Pentax K-r Review

 
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Pentax Kr Video Recording

The Pentax K-r is the company's fourth DSLR to feature the ability to capture video clips, a capability first added in the prosumer K-7 model. Much like the live view capability that preceded it, video capture has rapidly become a must-have feature in the DSLR market. The K-r's video mode shares much in common with that of the recent K-5 flagship, but with a few features removed to reduce cost and create differentiation between models.

Pentax K-r Video: Image Size, Frame Rate, and Encoding

The Pentax Kr's CMOS image sensor records high definition video at a maximum resolution of 1,280 x 720 pixels--otherwise known as 720p--with a 16:9 aspect ratio. In addition, there is a lower resolution, standard definition mode that crops and downsamples the video stream to produce 640 x 480 (VGA or 480p) movies with a 4:3 aspect ratio. Both resolutions provide a fixed recording rate of 25 frames per second. By contrast, the K-x offered a fixed 24 fps rate, and the K-5 provides 25 fps at all resolutions, plus an optional 30 fps at 720p or below.

720p video. The Pentax K-r offers two resolution levels for video recording, topping out at 1,280 x 720 pixels, rather than the higher-res 1,920 x 1,080 (1080p Full HD) mode offered in the flagship K-5. Like the earlier K-x model, both resolutions match existing standards -- 720p and VGA / 480p.

Like its predecessor, the Pentax Kr records its movies as Motion JPEG-compressed .AVI files, rather than the AVCHD or H.264 formats favored by most manufacturers these days. The AVCHD format used by many of the K-r's rivals is a subset of the broader H.264 video compression spec, which places fairly heavy constraints on the recorded bitrate, hence allowing smaller file sizes. Unfortunately, these constraints also conspire to cause a severe loss of image quality in AVCHD video when a lot of the image changes from one frame to the next, as is the case when panning or in closely-cropped video of a rapidly-moving subject. Some cameras with sufficient processing power instead use H.264 encoding at higher bitrates to avoid some of the limitations of AVCHD, but as well as increasing file sizes, this comes with the requirement of greater processing power to encode and decode. Compared to these formats, Motion JPEG is much less processor-intensive than H.264, and avoids AVCHD's compression-related quality loss during panning. The downside, though, is that the Pentax K-r yields very large file sizes: just one minute of 720p video can very easily produce file sizes on the order of 250MB or more, depending on subject matter.

Recording is only part of the story, of course: editing and playback are equally important aspects to be considered. When it comes to editing, the Pentax Kr's AVI format is much easier to deal with than H.264-encoded video (including AVCHD), at least currently. The more sophisticated encoding used in the H.264 standard requires quite a bit of processor power to pull it apart and put it back together again, so frame-accurate editing of H.264 requires a fast processor and capable editing program. When it comes to playback, it's perhaps a bit of a toss-up between the two main formats: AVI plays back much better on computers with relatively modest processors, while AVCHD files can be read directly by some television sets.

Here's a list showing what to expect for file sizes with the Pentax K-r's video recording:

Pentax K-r Video Options
Motion JPEG Format (.AVI files)
Menu Designation
Resolution and
Frame Rate
Quality Level
File Size

HD

1,280 x 720
25 fps
(720p HD)

Best (***)

150 - 260 MB/minute

Better (**)

150 - 180 MB/minute

Good (*)

110 - 130 MB/minute

VGA

640 x 480
25 fps
(VGA / 480p SD)

Best (***)

50 - 70 MB/minute

Better (**)

45 - 50 MB/minute

Good (*)

20 - 35 MB/minute

(Measurements were made with a hard-to-compress digital noise image, and a blank white screen, to show the extremes in terms of high and low bitrate, respectively.)

Compared to the K-x, our tests of the K-r's frame size and compression levels showed slightly higher compression levels across the board, with a fairly even progression in file sizes as compression levels were decreased, although the file sizes were significantly greater (and more dependent on subject matter) in the highest quality 720p mode than for other compression levels and resolutions.

The file-size results correspond to what we found in the K-r's video files: The best image quality is definitely achieved in its 720p Best-quality mode, but you'll need to pay the piper in terms of flash card space. Stepping up from Better to Best quality adds almost 50% to file sizes, all other settings remaining the same, and the K-r will devour 2GB of card space in as little as seven or eight minutes.

Here are some examples of video from the Pentax K-r, showing typical results under daylight and night conditions.

Pentax K-r Video Samples
shot with smc PENTAX DA 17-70mm F4 AL (IF) SDM lens
Daytime Videos

1,280 x 720, 25fps, Best (***) Quality
View on Vimeo | Download Original
(14.0 seconds, 60.2 MB)
1,280 x 720, 25fps, Better (**) Quality
View on Vimeo | Download Original
(13.0 seconds, 39.7 MB)
1,280 x 720, 25fps, Good (*) Quality
View on Vimeo | Download Original
(12.0 seconds, 26.1 MB)
640 x 480, 25 fps, Best (***) Quality
View on Vimeo | Download Original
(13.0 seconds, 14.5 MB)
640 x 480, 25 fps, Better (**) Quality
View on Vimeo | Download Original
(15.0 seconds, 12.2 MB)
640 x 480, 25 fps, Good (*) Quality
View on Vimeo | Download Original
(12.0 seconds, 7.1 MB)
Night Videos
Note: The popping / clicking noise on the Vimeo versions of the night clips below is not present in the original videos. We're currently in communication with Vimeo to resolve this issue. Apologies for the inconvenience!
1,280 x 720, 25fps, Best (***) Quality
View on Vimeo | Download Original
(14.0 seconds, 60.0 MB)
640 x 480, 25fps, Best (***) Quality
View on Vimeo | Download Original
(17.0 seconds, 19.1 MB)



