For years the Pentax Q system was the lone occupant of the ultra-compact mirrorless camera space. It made some compromises to get there, including an image sensor that was the same size you'd find in a compact camera. The Q-S1 ($399.95, body only) is the latest entry in the series, but it doesn't offer any updates in terms of image quality or performance when compared with the previous-generation Q7 ($299.42 at Amazon) model. In the time since the Q7's release, Panasonic has put a larger Micro Four Thirds sensor into two models, the GM1 ($660.00 at Amazon) and GM5 ($899.99 with lens), and compact cameras with larger 1-inch sensors like the Sony Cyber-shot DSC-RX100 III have hit the market. The Q-S1 does enjoy a cost advantage over these models, even if you buy the $500 kit that's bundled with a zoom lens. But if size isn't an absolute priority, you can get a more capable mirrorless camera for less money.

Design and Features

The Q-S1 ($499.00 at Amazon)  measures 2.3 by 4.1 by 1.3 inches (HWD) without a lens and weighs in at 7.2 ounces. At one point that would have made it the smallest and lightest interchangeable lens camera you could buy, but the Panasonic GM1 (2.2 by 3.9 by 1.2 inches, 7.2 ounces) is just a little bit smaller. The GM1 uses a Micro Four Thirds image sensor, which is more than five times the size of the 1/1.7-inch sensor used by the Q-S1 in terms of surface area. Even the 1-inch image sensor used in a fixed-lens compact camera like the Sony Cyber-shot DSC-RX100 ($369.99 at Dell) is about 2.7 times the size of the Q-S1's image sensor. The RX100 (2.4 by 4 by 1.4 inches, 8.5 ounces) is more pocket friendly thanks to a lens that collapses into its body, but unlike the Q-S1, that lens is permanently fixed to the camera.

The Q-S1 is available in five body colors—black, champagne gold, gunmetal gray, silver, and white. You can get the camera in any of those colors along with the choice of one of eight leatherette coverings (burgundy, canary yellow, carmine red, charcoal black, cream, khaki green, pale pink, and royal blue). The Q7 was also available in multiple colors, but there are some design differences. The Q-S1 has a small round grip on the front of its body, a departure from the more traditional grip used by the Q7. The front infrared remote control sensor is built into this grip.

Despite its compact size, the Q-S1 has a control scheme that appeals to photographers who are used to taking manual control over image capture. The top plate includes a release catch that raises the flash, the power button and playback control, the shutter release, a standard mode dial, and a control dial that can adjust aperture or shutter speed, depending on the shooting mode. The top also houses the hot shoe; it supports an external flash, but there's no electronic viewfinder (EVF) add-on option for the Q system.

On the faceplate you'll find a lens-release button and a control dial with five set positions—one represented by a dot and the rest numbered 1 through 4. The numbered controls activate in-camera art filters by default, but the dial can also be set to adjust image aspect ratio, set the focus method, enable peaking as a manual focus aid, or toggle the neutral density filter if you're shooting with a lens that includes one.

Rear controls include an exposure compensation control button, the Pentax Green button (it is generally used to reset shooting settings in Program mode or center the active focus point), and info and menu buttons. There's a four-way control pad with a center OK button; directional controls adjust the flash settings, ISO, self-timer, and white balance, while pressing OK allows you to move the select the active autofocus point.

The rear display is a 3-inch LCD with 460k-dot LCD. It's unchanged from the Q7, and adequate for framing and reviewing images. But a sharper 920k-dot LCD, like the one you'll find Alpha 6000 ($398.00 at Amazon) , would have been a nice addition, especially if you're using a manual focus lens. The Q system includes several manual focus lenses, including the 05 Toy Telephoto ($79.95 at Amazon) , and K-mount SLR lenses can be used via the Adapter Q for K-Mount Lenses ($199.00 at Amazon) . The image sensor is stabilized, so any lens you attach will benefit from that feature; but if you're attaching a telephoto SLR lens, it's a good idea to use a tripod to assist in framing a shot.

There's no Wi-Fi, which is almost a given in a modern digital camera, especially one costing this much. The Q-S1 seems like a perfect camera for the Instagram crowd; it's small, offers a noticeable advantage over smartphone cameras, and includes baked-in filters and can accept fun toy lenses. You can add an Eyefi Mobi ( at Amazon) memory card to copy images and video clips over to your smartphone, but that's an added expense.

Performance and Conclusions

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The Q-S1 starts and captures an in-focus image in just about 1.7 seconds, which is on the pokey side for a mirrorless camera. The Olympus OM-D E-M10 ($738.00 at Amazon) does the same in just 0.9-second. The Q-S1's slower focus time, 0.4-second on average, certainly plays a part; the E-M10 focuses almost instantly. In very dim light the Q-S1 focus speed slows to 0.9-second.

