Pentax K-3 Technical Info

by Mike Tomkins | Posted: 10/07/2013

Sensor. The Pentax K-3 is now based around a 24.35-megapixel image sensor, up from the 16.3-megapixel chip used in the K-5, K-5 II, and K-5 IIs. With 50% more pixels, the new chip theoretically yields around a 22% increase in linear resolution. Maximum image size is 6016 x 4000 pixels.

The new sensor is still a CMOS chip with Bayer RGBG filter array, but it's fractionally smaller than the previous generation. Dimensions are 23.5 x 15.6mm, down from 23.7 x 15.7mm. Total resolution is 24.71 megapixels, well above the 16.9 megapixels of the previous-gen chip.

As in the Pentax K-5 IIs, the Pentax K-3 doesn't include an optical low-pass filter. It does, however, add an on-demand mechanical antialiasing function. More on that in a moment. (Or read the "Geek's Guide to On-Demand Low-Pass Filtering" by IR publisher Dave Etchells, for the full story.)

Processor. Also brand-new for the Pentax K-3 is a next-generation of Pentax's image processor, now dubbed PRIME III. (That's a contraction of "Pentax Real IMage Engine", if you're curious.)

The PRIME III processor replaces the PRIME II chip used in the majority of Pentax K-mount cameras since the K-7 launched way back in 2009, with only the K-30, K-50, and K-500 DSLRs and K-01 mirrorless using the intermediate PRIME M processor. The change, then, is pretty big news.

According to Pentax, the new PRIME III chip allows it to deliver improved noise reduction processing, and cleaner images. It also provides for improved performance, as we'll see in a moment. Another nice feature is that it can handle H.264 video compression, as did the earlier PRIME M chip. That means that -- unlike PRIME II cameras -- Pentax is no longer limited to inefficient Motion JPEG compression in the K-3.

Sensitivity. Compared to the K-5, K-5 II, and K-5 IIs, the Pentax K-3 has a slightly narrower overall sensitivity range of ISO 100 to 51,200 equivalents, because it drops the ISO 80 position. Step sizes of 1/3, 1/2, or 1EV are available. There's also an Auto ISO sensitivity function, whose upper limit can be manually set anywhere up to ISO 51,200 equivalent.

The good news is that the entire range is now available without needing to enable ISO expansion. This suggests that Pentax is happier with performance towards the upper end of the range than it was in the earlier cameras. (With those models, everything above ISO 12,800 was disabled by default.) That's good news if you're a fan of available light photography.

Another piece of good news is that there is no longer an ISO 1,600 cap when shooting in Bulb mode, as there was in earlier cameras. You can now use sensitivities up to ISO 3,200 for bulb exposures, instead.

If you're mourning the missing ISO 80 setting, you can recapture its effect by deliberately overexposing a third stop, and then dialing back the exposure post-capture. That's essentially what the camera was doing before, if it was configured to shoot below its native ISO. You'll lose a little highlight detail -- or latitude for pulling the exposure further -- in the process, but that was already the case with the expanded ISO 80 position on earlier models anyway.

As in past cameras, you can configure the Pentax K-3 to raise sensitivity more or less readily than the default.

Performance. Pentax has increased burst performance of the K-3 beyond the already swift K-5 II and IIs. Those cameras were manufacturer-rated for seven frames per second, and in our lab testing came quite close, with a measurement of 6.7 fps. By contrast, the Pentax K-3 is manufacturer-rated for 8.3 fps, 18% faster than its predecessors. Sadly, our lab testing didn't bear this out, recording around 7.1 fps, just 0.4 fps faster than the previous camera. We should note that Pentax measures at ISO 100, however, while our standard is to measure at ISO 200.

The improved speed isn't achieved solely thanks to the PRIME III image processor, incidentally. The processor is said to have five times greater performance, but it's just part of the puzzle, Pentax has gifted the K-3 with a new control mechanism that regulates mirror, shutter and diaphragm motors independently, with greater speed and accuracy. It's also designed a new mirror damping mechanism to better control mirror shock.

The Pentax K-3 shoots faster than ever before, thanks to a new processor, uprated mirror / shutter / diaphragm control, and a new mirror damping mechanism.

It's not just burst rate that has improved, either. Pentax rates burst depth at around 60 JPEG frames, and we actually measured 75 frames with our hard-to-compress target. That's more than 2.5 times the 28 frames we measured for the K-5 II and IIs. And while raw burst depth hasn't shown a similar increase -- we measured 24 frames, versus the 22 frames we measured with the earlier cameras -- that in itself is actually in improvement. After all, each shot now contains 50% more pixel data thanks to the increase in resolution, and there's the increase in burst speed to take into account, as well. In fact, Pentax says that the DDR3 SDRAM buffer memory capacity in the K-3 is double that of the K-5 II, although it doesn't state the precise amount used.

