Pentax K-70 Technical Info

by Mike Tomkins | Posted: 06/09/2016

Sensor

At the core of the Pentax K-70 digital SLR is a brand-new 24.24-megapixel, APS-C sized CMOS image sensor, up from the 20.12-megapixel chip of the K-S2. For the first time in a Pentax camera, the sensor includes on-chip phase-detect autofocus pixels.

Total resolution of the K-70's sensor is 24.78 megapixels. With dimensions of 23.5 x 15.6mm, it's just ever so slightly lower in effective resolution terms than the sensor used in the APS-C flagship Pentax K-3 and K-3 II, but has a fractionally higher total pixel count. (The K-3 siblings share a 24.35-effective / 24.71-total megapixel count.)

Just as in most DSLRs these days, there is no optical low-pass filter in the Pentax K-70. This means that per-pixel sharpness is maximized, but moiré and false color effects could be an issue with certain subjects. However, the presence of Pentax's clever anti-aliasing filter simulation function, first introduced on the K-3 DSLR, means that if you have a problem with moiré or false color you can simply reshoot with the function enabled to avoid the problem.

Raw files shot with the Pentax K-70 have a 14-bit depth as in Pentax's flagship models, rather than the 12-bit depth of Pentax's past entry-level and mid-range models.

Processor

Like the Pentax K-S1 and K-S2 before it, the Pentax K-70 processes its images and movies using a PRIME M II-branded image processor. That's an upgrade from the PRIME M processor featured in the earlier K-30 / K-50 / K-500 DSLRs and K-01 mirrorless camera, but less powerful than the PRIME III processor used in the APS-C flagship K-3 and K-3 II, not to mention the PRIME IV chip used in the full-frame Pentax K-1.

ISO

Surprisingly, the Pentax K-70 bests all of Ricoh's Pentax DSLRs at the APS-C sensor size in terms of ISO sensitivity, on paper at least. Where the company's other current APS-C models have a sensitivity range of ISO 100 to 51,200 equivalents, the K-70 manages a wider ISO 100 to 102,400-equivalent range. And the whole of that range is available by default, with no ISO expansion function needed to access the highest or lowest sensitivity options. An Auto ISO function is also provided.

Burst

Ricoh rates burst performance of the K-70 in continuous mode at 6.0 frames per second, with a burst depth of 40 large/fine JPEG, 10 raw, or nine raw+JPEG frames. By way of comparison, the earlier K-S2 was manufacturer rated just fractionally slower at 5.5 frames per second, with a somewhat lesser burst depth of 30 JPEG or nine raw frames, despite the older model having a ~17% lower total pixel count.

Not surprisingly, though, the K-70 is still eclipsed by the APS-C flagship K-3 II, with burst shooting at a manufacturer-claimed 8.3 frames per second, and a buffer depth of 60 JPEG or 23 raw frames.

Optics

As you'd expect in a Pentax APS-C format DSLR, the K-70 accepts K-mount lenses -- whether intended for a full-frame or APS-C image circle -- thanks to the KAF2 bayonet mount on its front deck. Where some affordable DSLRs opt for a less durable plastic lens mount, the K-S2's mount is crafted from stainless steel.

Both screw-drive lenses and those with internal autofocus motors are accepted, and you can also use older Pentax screw-mount lenses or larger-format 645 and 67 lenses with the appropriate adapters. Pentax's power zoom lenses -- of which there are only a few older models, all long-discontinued -- are supported in most respects, but the power zoom-related functionality won't be operational on this body.

And for the first time, a new KAF4 lens variant is also compatible, allowing for a new aperture control method. Instead of the earlier mechanical aperture coupling, an electromagnetic actuator in the lens itself is used to control the iris. Certain other earlier Pentax DSLRs can also use KAF4 lenses on current firmware, but the K-70 is the first to do so right out of the box. The change should allow for both smoother and quieter aperture control, although the lens wasn't available to test during our review, so we haven't been able to confirm the improvements for ourselves.

Weather sealing

Impressively for an affordable camera like this, the Pentax K-70 is fully weather-sealed, providing a similar level of dust and water-resistance to the flagship K-3 DSLR. There are around one hundred seals throughout the K-70's body, and a healthy selection of weather-sealed lenses and accessories are also available, making this a great choice if you plan on shooting in rainy or dusty environments.

Kit lens

The Pentax K-70 is available either body-only, or with a bundled kit lens. If you choose the kit option, you'll get your K-70 along with the smc Pentax DA 18-135mm f/3.5-5.6 ED AL [IF] DC WR, a versatile travel zoom that should satisfy consumer photographers, even if it's rather soft in the corners wide-open. It's certainly a better option than the smc Pentax DA-L 18-50mm F4-5.6 DC WR RE lens which shipped in the K-S2's kit, as we found that optic to be rather handicapped by its finicky retraction mechanism.

