Pentax X90: Performance

PERFORMANCE
Pentax reports increased battery life and a 30fps, 720p HD video mode in the X90, and these should hopefully address a couple of the oft-repeated gripes about the X70. As to the reports of speed of operation, read on.

Shooting Performance
The X90 displayed a focus point about 1.6 seconds after power on, and I was able to get off a first shot in about 2.5 seconds. Single shot-to-shot times ran about 2.25 seconds. Shutter lag came in at 0.01 seconds and AF acquisition time at wide angle was 0.43 seconds - both of these figures are among the best times we've observed for superzoom class cameras, and the AF time is a noticeable improvement over the 0.82 seconds we measured for the X70. AF acquisition time gets slower at telephoto, a common occurrence in the class, but the X90 seems among the slower cameras in this respect. A focus assist lamp may be enabled via internal menu to help with AF in dim light.

Shutter Lag (press-to-capture, pre-focused)

AF Acquisition (press-to-capture, no pre-focus)

Continuous Shooting

* Note: Continuous shooting framerates are based on the camera's fastest full-resolution JPEG continuous shooting mode, using the fastest media type available (300x CF, SDHC, etc.). "Frames" notes the number of captures recorded per burst before the camera stops/slows to clear the buffer.

Continuous shooting rates at full resolution ran about 1.4 fps, but the X90 is a bit difficult to use in this mode with fast moving subjects. There's about a one second blackout of the monitor or EVF after the first shot in continuous mode, and then a slight delay before each subsequent image is displayed, so keeping the camera on the subject can be a job, particularly if you're zoomed in close and the subject is tending to fill the frame. There are low, medium and high speed shooting options at 5 megapixel resolution that offer frame rates up to 10 fps, but the monitor and EVF go blank while shooting the entire burst so tracking can really become a chore.

The X90 has "triple shake reduction" stabilization - CCD shift and high ISO adjustment for still images and an electronic movie shake reduction setting. I shot most of the images for this review with the X90 mounted on a monopod, and would recommend some sort of camera support for anyone who expects to be shooting a lot toward the telephoto end of the focal range. Pentax claims up to a 3 stop advantage for the stabilization system of the X90, which in theory would allow you to hand hold the camera with shutter speeds in the 1/80th of a second range at maximum telephoto and still keep camera shake from negatively impacting image quality. Sounds good in theory, but it's not easy to do for real, and any ultrazoom being shot at the telephoto end would benefit from some additional support to help minimize shake.

At auto ISO, Pentax rates the X90 flash for a range out to almost 30 feet at wide angle, or about 16.7 feet at telephoto. Flash recycle times with a 2/3 full battery were about 4.25 seconds for a partial discharge and about 6.5 seconds for a full discharge. Exposure was good with flash at the shorter distances - the flash didn't tend to overpower the subject.

Battery life for the X90 is rated at about 255 shots, up from 170 in the X70.

Lens Performance
The X90's 26x zoom goes from a fast f/2.8 maximum aperture at wide angle to f/5 at telephoto - right in the ballpark with the leaders in the class. The lens looked to be free of geometric distortion at wide angle, with just the slightest hint of pincushion at telephoto. Corners and edges were a bit soft at wide angle; telephoto showed some soft corners and edges as well. There seemed to be some light falloff in the corners of some shots with the lens zoomed to 250 mm and up (35mm equivalent). Notice the slightly darker corners in the shot of USS Lake Champlain's bow:

There was chromic aberration (purple fringing) in some high contrast shots at both the wide and telephoto ends of the lens, but the effect was more dramatic at telephoto - a few images showed purple at 100% enlargement, such as this worst case tree and bright sky.

The lens can focus as close as about 3.94 inches in macro mode, and 0.394 inches in "1 cm macro" mode.