Another nice change is that there are now two reduced-speed burst shooting rates available, rather than the one offered in every flagship camera since the K-7. Not only that, but they're both more realistic rates, as well. Instead of the not-very-useful 1.6 fps low-speed rate that was introduced with the K-5, we now have a choice of 3.0 or 4.5 fps. That should prove handy for situations where you don't need the full 8.3 fps, but you're still shooting faster than you'd want to by rapidly pressing the shutter button. (Although we'd still like to see the ability to manually dial in your own chosen shutter speed for reduced-rate capture.)

As you'd expect, the lower-speed burst modes have even greater burst depths. At 4.5 frames per second, Pentax claims a depth of 100 JPEG or 32 raw images. Drop the speed to 3.0 fps, and the company predicts a depth of 200 JPEG or 52 raw images. We didn't test these modes, but given that our measurements for burst depth at full resolution actually bettered Pentax's in-house figures, we'd expect these to hold true.

Shake reduction. Also updated for the Pentax K-3 is the company's three-axis Shake Reduction stabilization system, which can correct for vertical and horizontal motion, as well as for rotation around the central axis of the lens.

The system in the K-5 II and IIs could provide a four stop correction to Pentax's own in-house standards. That is to say that shooting at 1/4 second would yield a result similar to that you'd expect when shooting at 1/60th second, in terms of blur from camera shake.

The K-3's system, now has a servo controller dedicated just to shake reduction, and Pentax has also increased the magnetic strength of the sensor shift mechanism. This, it promises, will yield "more stable, effective camera-shake compensation than ever before." While the system is now rated as good for a 3.5 stop correction, that figure is to a new CIPA standard -- and we're told that the K-5 was capable of around a 3-stop correction when measured in the same manner.

On-demand low-pass filtering. As explained in detail by IR publisher Dave Etchells in our "Geek's Guide to On-Demand Low-Pass Filtering" above, the Pentax K-3 is unique among all DSLRs in providing for the subtle blurring required to fight moiré, false color, and jaggies when you want it, and the maximum sharpness and detail when you don't. With every other camera on the market, that decision was either made for you when the camera was still on the drawing board, or it was made when an assembly-line worker at the factory installed -- or didn't install -- an optical low-pass filter in your particular model.

The importance of this system for your photography can't be overstated. It places control back in your hands, letting you decide what's most important for you on any given shot. Personally, we'd recommend shooting with the AA Filter Simulator function enabled most of the time, so that you're not surprised by hard-to-remove moiré in a once-in-a-lifetime shot, and then selectively disabling it if you want the absolute maximum detail for a specific shot.

The Shake Reduction system in the Pentax K-3 is also used to provide a mechanical form of low-pass filtering. The system works as shown in the video above, provided by Pentax.

Because the system reaches its limits at exposures of 1/1,000 second or faster, you'll find that the strength of its effect is diminished beyond this point, regardless of your choice, something to bear in mind when choosing your exposure variables.

One thing in particular strikes us as interesting about the system: Pentax has achieved this with a Shake Reduction mechanism that was already in the camera. Yes, the SR assembly would appear to have been uprated somewhat, and that's likely in part due to the requirements of the AA Filter Simulator function, but it's not used solely for the function. That means it will likely have added little to the bill of materials cost, and to the final retail price of the camera.

And in the process, it means that Pentax now only needs stock one camera on store shelves, to counter two rival models -- one with, and one without the low-pass filter. Half as many SKU codes means significantly less hassle in getting product on the shelf in the first place, and keeping stores stocked.

(Nor is this the only unique feature Pentax is providing with its sensor shift mechanism, as we'll see when we come to features such as horizon correction, composition adjustment, and astral tracking. But let's not get ahead of ourselves.)

Lens mount. It's taken a while, but we've reached the first feature which hasn't changed in the Pentax K-3 -- and that's good news. (Don't worry, there are plenty more new features to come!)

The Pentax K-3's K_AF2 lens mount is a variant of the K-mount that has been used in all Pentax digital SLRs to date, as well as the K-01 mirrorless camera. According to Pentax, the K-mount now has the "largest offering of APS-C optimized lenses in the imaging industry".

In all, there are 32 Pentax K-mount lens models currently on the market, ignoring variants of existing lenses such as the DA-L vs. DA (plastic vs. metal mount) and WR vs. non-WR (weather sealed vs. non-weather sealed) optics. Of these 32, all but four are DA, DA*, or DA Limited-lenses, designed for digital. Three more are D FA models, which are intended for digital SLRs, but with a 35mm full-frame image circle. That leaves 25 APS-C, digital-specific lenses.

And of course, as well as these 32 current optics, you can use older Pentax K-mount glass (some with restrictions), as well as the company's historic 35mm screwmount and 645/67 medium format lenses with an adapter (and again, with restrictions.) You can also mount a wide selection of third-party K-mount lenses from the likes of Sigma, Tamron, and more, and optics from a healthy variety of other mounts with adapters (and limitations).

