Pentax K-S2 review

We're big fans of Pentax's recent consumer SLRs. They've lacked the latest features such as articulated touchscreens and Wi-Fi, but instead Pentax has gone for large optical viewfinders, elegant controls, weather-sealed bodies and fast performance. They're priced to compete with the likes of the Nikon D5500 and Canon EOS 750D,  but their features are more in line with upmarket cameras such as the Nikon D7200 and Canon 70D. 

The K-S2 is the latest generation of this series, and Pentax is finally catching up with some modern trends. HDMI makes a long-awaited appearance, as does Wi-Fi. The 3in screen isn't touch-sensitive but it is articulated. A Selfie mode kicks in when the screen is folded out to face forwards, whereupon photos are taken using the Wi-Fi button rather than the normal shutter button, giving a more comfortable grip of the camera.

All the things we've admired about previous Pentax SLRs are here too. The viewfinder is significantly bigger than on other SLRs at this price, equivalent to 0.63x on a full-frame camera and with 100% coverage. We can't stress enough what a difference this makes to the experience of taking photos.

^ These are photos taken through the optical viewfinders of the Nikon D5500 and Pentax K-S2, and show how much bigger the Pentax's viewfinder is.

There are dual command dials for direct access to aperture and shutter speed. The other controls are superbly designed to put key functions within easy reach. For example, the ISO button not only lets you set the ISO speed manually but also the range of speeds available in Auto ISO mode. Optical stabilisation is built into the sensor so it works with any lens including wide-aperture primes. The camera is weather-sealed and so can be used in rain, mist or situations that are prone to splashes. The same goes for the new kit lens.

This lens is much slimmer than its predecessor, retracting to 41mm when not in use. The lens cap adds a further 7mm, but it's still a remarkably petite SLR at 116mm from lens cap to viewfinder. The lens must be rotated to extend it before use, and we found that this action was a little stiff, but it's a minor complaint. The zoom range is a little shorter than normal at 18-50mm (27-75mm in 35mm-equivalent focal lengths) but we can live with that.

WI-FI

Wi-Fi comes with NFC for automatic configuration with compatible devices. After installing the app on an Android phone (it's also available for iOS devices) we were connected in about five seconds, although sometimes it took much longer.

The app can browse photos stored on the camera and take pictures remotely. The latter includes touch autofocus and a full complement of exposure controls, with the camera automatically entering shutter- or aperture-priority mode when either of those settings is adjusted. Transferring photos proved trickier. We eventually figured out the convoluted sequence of button pushes, but while we could send snaps directly to Facebook, the option to save photos to the device was greyed out. This app reminds us of the early efforts by other manufacturers, with a few kinks still be to ironed out.

ALIASING AND HDR

The 20-megapixel sensor doesn't include an anti-alias (AA) filter, which in theory boosts sharpness but increases the risk of aliasing artefacts such as moiré interference. It's quite common these days, but we've always found both the benefit and drawback hard to spot.

The K-S2 is able to simulate the effect of an AA filter with a small shake of its on-sensor optical stabilisation. There's even a bracket mode that captures three shots with different AA simulation settings. It's an interesting idea but even in direct comparisons the difference was extremely subtle. We could just about see it in hair textures in our studio scene when we went looking for it, but otherwise it was lost on us.

 ^ Without and with anti-alias filtering.

Another function that left us underwhelmed is the HDR mode. Short for High Dynamic Range, this mode captures a couple of frames at different exposure settings and combines them into a single JPEG with a greater range of highlight and shadow detail than would otherwise be possible. It's pretty much standard on digital cameras these days, but the K-S2's implementation produced results that looked gaudy and over-processed.

^ The scene captured with a single exposure. No complaints, although the sky is inevitably over-exposed. (1/320s, f/7.1, ISO 200, 27mm equivalent)

^ The same scene captured in HDR mode.

For creative colour processing, nothing beats shooting in RAW mode and processing on a computer. Pentax makes RAW capture easy with an FX button that's assigned by default to switch to RAW mode for the next photo only. It's also possible to resave the most recent exposure as a RAW file. This is ideal for people who prefer the convenience of JPEGs' smaller file sizes and wider compatibility, but might want to use RAW for the occasional shot with particular artistic merit.

