Editors' note: The competitive landscape for this camera has changed since our review, and we've updated the text and ratings to reflect that. After looking at subsequent reviews we've decided that we were overly forgiving of the color inaccuracy problems in the K20D's photos; given the increase in the number of competitors at the K20D's price, which produce more consistent, high-quality photos, we've dropped the image quality rating from 8 to 7. Text changes include comparisons to newer models.
In case you haven't been paying close attention to the digital SLR market lately, there's been a shift toward CMOS sensors. Though Pentax has stuck with CCD for its entry-level K200D SLR, they have moved to a 14.6-megapixel CMOS chip in their new flagship K20D. That puts it ahead of some more expensive models in terms of pixel count. Notably, Canon's similarly priced EOS 40D sports a 10.1MP sensor, Sony's Alpha DSLR-A700 includes a 12.24MP chip, and Nikon's D90 checks in at 12.3 megapixels. As I always say, megapixels aren't everything, so let's see what else Pentax's K20D has going on.
The overall body design is essentially the same as the K10D's. In fact, they both use the same vertical grip. Pentax did upgrade the LCD to a 2.7-inch screen from a 2.5-inch display. The only other change to the body design is the addition of a PC terminal, which lets you connect the camera to a studio strobe. I was surprised that the K10D didn't have one, so it's nice to see it here, though I'm not sure how many people will really take advantage of it.
The similarity between the two bodies is a good thing. I always liked the K10D's design. It's on the small side compared with a lot of midlevel SLRs, making it easier to carry with you. There are two wheels--one near your thumb and one near your forefinger--to adjust shutter speed and aperture in manual exposure mode. This is much more convenient than the single-shell-plus-button-press system employed by most entry-level dSLRs. Pentax also includes plenty of switch and button controls for various functions, so you don't have to delve into the menus to change most of the functions you use while shooting. I came to really like the AF switch, which is on the left front of the body just behind the lens mount. It's a three-way switch with manual focus on the bottom and single-shot AF on top, which made it easy to change to manual focus when I wanted to override autofocus in favor of a more artistic, selective focus. A handful of controls are hidden in the function menu, but with the four-way rocker, these are still only a few button presses away.
Like its less expensive cousin, K200D, the K20D includes weather sealing, though, as you'd expect, this camera's sealing is more intense. The K20D has 72 rubber seals in its little body to keep out moisture and dust. For example, if you open the battery compartment door, you'll notice the small O-ring around the rim of the door. Speaking of batteries, the K20D's 1620mAh lithium ion rechargeable battery will give you up to 530 shots per charge when using the flash for 50 percent of those shots, though that climbs to 740 shots per charge if you don't use the flash at all. Of course, that doesn't compare terribly well with the 40D's rating of 800 images with 50 percent flash or 1,100 without.
One of the niftier shooting modes Pentax includes is the Sensitivity-priority mode, which lets you select the ISO sensitivity you want while the camera selects the shutter speed and aperture you need based on your selection. This is useful if you know you have to raise the ISO to get a fast-enough shutter speed to freeze a subject that's in motion, but want to keep the ISO as low as possible. Even if you have the Fn menu set to select ISO in full stop increments, Sensitivity-priority mode offers 1/3-stop increments, so you can quickly get a finer sensitivity scale if needed.
Keeping up with the dSLR trends for this year, Pentax includes an Enhanced Dynamic Range mode, which tweaks the tone curve to eke out some extra detail in the highlights of an image. It's a subtle effect, but it does work. The K20D's version is a bit more subtle than Canon's Highlight Tone Priority--at least the version I saw in the 1Ds Mark III-- though that camera is an unfair comparison, to say the least. Olympus also offers a similar type of feature that they call Shadow Adjustment Technology, though they group it with metering modes, while Pentax puts it in the ISO section of the Fn menu. Sony's Dynamic Range Optimizer and Nikon's D-Lighting also work to eke out detail in the darkest and the brightest portions of images, though they function more as software-type adjustments made to images after capture, rather than during capture.
Like all of Pentax's current dSLRs, the K20D accepts the company's K-mount lenses. One of the nice things about Pentax's K lens system is that you can use the vast majority of the lenses the company has made with the K20D. If you're willing to buy an adapter on eBay (I'd stick to the official Pentax-made adapters if I were you), you can even use screw mount (aka M42) lenses dating back to the 1960s. Not too long ago, I found a very nice 28mm f/3.5 screw mount lens on eBay for about $100. I have to focus manually when I use it, since it wasn't made for autofocus, but it's a nice bargain if you can deal with that limitation and given the differences in lens coatings over the years, it can be a fun way to give your shots a slightly different look.