Dust removal. If you regularly change lenses -- or use consumer-grade glass that sucks air in and blows it back out every time you rack the focus or zoom -- you can expect dust to get inside your camera sooner or later. (Most likely, sooner.)

The Pentax K-3 retains the same DR II dust removal system as its predecessors.

Pentax has retained the same DR II dust removal system used in other recent flagship models for the new K-3. It uses a piezoelectric element that vibrates at higher frequencies than a sensor shift system can, and in our experience systems like these typically do a better job of shaking free dust that's stuck to the sensor's protective cover glass.

To help you decide when a more detailed cleaning is needed, the Pentax K-3 also retains its predecessors' dust alert function, which helps you to locate stubborn dust particles on the sensor for manual cleaning.

Lens correction. Also unchanged is the Pentax K-3's lens correction functionality. This can correct for both lens distortion and lateral chromatic aberration in-camera when using DA and DFA lenses, as well as with some FA Limited lenses.

Metering. And now, for something completely different: The Pentax K-3 sports a brand-new metering sensor. Gone is the 77-segment metering sensor introduced with the K-7 back in 2009. In its place is a much finer-grained 86,000 pixel RGB CCD metering sensor.

That's more than 1,100 pixels for every segment that was on the earlier sensor, and it allows for much more precise metering measurements. And since it's an RGB chip, it can also recognize color information, allowing it to help out with subject identification. (More on that in a moment.)

Branded as the Real-Time Scene Analysis System, the new metering system also has a wider working range of -3 to 20 EV with a 50mm f/1.4 lens at ISO 100. By comparison, the earlier sensor had a range of EV 0 to 22, making it rather less sensitive in low light, although the new chip trades off a bit at the other end for its improved low-light chops.

The Pentax K-3's metering controls are totally different to those of earlier cameras. Gone is the physical metering switch introduced with the K-7, which was fiddly to adjust, but had the advantage that you could confirm your setup without powering the camera on (and, with familiarity, by touch). In its place is a new Metering button which shares double-duty with the Delete button, at top left of the rear panel. If you hold this in and turn either dial, the metering mode is changed, and the new mode shown in the viewfinder, info LCD, and main LCD (if enabled.) And since there's no longer a physical control for metering mode, it's indicated at all times in the info LCD.

Although the new sensor is much finer-grained, the choice of metering modes is unchanged from earlier cameras: Multi-segment, Center-weighted, or Spot. An exposure lock function is available, accessed with the AE-L button that has been relocated to the top right corner of the camera body, above the thumb grip. You can also specify up to +/-5EV of exposure compensation, or bracket 2, 3, or 5 exposures with up to 2EV between exposures. For either compensation or bracketing, you can specify your adjustment in 1/3 or 1/2 EV steps.

Autofocus. Also brand-new is the Pentax K-3's autofocus sensor, which is now a SAFOX 11 chip. This is the first major step forwards since the SAFOX VIII chip that was introduced a decade ago, with Pentax's very first digital SLR, the *ist D.

Every subsequent APS-C SLR from Pentax -- right up to last year's SAFOX X -- has used a variation on the SAFOX VIII layout, albeit with some important improvements in the AF sensor design, optics and algorithms. (And in a few cases on entry-level DSLRs, with the number of points having been reduced.) Never until now have we seen an overhaul like this in Pentax DSLR autofocus, though.

SAFOX 11 provides much better autofocus granularity, thanks to an increase in the number of autofocus points to 27. Of these, the 25 central points in a 5x5 array are all cross-types, sensitive to detail in both the horizontal and vertical axes. Only two points, located in the vertical center at far left and right of the array, are linear points sensitive only on one axis. (Earlier cameras, too, had mostly cross-type points -- they just had a lot fewer of them.)

The Pentax K-3 has a brand-new 27-point autofocus sensor, including 25 cross-type points.

The centermost sensor as well as the points directly above and below it are precision points, capable of focusing with an f/2.8 aperture. That's a feature which was introduced on the K-5 II and IIs, incidentally, although with those cameras, only the centermost point was an f/2.8 precision point. The new autofocus sensor has a working range of -3 to +18EV, unchanged from the previous SAFOX X sensor.

Just as with the metering controls, Pentax has also completely changed the controls relating to autofocus. This has most likely been done because of the added complexity of the new 27-point AF system, and while the new controls will take a little getting used to for K-7, K-5, K-5 II or K-5 IIs shooters, they'll quickly become second nature. (And as with the metering control, the only real downside is that you can't confirm setup without the camera being powered on.)

The Focus Mode switch sits just where it did, on the left side of the camera body behind the lens, near its base. However, it's no longer used to choose between focus mode and servo mode. Instead, it selects solely between manual and automatic focus modes. To change the servo mode, you hold down a new AF Mode button, which sits right above the Focus Mode switch, and turn the front dial. Your choices -- AF-S (single-servo), AF-C (continuous-servo), and automatic selection (AF-A) -- are indicated on the camera's displays, just as the metering modes are.

