a broad 200-3200 range, users can choose a narrower range of 200-400 and then let the camera automatically choose between the two. This system proved efficient, with a 9.37 overall automatic ISO noise score. This is an impressive score for any digital camera.

Noise – Manual ISO (12.09)
This DSLR performed even better when we manually adjusted the ISO sensitivity. The noise levels remained fairly low, even for a digital SLR. Below is a chart with the Pentax *ist DL’s ISO ratings on the horizontal axis and the noise levels on the vertical axis.

This Pentax fared better than the Canon Rebel XT, which did quite well itself in terms of noise suppression. The *ist DL scored an overall manual ISO noise score of 12.09, higher than the XT’s 11.53. It should be taken into account that the Rebel does have more pixels than the *ist DL, in a slightly smaller body. The Pentax *ist DL also provides an extra ISO rating of 3200.

Low Light Performance (5.5)
In theory, any digital camera with a 3200 ISO rating and low noise scores should also perform well in low light. We tested the *ist DL by shooting exposures of the color chart at decreasing light levels of 60, 30, 15, and 5 lux. 60 lux is about what your living room looks like at night with only two table lamps on. 30 lux is the equivalent of a single 40-watt bulb. 15 lux is about what you’d find in a broom closet with lighting coming from a hallway far, far away. 5 lux is almost total darkness.

The *ist DL was difficult to manipulate in low light. First, there were issues with the manual white balance. It had a really hard time measuring it and would read "no good" much of the time. When it did manually calibrate the white balance, it wasn’t consistent or accurate, so we tested the camera’s low light capabilities using the tungsten white balance mode. The second problem was the focus. As you can see, this Pentax has problems focusing in low light. The third problem is the color. The darker the surrounding light got, the more everything took on an overall bluish tint. All of the low light shots are splotchy and look like a cross between modern pop art and a Georges Seurat painting.

Speed / Timing
Start-up to First Shot (9.26)
The Pentax *ist DL powered up and took its first shot in 0.74 seconds, which is better than a compact digital camera but slower than most SLRs. Most compact cameras take about three seconds and most SLRs take about a tenth of a second. If this model aims to be the bridge between the two, then it succeeded with its start-up time right in between the two types.

Shot to Shot Time (9.2)
Other than Olympus’ E-300, the *ist DL must be one of the slower SLRs with an unimpressive burst mode. It takes 0.8 seconds between shots in the regular burst mode. In the First Four mode, it takes a picture at an average of every 0.58 seconds. In the Last Four mode, it takes one at an average of every 1.1 seconds.

Shutter to Shot Time (8.78)
The shutter lag in this model was a bit disappointing at 0.11 seconds. Most SLRs hardly have any, so even this fraction of a second is something to be frowned upon.