Shake reduction

As you'd expect on a Pentax-branded DSLR, image stabilization is handled in the camera body courtesy of a movable platter on which the image sensor is mounted. The system used in the Pentax K-70 is said to have a 4.5-stop corrective ability to CIPA testing standards.

If you're an astrophotography fan, you'll be pleased to hear that the system works with the Astrotracer function of Pentax's optional O-GPS1 GPS unit, slowly moving the sensor during exposure to prevent star trails from forming during long exposures. It's also used to correct for tilted horizons automatically, and for the aforementioned antialiasing filter simulation function.

Dust removal

It's also used for one more feature, too, although we'd have preferred it not be. Even with the best weather sealing in the world, dust is going to get into your camera during lens changes, so some method of removing dust from the sensor is a must. Unlike higher-end DSLRs -- not to mention the preceding K-S2 -- which use a dedicated piezoelectronic element to shake dust free from the sensor, the -70 instead relies on the sensor shift mechanism to do the same job. That approach is not typically very effective, in our experience, and so we'd suggest having a sensor cleaning kit on standby for those times when some more stubborn dust particles adhere to the sensor cover glass.

Viewfinder

Another relatively unusual feature at this pricepoint -- at least, compared to rivals, as past mid-range Pentax models have been similarly generously specified -- is the inclusion of a glass pentaprism viewfinder with a manufacturer-rated 100% coverage. Compared to the pentamirror finders of most DSLRs at this pricepoint, the K-70's finder should prove noticeably brighter and more accurate.

The Pentax K-70's viewfinder has 0.95x magnification, just as in the K-S1, K-S2, K-3 and K-3 II, and an eyepoint of 22.3mm from the center of the viewfinder lens. A built-in dioptric adjustment is available within a -2.5m to +1.5m^-1 range, and an interchangeable Natural-Bright-Matte III focusing screen is provided.

Note that unlike some competitors, Ricoh hasn't included a proximity sensor adjacent to the viewfinder, so you'll want to disable the LCD monitor manually before raising the camera to your eye.

Articulated LCD

On the rear panel of the Pentax K-70 is a 3.0-inch, 3:2-aspect LCD monitor with a total resolution of around 921,000 dots. It uses an air-gapless design with a resin layer that fills the space between the LCD panel and the cover glass, providing better contrast and lower glare.

As in the K-S2, this LCD monitor is mounted on a side-mounted, tilt/swivel articulation mechanism. This allows it to be seen from most angles -- including in front of the camera itself for selfie shooting -- or to be closed facing inwards towards the camera body for an extra modicum of protection from minor knocks, scrapes and smudges.

The display provides a +/-two-step adjustable outdoor view setting for greater brightness under sunlight. And for night viewing, it provides an unusual Night Vision LCD function which uses only red light, attempting to disturb your night vision as little as possible.

Focus

As in the K-S2 before it, the Pentax K-70 sports a SAFOX X autofocus sensor with a total of 11 autofocus points, of which the central nine points are cross-types that are sensitive to both horizontal and vertical detail. For good performance even in low-light shooting, it's sensitive all the way down to -3EV. A dedicated LED autofocus assist light is also provided.

In continuous-servo mode, you can choose a single point to focus, and then optionally allow the camera to roam to any of eight surrounding points, handy so that you don't lose focus if you slip off your intended subject briefly.

As well as the standalone phase-detect AF sensor, the K-70 also boasts on-chip phase detect pixels on the image sensor, a first for a Pentax camera. These are used in concert with contrast detect algorithms to provide a more responsive hybrid autofocus system, for use either in live view mode or when shooting movies. And thanks to this system, the K-70 is also the first Pentax DSLR to provide full-time autofocus during movie capture. (Continuous AF is however not available for shooting stills in live view mode.)

Exposure and Creative options

The Pentax K-70 is capable of shutter speeds as fast as 1/6,000 second, and meters exposures using a 77-segment multi-pattern metering sensor, just like the K-S2 before it. (The metering sensor has a working range of EV 0 to 22, using a 50mm f/1.4 lens at ISO 100-equivalent.)

Exposure compensation is available within a +/- 5EV range in either 1/3 or 1/2 EV steps. A built-in, popup flash strobe is included in the design, as is a hot shoe for external strobes. Flash sync is at 1/180 second, and flash exposure compensation is within a -2 to +1EV range in 1/3 EV steps.