Alternatively, you can hold the AF Mode button and turn the rear dial. In this case, you'll control the AF point selection, and here you have quite a few more choices, which depend to some extent on the servo mode setting. As well as the default 27-point auto selection, you can opt for Spot, Select, or 9-point modes. Spot is fixed at the center of the frame, but Select and 9-point modes allow you to reposition the center of the focus point cluster anywhere within the focus point array. For single-servo autofocus, Select allows only a single point to be chosen. In continuous-servo mode, it allows you to select a single point, a 3x3 array, a 5x5 array, or the entire AF array. Focus starts from the center point, but will be tracked anywhere within your selected array.

One further control is brand new, located at bottom right of the camera body. The Change AF Point / Card Slot Switch button selects whether the Four-way Controller should be used to adjust the AF point location, or should abide by the markings on its buttons. Each press of this new control emits an audible beep, so you notice that you've changed the controller mode. And since there's no longer a physical control for point selection, it's now indicated in the top deck info LCD.

You might wonder why, exactly, do you need all these new autofocus points? If you're not shooting on a tripod, you can just reframe and focus with one of the existing points, after all. It's with tracking that the extra points are going to pay dividends, though. The more points you have, the easier it is for the camera to accurately track distance as your subject moves across the image frame. And that's where the tie-in with the RGB metering sensor comes in, as well. Since it can now provide color information -- and a whole lot finer detail -- to the camera, it can be used to help track the subject's location, and determine whether or not a given autofocus point is over the subject. In other words, we can expect quite a step forwards in tracking autofocus performance.

Hand-in-hand with this improvement, Pentax has also added a new autofocus hold setting for use in tracking, which will let you control how quickly the camera will react to a radical change in detected subject distance, such as you might get when shooting through a fence, or if somebody walked between camera and subject. You have four options, as shown in the video above: either the change will be near-instant with Hold AF Status set to off, or you can choose one of three durations (Low, Medium or High) after which the change in focus will be made.

Pentax now lets you control how quickly the K-3 will respond to a radical change in subject distance.

As in the earlier cameras, you can also define whether a focus lock or a full shutter button press should be of greater importance to the Pentax K-3. In single-servo mode, you can choose focus priority to have the camera wait to trip the shutter until a focus lock is achieved, or shutter priority to take it as soon as you full press the shutter button. In continuous or AF-A modes, you can opt for focus priority, or frame rate priority (which takes another photo as soon as the shutter has recycled and there is available buffer space to do so).

Of course, you can focus manually as well. Here, there's little new to note, although if you shoot in live view mode, there's a new focus peaking display to help you ascertain the exact point of focus.

Pop-up flash. Although its physical design has changed subtly, with a slightly smaller surface area and a linear Fresnel lens in place of the previous circular Fresnel, the specification of the Pentax K-3's built-in, pop-up flash is unchanged. It still has a mechanical release, and so will not scare the daylights out of you by releasing seemingly at random, as happens on some consumer cameras. It will also release with the camera powered off, though, so you'll want to be careful that nothing could bump the button in your camera bag.

Rated at 13 meters / ISO 100, the K-3's onboard flash offers 28mm coverage plus red-eye removal capability. The K-3 still provides X-sync at 1/180 second, offers -2 to +1EV of flash exposure compensation, and can give both first- and second-curtain flash.

In Wireless mode, the built-in flash can be used as a controller to multiple wireless slave flashes. The built-in flash can be set to contribute to the exposure, or to act only as a controller. The Pentax wireless flash system offers four control channels, so up to four camera/flash setups can be used in the same area without interfering with each other.

External flash. As you'd expect, there's also a standard hot shoe on the top deck, complete with intelligent connections to support Pentax's P-TTL flash metering system. A locking pin is also provided, to ensure your flash doesn't detach from the camera during use.

As well as the hot shoe, the Pentax K-3 also includes a PC sync socket. It's protected by a small, screw-in cap which isn't attached to the camera body, so you'll want to ensure it's snug so as not to lose it.

Still, it's nice to have the terminal at all -- competitors such as the Canon 70D and Nikon D7100 force you to buy a hot shoe to PC terminal adapter, if you want to hook up your studio strobes.

Viewfinder. Pentax has also redesigned the viewfinder used for the Pentax K-3. Like that of earlier models dating back to the K-7, it's pentaprism-based, and has 100% coverage.

New optics mean that it now has slightly higher 0.95x magnification, though, where the earlier design had 0.92x magnification. That might be a very small increase indeed, but it's enough to put Pentax back to the top of the top of the APS-C viewfinder magnification charts, in a two-way tie with the Nikon D7100.