One feature where the K-S2 is lagging behind its rivals is autofocus. There are 11 autofocus points, arranged in a three-by-three grid of cross-type points, plus an additional pair to the left and right. It's not bad but it's not as flexible as the Nikon D5500's 39 points or the Canon 750D's 19. Then again, the Canon EOS 700D only has nine and that didn't stop us giving it a Best Buy award.

Continuous performance has slipped a little, with the 16-megapixel Pentax K-50 delivering 6fps but the 20-megapixel K-S2 only managing 5fps. This slowed further to 4.5fps when continuous autofocus was enabled. It kept going for 30 JPEGs or 10 RAW frames before slowing, which puts it slightly ahead of the D5500. It was extremely quick in normal use, capturing a shot every 0.3 seconds. 1.6 seconds between shots in live view mode is the best result we've seen from a true SLR (not counting Sony's SLT cameras). The EOS 70D with its innovative live view-friendly autofocus system only managed 2.1 seconds.

IMAGE & VIDEO QUALITY

Video mode is the K-S2's weakest area. Details looked distinctly soft compared to the Nikon D5500's output, and a pronounced rolling shutter effect produced skewed geometry in fast-moving scenes. Autofocus is fixed for the duration of clips. Manual exposure control is available but the ISO speed is limited to 3200 and clips at that setting were quite noisy. It's fine for the occasional casual clip but keen videographers should look elsewhere. It's surprising, then, that Pentax has included a microphone socket. We don't envisage it'll see much use.

Our photo tests gave much less cause for concern, but we had some minor reservations here too. The kit lens performed well but handling of dense textures in JPEGs was good rather than great. Noise levels were a little higher than from the D5500 at fast ISO speeds, with some grain and false colour at ISO 6400. We also noticed a tendency to over-expose highlights in high-contrast scenes, possibly due to the relatively course 77-segment metering sensor. The D5500 has a 2,016-pixel metering sensor, making it easier for the camera to identify small areas of highlight in a scene.

Most of these complaints are trivial, though – the poor focus from the D5500's kit lens was much more noticeable. However, it's particularly worthwhile shooting in RAW mode with the K-S2 in order to recover clipped highlights and take advantage of Lightroom's superior noise reduction.

^ Faithful colours and excellent corner-to-corner focus from the kit lens. Fine details in the distant trees is a little vague though. (1/250s, f/7.1, ISO 100, 27mm equivalent)

^ Focus is spot on in this shot, and the metering has done a fine job of handling the highlights and shadows. (1/200s, f/8, ISO 100, 45mm equivalent)

^ Focus is a tad soft here, and the daffodil flowers have been overexposed. (1/125s, f/7.1, ISO 100, 51mm equivalent)

^ These skin tones are overexposed too. (1/125s, f/6.3, ISO 100, 27mm equivalent)

^ We set the ISO speed to 3200 to freeze motion in low light. There's a bit of noise on close inspection but it's an excellent result. (1/250s, f/4.5, ISO 3200, 51mm equivalent)

^ This shot at ISO 6400 isn't so flattering. Skin tones are grainy and the wall and sofa shows some purple and yellow blotches. (1/60s, f/4.5, ISO 6400, 42mm equivalent)

^ This subject matter is more forgiving at ISO 6400 – a decent result. (1/50s, f/4, ISO 6400, 31mm equivalent)

We expect superb image quality from any camera that costs over £500, and so our small concerns – and the basic video mode – keep the K-S2 from top marks. We're being pretty fussy, though. By any normal measure the K-S2 does deliver superb image quality, and it's only by direct comparison with its rivals that we can spot a few places where it could do even better. Arguably, the differences in image quality are insignificant compared to the benefit of the KS-2's big viewfinder, elegant controls and weather sealed design. Its fast performance in live view mode is another major perk for some people. So while it narrowly misses out on full marks, this is a camera that deserves to be hugely successful. If it's not quite your thing then check out our regularly-updated Best Cameras list and buying guide.