Exposure modes on offer include Program, Aperture-priority, Shutter-priority and Manual as you'd find on almost any DSLR, although true to Pentax form, they're called P, Av, Tv and M, rather than the more usual P, A, S and M. There are also the usual Pentax-specific modes you'd expect to see present -- Sv (Sensitivity priority) and TAv (Shutter and Aperture priority) -- plus a Bulb position.

Beginners can keep things friendly with both Auto and Scene-mode shooting, the latter providing a selection of 19 scene types, again unchanged from the K-S2. More advanced shooters can recall favorite settings with three User modes, one more than was offered by the K-S2.

The extra User mode offered in the Pentax K-70 replaces the K-S2's Auto HDR mode on the Mode dial, but HDR shooting is still possible through the menu system. If you want to fine-tune the look of your images for creative effect, a total of 13 custom image modes are provided in the K-S2. There are also nine digital filter functions which provide more eyecatching results.

Also available are a Cross Process function, an adjustable +/-four-step Clarity control, and a skin tone correction tool. And of course, you can also have the K-70 automatically correct for lens distortion, vignetting, lateral chromatic aberration and diffraction with first-party lenses, as well as correcting highlights and shadows to reduce the impact of blocking or clipping. You can also look forward to using both an interval timer and multiple exposure function.

Movie

The Pentax K-70 is the company's most video-capable DSLR to date in at least one respect: As we've already mentioned, it's the company's first APS-C camera to provide full-time autofocus during video capture. That's achieved thanks to the new Hybrid autofocus system, coupling both on-chip phase-detect pixels and contrast-detect algorithms operating on the image data.

There's still no native 4K capture, though, with the K-70 instead able to record Full HD (1,920 x 1,080 pixel) video at rates of 30, 25, or 24 frames per second using MPEG-4 AVC / H.264 compression. Unlike the K-S2, it also allows shooting at 60 or 50 interlaced fields per second, but it's not immediately clear if this is still operating on 30 fps sensor data, or if the interlaced mode is captured at a higher rate. Of course, if you prefer to trade off some resolution for a higher frame rate, rates of 50 or 60 frames per second are alternately available at HD (1,280 x 720 pixel) resolution.

And while it can't record 4K ultra-high def movies ordinarily, the Pentax K-70 is able to create 4K time-lapse movies in-camera. It also offers an unusual "Star Stream" movie mode, which merges multiple frames to create moving star trails in your final video.

Movies other than 4K interval and star stream types include stereo audio, either from a built-in stereo mic or a 3.5mm microphone jack in the left side of the camera body, a relatively unusual option in an affordable DSLR.

Wi-Fi (but no NFC)

The Pentax K-S2 was the company's first DSLR to include in-camera Wi-Fi wireless networking connectivity, a feature that's retained for the followup K-70. What isn't retained is the NFC function, a decision which will have no impact whatsoever on iOS users (since Apple steadfastly refuses to let third parties use the NFC radios in its phones), but it's rather a shame for Android folks. The NFC antenna in the K-S2 made pairing much quicker and easier; Pentax K-70 users will need to pair manually instead.

Through a free "Image Sync" app for both Android and iOS smartphones and tablets, the K-70 can be controlled remotely, complete with a live view feed and the ability to adjust variables such as shutter speed, aperture and ISO sensitivity. It's a much more integrated solution than in Pentax DSLRs prior to the K-S2, which at best have offered compatibility with Eye-Fi cards for image transfer, or with Pentax-branded Flucards for image transfer and remote control.

Connectivity

Wired connectivity in the K-70 includes USB 2.0 High Speed data, a Type-D Micro HDMI high-definition video output, and the aforementioned 3.5mm microphone jack and flash hot shoe. The microphone jack doubles as an input for an optional CS-310 cabled remote release.

Storage

Images and movies are stored on Secure Digital cards, courtesy of a single SD card slot that is compatible with SDHC, SDXC and UHS-I cards.

Both Pentax's proprietary PEF raw format and Adobe's standardized DNG raw format are supported in-camera. As mentioned previously, the K-70 now supports 14-bit raw capture, a step up from the 12-bit raws of its predecessor.

Power

Power comes courtesy of a proprietary D-LI109 lithium-ion battery pack, the same type used in the earlier Pentax K-S2, K-S1 and K-50, among others. Battery life is rated at 410 shots on a charge to CIPA testing standards, unchanged from the earlier cameras. Like the K-S2 before it, the Pentax K-S2 is no longer compatible with AA batteries, so you'll want to look to the earlier K-50 instead if you need support for these in the camera body. (And the K-3 / K-3 II can also accept AA batteries courtesy of their optional portrait / battery grip.)