The new viewfinder is also brighter than that of the K-7, K-5, K-5 II, and K-5 IIs, thanks to a new coating on the prism with improved reflectance.

Like those which preceded it, the Pentax K-3's new viewfinder accepts interchangeable focusing screens. The bundled screen is still an MF-60 Frame Matte type.

Although the dioptric adjustment range of -2.5 to +1.5m^-1 is unchanged, the Pentax K-3's adjustment control is new. The earlier cameras had a linear slider control with no detents, directly above the viewfinder eyepiece. The K-3 has a rotary dial tucked in behind the right side of the viewfinder eyecup, and it has around 20 detents. While the fixed detents mean you won't be able to adjust it quite as accurately, the new control is easier to adjust, and no more or less likely to be bumped.

The new design does mean that there's a new viewfinder eyecup, as there's no longer any need for the cutout in its top surface to provide access to the diopter adjustment slider of earlier cameras. It's still removable, and your existing eyecups will still fit,so long as you don't mind the vacant slot at their top.

LCD. The Pentax K-3's rear-panel LCD monitor is also a new design. It has a slightly greater 3.2-inch diagonal, and a 3:2 aspect ratio. Together, those changes translate to around a 9% increase in surface area, and resolution has simultaneously been increased by around 13%. The total dot count is now around 1037k, up from 921k in the earlier flagships. The increase in resolution more than offsets the larger surface area, so perceived resolution is much the same as it was.

The K-3's LCD monitor has a gapless design, as introduced on the K-5 II and IIs, and retains the anti-reflective coating of earlier models. Compared to the air-gapped design used in the K-7 and K-5, it has lower glare and better contrast. It's also slightly brighter, richer, and saturated when compared side-by-side with the K-5. (Unfortunately, we don't have a K-5 II or IIs on hand to compare it to.)

There is certainly one upgrade versus the K-5 II and IIs, though. The Pentax K-3's brightness and color adjustments have been supplemented with a new saturation adjustment, letting you tweak yet another variable to your own tastes.

Info LCD. The monochrome info display on the top deck is similar to that of the earlier cameras, but adds some new information, accounting for a couple of physical control changes to the camera body. There are now indications of both metering mode and autofocus point selection, as well as of the dual flash card slots and the file types used for each.

The info LCD still has a green backlight, which illuminates when you adjust any control. If you don't want to disturb your night vision, the backlight can be disabled.

Exposure modes. In most respects, the Pentax K-3 offers the same selection of exposure modes as did the K-5 II and IIs, as well as their predecessors. As well as Green (fully automatic), Program (with program shift), Shutter priority (Tv), Aperture priority (Av), Manual, and Bulb, there are a couple of Pentax exclusives: Sensitivity priority (Sv), and Shutter-and-Aperture priority (TAv). In these latter two modes, you can either dial in a sensitivity and let the camera select aperture and shutter speed, or dial in the aperture and shutter speed, then let the camera select the sensitivity. There's also a Flash X-Sync mode, which locks the shutter speed at 1/180 second.

The only changes to the selection of exposure modes are that movie capture no longer merits its own position on the Mode dial, and the previous User mode has been replaced with three separate User modes (U1, U2 and U3). That's something of a mixed blessing: It means you can now quickly access those User modes from the Mode dial, but it also means you've lost two user modes, since the K-5, K-5 II and K-5 IIs had five apiece. (If you're coming from the Pentax K-7, though, you'll actually have gained two User modes, since that model only had one.)

You can opt for various program lines when using automatic or semi-automatic exposure. As well as the default program line, you can bias the camera in favor of higher shutter speeds, a shallow or deep depth of field, or towards the MTF sweet spot of the lens.

Drive modes. Drive mode options in the Pentax K-3 include continuous (high, medium, or low), self-timer (two or 12 second), remote control (instant, three second, or continuous), bracketing, mirror lockup, HDR, and multiple exposure. (More on these last two in the creative section below.)

As mentioned previously, burst shooting performance has been improved to a manufacturer-rated 8.3 frames per second (we measured 7.1 fps), with 4.5 fps and 3.0 fps options added in place of the earlier 1.6 fps rate. The bracketing mode allows 2, 3, or 5 shots with up to 2EV between exposures.

Shutter. The Pentax K-3's shutter speed range is unchanged from that of the K-5 II and IIs, but the shutter mechanism itself is updated. It now has a rated lifetime of 200,000 cycles, double the 100,000 cycles of earlier models. (And you can hear that the mechanism is new, too, if you put your ear to the camera -- the noise when the shutter cycles is noticeably different, although it's just as quiet.)

Available shutter speeds range from 1/8,000 to 30 seconds in 1/3 or 1/2 EV steps, plus bulb.

White balance. In most respects, white balance with the Pentax K-3 is similar to preceding models, but one feature is new. There's now a Multi Auto WB mode, which aims to neutralize color casts from multiple different light sources in the same scene. It's an adoption from new parent Ricoh, whose cameras have had the feature for a while now under another name: Multi-P Auto.

