Pentax ist DS

The Pentax ist DS is Pentax’s second digital SLR, a successor to the well-received Pentax ist. Priced at $899, the ist DS is substantially smaller than its predecessor, and offers improvements in buffer size and file-writing speed that help the camera’s overall performance. While the camera packs a good assortment of features, evaluating its image quality is a little trickier. (And figuring out how to pronounce its name is another challenge.)

Build and Weight

The ist DS is very small and extremely light for an SLR. Though the ist has a plastic enclosure, it has a very sturdy feel with no creaking or squishing.

The camera is comfortable enough to hold, but the small size can be a problem if you have medium to large hands. Because there’s very little space between the hand grip and the lens body, the fingers of your right hand can get a little crowded while shooting, especially if you’re wearing gloves.

In addition, the left side of the camera is so short that it can’t easily rest against your left hand, which makes it harder to stabilize while shooting. Having a smaller, lighter camera is great when it’s in a bag on your shoulder, but when shooting, sometimes a little extra size is easier to hold. Though the ist DS is light, it’s no so light as to cause image-stability problems.

The ist DS supports the Pentax KAF2, KAF, and KA mount lenses, as well as older screw-mount lenses and 67/645 lenses (via special adapters). As with other digital SLRs, you must apply a multiplication factor to any lens you attach to the ist DS to determine its equivalent 35mm focal length. The ist DS has a 1.5x multiplication factor.

The ist DS does not use a proprietary battery system. Instead, you can power the camera with either four AA cells or two CR-V3 lithium batteries. Though AAs are convenient, the ist DS devours alkaline batteries very quickly, and rechargeable ones don’t fare much better. By contrast, CR-V3 lithium batteries last as long as any proprietary battery, but are certainly more difficult to find than AAs. In the end, we would have preferred a proprietary rechargeable battery of some kind.

Control and Interface

Just from looking at the ist DS, you might assume it lacks features. While many SLRs are riddled with buttons and dials, the ist DS has a very small number of controls. A status display sits on top of the camera, while a back-mounted 2-inch color LCD provides image review and menu access. Unfortunately, the top-mounted status display has no backlight, making shooting in the dark extremely difficult.

There are no buttons on the camera that directly alter settings—you change all settings using an in-camera menu displayed on the rear LCD screen. To set white balance, ISO, flash mode or drive mode, you press a function button to activate a menu, and then use a four-way navigation rocker on the back of the camera to navigate to the desired setting.

The advantage to this completely menu-based scheme is that you won’t be accidentally changing any settings by bumping the controls. The downside is that it takes just a few more button presses to set most primary settings than it does with cameras that have buttons dedicated to these functions.

Secondary settings such as image size and compression, autobracketing, and image settings such as Saturation, Sharpness, and Contrast are all accessed through a separate menu.

Though the ist DS lacks some of the secondary features found in its competitors, such as white-balance bracketing, it includes all of the important features you’ll need, such as flash exposure compensation, autobracketing, and a good selection of metering modes.

Shooting

Despite our complaints of small size, shooting with the ist DS is very enjoyable thanks to its sturdy feel and peppy performance. The camera may be small, but its viewfinder is surprisingly large—bigger than the Canon EOS Digital Rebel XT’s, and noticeably brighter.

The ist DS uses an 11-point autofocus system with illuminated focus points inside the viewfinder. There’s no way to manually select a focus point while shooting, but otherwise we were very impressed with the camera’s focusing. Even in low light, the ist DS did a speedy job of achieving accurate focus.

To select exposure compensation, you press a small button just behind the shutter release while turning a control wheel on the back of the camera. The camera’s power control is a swiveling switch that surrounds the shutter-release button. In addition to On and Off positions, an additional spring-loaded position provides a depth-of-field preview. I really liked this control and found it much easier to use than the usual “button located somewhere near the bottom of the camera” that most SLRs employ.

I was disappointed to find that the ist DS lacks any sort of control for automatically cycling through reciprocal exposures, an exceptionally useful feature included on many other SLRs.

Image buffering and writing is very speedy and well-managed. The camera’s burst speed is a somewhat pokey 2.8 frames per second, but the camera can buffer 8 frames before it has to start writing images to its Secure Digital (SD) card. After that, shooting slows down, but the camera still manages a respectable frame rate while continuing to write.

Perhaps the most frustrating feature of this camera is its baseline ISO of 200. While most cameras start at 100 and go up from there, the ist DS starts at 200, an ideal speed for many daytime indoor shots, but is somewhat limiting when shooting outdoors in bright sunlight.

Image Quality

Image quality is a mixed bag on the ist DS. Simply put: if you’re shooting in Raw mode, the camera takes very nice images with excellent detail, good color rendition and dynamic range. If you’re shooting in JPEG mode, you’re not going to fare as well. The camera’s internal processing yields JPEG images with very weak detail, and that by default are oversaturated and too high-contrast. You can reduce the saturation and contrast using simple in-camera options, but there’s really nothing to be done for the sharpness problem.

Because this camera is positioned as a “starter” SLR, most people will probably be shooting in JPEG mode. Consequently, its poor JPEG performance is a serious problem.

Macworld’s Buying Advice

The ist DS is a well-made, attractive camera that’s comfortable to shoot with and offers a competitive feature list and interface. Though it’s capable of producing very good images, its weaker JPEG performance is frustrating. If you’re looking for a small, lightweight camera, the ist DS is a good candidate. And if you’re looking for a digital SLR and already have Pentax lenses, this camera is hands-down the choice for you.

[ Ben Long is the author of Complete Digital Photography , 3rd Edition (Charles River Books, 2004). ]