The Q-S1 doesn't offer any sort of continuous or tracking focus mode, so it's not the best camera to use to photograph subjects that move erratically. The continuous shooting speed varies based on file format; for Raw+JPG it's 1.3fps, for Raw it's 1.5fps, and for JPG it's 5.7fps. Even at those rates, burst shooting is limited; you can only get 3 Raw+JPG, 7 Raw, or 5 JPGs before the camera slows down, and you'll have to wait about 6 seconds for all of the images to write to a memory card. If you want a small camera that can rattle off shots in rapid succession, consider the Sony Cyber-shot DSC-RX100 III ($598.00 at Amazon) , which can shoot at 10fps. It's expensive, but it's the best fixed-lens compact camera we've tested.

I'm reviewing the Q-S1 as a body only, but if you're curious as to how the 02 Standard Zoom ($149.99 at Amazon) performs you can peruse our full review of that lens. We reviewed it along with the Q7, which has the same sensor and image-processing engine as the Q-S1, so expect similar results.

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Imatest also checks photos for noise. The Q-S1 uses a 12-megapixel 1/1.7-inch image sensor, the same type as you'd find in a compact camera like the Nikon Coolpix P7800 ($668.00 at Amazon) . When shooting JPGs at default settings it keeps noise below 1.5 percent through ISO 1600, and shows just 1.6 percent at ISO 3200. Close examination of images from our standard ISO test scene on a calibrated NEC MultiSync PA271W( at Amazon) display tells more than simple numerical scores. Detail is all but gone at ISO 1600; at ISO 800 you can still make out fine lines in our test scene, but just barely. We've included crops from our test sequence in the slideshow that accompanies this review; you can see for yourself how image detail slips bit by bit as you increase the ISO from its base (ISO 100) setting.

The Q-S1 can also capture Raw images in the Adobe standard DNG format. Raw files show more detail, with the lines in our test scene remaining visible through ISO 1600. Raw images are not nearly as blurry at ISO 3200 and ISO 6400, but they do show a lot of noise. You'll have to take some time when processing Raw images and make sure that you correct for distortion. The camera doesn't apply any corrections, and the lenses we've used with the Q system exhibit quite a bit. If you use Lightroom, you can remedy it with a lens profile adjustment, which requires only a single click to activate.

Video is recorded at up to 1080p30 quality in QuickTime format. The footage is sharp and crisp, with accurate colors, but it's not without issue. The rolling shutter effect, which causes the bottom of the frame to advance more quickly than the top, is evident during quick camera movements. And, while the stabilization system does work to steady video, it can give footage an unnatural look when focusing close to your subject and handholding the camera. The built-in microphone is adequate for casual clips, but if you're a bit more serious about video production, look elsewhere; the Q-S1 doesn't include a microphone input port. It does have a proprietary USB connector and micro USB port, both located on the bottom of the camera, a standard SD/SDHC/SDXC memory card slot, and an external battery charger.

The Pentax Q-S1 is an example of the company's unique approach to the mirrorless camera space, but stiffer competition means that the approach has fallen a few steps behind the curve. Q cameras used to offer significant size advantage when compared with other mirrorless camera models, at the cost of sensor size and image quality. Now you've got models with larger 1-inch image sensors (the Samsung NX Mini ($256.91 at Amazon) ) and Micro Four Thirds cameras like the Panasonic GM1 and GM5 available with interchangeable lenses, and compact cameras with wide-aperture zoom lenses and larger 1-inch image sensors like the Canon PowerShot G7 X ($536.00 at Amazon) and Sony Cyber-shot DSC-RX100 III to consider.

All of that adds up to make the Q-S1 a tough sell, especially since it's $500 with a lens, and that the Q7—which, cosmetics aside, is the same camera—is still available at retail for less. If you just want a small camera with the ability to change lenses, either the GM1 or the GM5 is a better choice—but they're a lot more expensive; the GM1 is $750 with a zoom lens and the GM5 is $900 with the same zoom. If you just want a small camera with excellent image quality, you can forgo the interchangeable lenses and opt for the original version of the Sony RX100, which sells for about the same price as the Q-S1, or splurge on the RX100 III. Our favorite mirrorless camera in this price range, the Editors' Choice Sony Alpha 6000, is a bit larger all around and doesn't seem like fair competition to the Q-S1. The Alpha 6000 sells for $650 without a lens, has an SLR-sized APS-C image sensor, and is built for fast shooting thanks to an incredible autofocus system that can track moving objects and rattle off photos at 11.1fps.

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