As well as Automatic and Manual modes, the Pentax K-3 provides ten white balance presets (Daylight, Shade, Cloudy, Daylight Color Fluorescent, Daylight White Fluorescent, Cool White Fluorescent, Warm White Fluorescent, Tungsten, Flash, and Color Temperature Enhancement). This last option is used to retain and enhance the lighting tone - for example, to enhance a sunset.

White balance can also be measured from a neutral target, or a specific color temperature can be dialed in manually, using either Kelvin or Mired values. Three custom white balance values of each type can be stored in-camera. And finally, you can adjust white balance within a +/- 7-step range on both amber-blue and green-magenta axes.

Creative. To say that the Pentax K-3 has a healthy selection of creative options would be an understatement. We've already briefly mentioned a couple: HDR mode and multiple-exposure shooting.

HDR mode captures multiple images, then microaligns them in camera and blends them to create a single image with greater dynamic range. You have a choice of automatic blending, or one of three effect strengths. These range from fairly natural to a bolder, crunchier feel. (And since the images are microaligned, the mode can be used handheld.) And uniquely, the mode now allows you to output a raw image, although only Pentax's own software recognizes these -- every other app we tried saw them only as a single non-HDR raw. (But you can split the HDR raw into three non-HDR raws using Pentax's software, allowing you to tweak the results in your own HDR app.)

Multiple exposure mode is similar to that in earlier cameras, but with two changes. It still allows you to merge multiple images, and you can still save your result as a raw image. However, there are now three methods of merging images. In addition to the existing additive and average modes, there's now a bright mode which takes the brightest pixel at any given location in the source images, and uses that in the final image. You can also now merge up to 2,000 frames, rather than the previous limit of nine frames.

There's also a time-lapse function, which allows shots at 2-second to 24-hour intervals. You can now capture a lot more shots in an interval series, however. Instead of the 999 shot limit of the K-5, K-5 II, and K-5 IIs, the Pentax K-3 will shoot as many as 2,000 shots in a series.

There is now one more custom image effect in the Pentax K-3, and four new pre-capture digital filter effects have replaced existing ones which have been retired. The new custom image effect is called Radiant, and the new pre-capture digital filters are Shading, Invert Color, Unicolor Bold, and Bold Monochrome. These were all seen previously in the Pentax Q and Q7 mirrorless cameras, and they replace the earlier Soft, Starburst, Fish-eye, and Custom filters from earlier K-series flagships.

Copyright tagging. Like the flagship models which precede it, the Pentax K-3 can optionally embed copyright data into its raw and JPEG image files. You can enter both a photographer and copyright holder name from the camera body, and the headers of images will be tagged with both. It's not a permanent tag, and so you can't rely on it to protect your images from copyright theft, but it does make it so that you can easily identify who shot a particular image in your library.

Dual-axis level gauge. Also unchanged is the Pentax K-3's dual-axis level gauge function. This detects both side-to-side roll, and front-to-back pitch. Roll is displayed in the viewfinder, and on both top / rear LCDs. Pitch can be displayed only on the rear LCD. There's still no way to calibrate the level gauge yourself -- a retun to the service depot is needed if the tilt sensor loses its calibration.

Horizon correction. Pentax's recent flagships go a lot further than most DSLRs, which simply show pitch, though. Like its other flagships, the Pentax K-3 can automatically correct for up to two degrees of roll in either direction if Shake Reduction is disabled, or one degree if it's enabled. If you're driven to distraction by tilted horizons, it's a great feature to have.

Composition correction. Horizon correction takes advantage of Pentax's sensor-shift system, and so to does composition correction. This is handy when you're shooting on a tripod, and want to make very slight adjustments to composition. You can move the sensor left, right, up, or down, and rotate it by up to a couple of degrees, fine-tuning your composition to perfection.

Playback. The Pentax K-3's new LCD monitor has a wider aspect ratio and a slightly higher resolution, and that has translated to some subtle changes in playback mode. For one thing, the number of thumbnail images shown on-screen at any given time has been changed, and now varies from a minimum of six to a maximum of 80. The display magnification is now 16x max., instead of 32x max., and there's a new 100% quick magnification function which helps you check focus at 1:1 resolution without needing to fiddle with the playback zoom controls.

In other respects, though, things are much as before -- and much as you'd expect on an enthusiast camera. You can develop raw images in-camera, compare images side by side, get a warning of bright / dark areas in images, and view both RGB and luminance histograms to confirm you've nailed your exposure.

Just as in record mode, the selection of playback image filters has been changed, with four modes dropped, and four added. The new filters are the same as those in record mode: Shading, Invert Color, Unicolor Bold, and Bold Monochrome. The filters they replace, though, differ. You lose the Custom filter as in record mode, but you also lose the monochrome, color, and HDR filters from earlier cameras.

Movie capture. There are some huge changes in Movie mode, and among them all, the key change for our money comes thanks to the new image processor. There's no more dated, inefficient Motion JPEG compression, with the Pentax K-3 using MPEG-4 AVC / H.264 compression in a .MOV container. (OK, that's not entirely true -- interval movies, which we'll come to in a second, are still shot with Motion JPEG compression. All real-time movies are shot with H.264 compression, though.)

The Pentax K-3 also brings a much better selection of frame rates. As you may remember, the K-5 and K-5 II / IIs were limited to 25 frames per second at Full HD (1080p) resolution, and 30p / 25p at lower resolutions. The Pentax K-3 blows this out of the water, providing either interlaced 60i / 50i or progressive-scan 30p / 25p / 24p at Full HD resolution. At the lower 720p resolution, you'll find the same selection, except that the interlaced frame rates are replaced with progressive scan 60p / 50p rates.

And with the new, more efficient compression, Pentax no longer sees the need to provide for standard-def capture, so it's dropped the VGA resolution of earlier cameras entirely.

The Pentax K-3 also offers more intuitive movie controls. There's no longer a separate Movie mode on the Mode dial, and you don't use the same shutter button for stills and movies. Instead, a quick flick of the rear panel's Still / Movie switch puts the camera in Movie mode, and the new Movie button adjacent to the LCD display starts capture.

There's also a better selection of capture modes for movies. As well as the existing Program and Aperture-priority exposure modes, the Pentax K-3 now supports shooting with Shutter-priority or fully Manual exposure. That's big news if you want the maximum creative control over your movies.

The K-3's built-in microphone is still monaural, but it's been moved to the front panel, which should provide for better audio quality since it faces your subjects. If you want to avoid picking up noise from the camera's autofocus drive (or just want greater control over audio), the Pentax K-3 still provides for an off-camera microphone courtesy of a standard 3.5mm stereo mic port. There's also a new 3.5mm stereo headphone port, which means that you can monitor audio levels before and during capture. The K-3 also provides levels display before and during capture, completely with a peak hold function, and separate display of left / right channels.

Alongside the existing 3.5mm stereo microphone port, the Pentax K-3 sports a brand-new 3.5mm stereo headset port, so you can monitor audio levels during capture.

Another new addition is autofocus during movie capture. It's not the fastest and it only provides single operation, rather than full-time autofocus. Still, it means you don't have to pull focus manually or set your shoot up so as to keep your subject within depth of field. Pros and enthusiasts will still want to do so, however, which is easier to do thanks to fully manual exposure control.

There's still a 25-minute clip length limit in the Pentax K-3, and so if you need to have longer continuous shooting, you'll need to look for another solution. Another new feature, though, is the interval movie mode which was first introduced with the Pentax Q, and made its K-mount debut on the Pentax K-30. This has been reworked in the Pentax K-3, and now shoots at up to 4K resolution (3,840 x 2,160 pixels). If your clips are lengthy, you can expect some seriously colossal file sizes -- around 3GB per minute -- at this resolution, thanks to the Motion JPEG / AVI compression but the ability to shoot ultra high-def time-lapse video is nevertheless pretty cool.

The Pentax K-3 is sealed against dust and water, and freezeproof to 14°F / -10°C.

Weather-sealing / cold-proofing. The Pentax K-3's body is still comprehensively dustproof and weatherproof, thanks to seals at all controls and body seams. The number of seals has been increased from 77 to 92, but we wouldn't necessarily take this to indicate a greater degree of sealing -- there are simply more controls that need sealing on the newer version. Pentax's flagship DSLRs have a reputation as among the best-sealed in the business, regardless. And the K-3 is also still freezeproof to 14°F / -10°C, and works reliably in temperatures up to 104°F / 40°C.

And it's not just the body that's weatherproof, either. Regardless of whether you're shopping for consumer or enthusiast-grade gear, weather-sealed options are now available to you. The optional portrait / battery grip is sealed to the same standard as the camera body. Likewise all DA* lenses, and several affordable WR lenses covering everything from 18mm to 200mm have been weather-sealed for some years.

And now, a just announced, weather-sealed variant of the 55-300mm lens takes consumer-grade weather-sealed coverage out to everything from 18-300mm, with just two affordable weather-sealed zooms. Add in Pentax's recently-announced weather-resistant strobes, its weather-sealed GPS receiver, and even a weather-sealed infrared remote, and there isn't a link in the chain that can't be used in dust and rain.

If you plan to shoot in inclement conditions, rest assured: this is truly part of a weather-sealed system.

Connectivity. Another important change in the Pentax K-3 is to be found in the connectivity department: a USB 3.0 Micro B connector, in place of the previous combined USB 2.0 PC / AV connector.

Otherwise known as SuperSpeed USB, USB 3.0 is theoretically 10x faster than USB 2.0 (aka Hi-Speed USB) -- and it's backwards compatible, so if it's not yet supported by your PC or Mac, you can still get USB 2.0 rates.

Alongside the debut of USB 3.0 connectivity, support for standard-definition video output has been dropped. Instead, the Pentax K-3 now offers only a high-definition Type-D Micro HDMI output. We're not yet sure if it supports uncompressed live video over its HDMI port.

We've already mentioned much of the K-3's remaining connectivity, which includes 3.5mm stereo mic and headset jacks, an intelligent hot shoe, PC sync terminal, front and rear infrared receivers, and a connector for an optionally-available portrait / battery grip. There's also an 8.3V DC input, which is unchanged from that in the Pentax K-5 and K-5 II / IIs, using the same K-AC132 AC adapter kit.

Power. The Pentax K-3 retains the same D-LI90 battery as its predecessors, but unfortunately, there's been a significant 24% reduction in battery life. The K-3 is now capable of 560 shots on a charge to CIPA standards, down from 740 shots on a charge with the K-7, K-5, or K5 II / IIs. With no flash usage, you'll get 720 shots on a charge, down from 980 shots in the earlier cameras. Playback time falls from 440 minutes to 370, a 16% reduction.

Battery grip. Thankfully, you can still supplement battery life by using the optional portrait grip. (And with the shorter battery life, we'd imagine it will be more popular than ever.)

Unfortunately, you'll need a new grip: the Pentax D-BG5, replacing the D-BG4 grip which dates back to the K-7. Much like that grip, you can add second D-LI90 for double the battery life (1120 shots on a charge to CIPA standards), or alternatively you can supplement the in-body battery with six standard AA cells. (Battery life here would depend on the AA battery type.)

Either grip battery option is catered for with removable battery trays, and if you're shooting with the D-LI90 battery tray, it also includes space to store a spare Secure Digital card.

The Pentax K-3 uses a new battery grip, and isn't compatible with the grip sold for earlier flagships.

Storage. Speaking of storage, the Pentax K-3 still writes its images in JPEG or 14-bit PEF/DNG raw formats. (The resurrection of the .PEF raw format is good news for anybody who bemoaned the inclusion only of DNG raw on the Pentax K-30, K-50, and K-500.)

A very significant change from the K-3's predecessors is the presence of dual card slots. That catches Pentax back up with rival Nikon, which has offered dual card slots in both the D7000 and D7100. At Canon, you'll have to step up to the full-frame EOS 5D Mark III if you want dual card slots.

The Pentax K-3 allows you to write to its dual card slots in several different ways. You can either write to the cards sequentially, first filling one and then the other, or write to both slots simultaneously for a backup, or write raw images to one slot, and JPEG images to the other slot.

The Pentax K-3 is the company's second camera to include dual flash card slots, after the medium-format 645D. It's also the first Pentax model to support high-speed UHS-I cards.

The K-3 supports both the higher-capacity SDHC and SDXC cards, and the higher-speed UHS-I cards. With the latter, it will not only handle SDR50 / DDR50 cards with a bus speed of 50MB/second, but also SDR104 cards with a bus speed of 104MB/second.

It also supports two differing wireless flash card formats: either the well-known Eye-Fi cards, or the lesser-known Trek Flucards.

Remote control. The latter provide not only for file transfer, but also for remote control. (At least, if you're using a Pentax-branded Flucard.) That means another hole in Pentax's offering has been plugged. Ever since the Pentax K-7, we've bemoaned the lack of an official remote capture solution, and now it's available.

First-party remote capture functionality finally returns to a Pentax APS-C flagship camera, courtesy of optionally-available, Wi-Fi capable Flucards and an Android / iOS app.

When shooting with a Flucard, you can receive a remote live view feed, select the autofocus point remotely, and trip the shutter remotely. You can also adjust other settings such as ISO sensitivity, aperture, shutter speed, and exposure compensation. And you can transfer reduced-size or full-size images -- but not raw files -- via standard Wi-Fi to your PC or smart device. All devices control the camera via a web browser, with no app needed.

We'd still like to see an official tethered shooting solution -- if for no other reason than that we want to see apps like Adobe's Lightroom and Phase One's Capture One supporting tethered shooting with the Pentax K-3 -- but the presence of a wireless solution is still excellent news.

Software. The K-3 digital SLR ships with an upgraded version of Pentax's Digital Camera Utility 5 software. It's still Silkypix-based, just like the previous version.

Accessories. Available accessories include the Pentax D-BG5 portrait / battery grip, which is dust / weather sealed, accepts a second D-LI90 battery pack or six AA cells, and provides duplicate shutter-release, AE-lock, AF, ISO, exposure-compensation and green buttons, as well as a preview lever and dual electronic dials. Pentax also offers an own-branded O-FC1 16GB Flucard Wi-Fi SD card, and a 50cm long, 4cm wide O-ST1401 camera strap in red or black.