Pentax K-r Video-Mode Focusing

When we first saw a prototype of the prosumer K-7 model prior to its announcement, were excited to see that it supported contrast-detect autofocus during movie recording, something that would've been unique among prosumer DSLRs at the time. Unfortunately, this feature never made it into Pentax's production-level cameras, and the K-r retains the status quo in this regard. Digital SLR video capture has come a long way since the launch of the K-7, and many competing cameras do now offer this feature. Notably, Canon introduced the ability to perform single AF operations with its Rebel T2i in February 2010, while Nikon followed suit with full-time AF in the D3100 from August 2010, and both companies have since introduced the same in-movie AF options in their prosumer models as well. Hence, where the omission of in-video AF was merely a shame in Pentax's earlier cameras, it now stands out as an area where the K-r lags its main rivals.

While the absence of in-video AF wouldn't likely be of any importance to professionals, the bulk of the K-r's target market is made up of enthusiastic amateurs, and for many, the requirement to focus manually is a step too far. It takes significant practice and no small dose of talent to pull focus manually, and doubly so if you're also having to pay attention to image framing, etc. Even bearing in mind that the K-7 prototype's contrast-detect AF cycle was rather slow, visible in the video, and quite audible via the built-in microphone with most lenses, we think that many enthusiast videographers would welcome its presence in Pentax's DSLR lineup all the same. Audio issues notwithstanding, for those who can't master the arts of pulling focus manually, brief moments of contrast-detect "hunting" would likely still prove more acceptable than blurry video -- or no video at all.

As it is, focusing in movie mode with the Pentax K-r is much the same as used to be the case with most other video-capable DSLRs last year: You can trigger a contrast-detect AF cycle prior to the beginning of a recording by hitting the AF button on the camera's rear panel, but there's no autofocus during recording. You can manually focus the lens during a recording, though, and the true manual operation of AF on Pentax's lenses means you can do this more or less silently, simply by being careful about turning the focus ring. (Some cameras we've tested, such as the Olympus E-P1, use "fly by wire" focusing, whereby the focus ring only instructs the camera to move the lens elements rather than moving them directly via a mechanical coupling. This means that small clicks can be heard on the audio track every time the camera changes the focus setting, regardless of how slowly you turn the focus ring. With true manual operation of its lenses, the Pentax K-r doesn't have this problem.)

As is the case in Live View mode, pressing the Info button on the camera's rear panel lets you zoom in up to 6x when AF is enabled, or as far as 10x when set to manual focus mode, to assist with precise focusing, but note that this is only possible before recording has started: Once the camera has begun recording, only the normal 1:1 view is available. A new function of the K-r's pre-capture contrast detection autofocus is that during the AF operation, the live view feed automatically zooms in on the focus point -- whether it is manually selected, or set using face detection -- making it much easier to see if the lock was accurate. The zoom isn't performed instantly, but rather the view gradually zooms in to help reinforce where within the frame the camera is focusing. This function is something of a mixed blessing, however, in that it can't be disabled, and operates even when in AF-C mode, where you'd expect to be shooting a moving subject. (It does return to a normal view shortly after the initial focus lock, so you do at least see the full image view in between AF operations.) The zoomed view can make it very tricky to continue to follow your subject and keep them inside the image frame while focusing, though, and we'd really like to see the option to disable this otherwise useful feature -- at the very least when Continuous AF is disabled, and preferably at any time of the photographer's choosing.

As we've noted in other SLR reviews, the good news with focusing for video is that you can get surprisingly good depth of field in video mode by stopping the lens down, thanks to the relatively low resolution of the video image. With a pixel resolution of only 0.9 megapixels in the Pentax K-r's 720p mode, and just 0.3 megapixels in VGA mode, images that would be unacceptably blurred as 12 megapixel still shots look perfectly fine as video frames. This not only provides greater depth of field at any given aperture, but is also more forgiving of diffraction limiting at very small lens apertures. Diffraction at small apertures means you'd usually want to avoid f/16 or f/22 for still images, but again, the results generally look perfectly fine at video resolutions. Bottom line, with the K-r's lens set to f/16 or f/22 (assuming you're shooting under fairly bright conditions), you'll be surprised by how little focus adjustment is needed during a typical video recording.

Pentax K-r Video Exposure Control


Pentax K-r Aperture Control / Depth-of-Field
shot with smc PENTAX DA 17-70mm F4 AL (IF) SDM lens
Aperture-priority, f/4.0

1,280 x 720, 30fps, Good (*) Quality
View on Vimeo | Download Original
(5.0 seconds, 10.9 MB)
Aperture-priority, f/22.0

1,280 x 720, 30fps, Good (*) Quality
View on Vimeo | Download Original
(4.0 seconds, 8.7 MB)

The level of exposure control available when shooting video with current SLRs varies widely. Many cameras -- especially those aimed at consumer use -- still opt to keep things simple with fully automatic exposure control. Manual exposure control is also now a reasonably common option, though, especially in prosumer and professional models. Like its predecessor, the Pentax K-r offers somewhere in between these extremes, giving you a choice of either automatic or aperture-priority exposure modes. In Auto aperture mode, the camera adjusts the aperture as needed, but just like the K-x, doesn't report the current value on the LCD screen. (We'd still like to see Pentax change this behavior to allow aperture display regardless of exposure mode, at the videographer's option.) In aperture priority mode -- referred to in the menu system as Fixed Movie Aperture Control -- the current aperture is displayed in the lower left corner of the LCD screen, and can be changed by rotating the rear command dial. You can't adjust it during recording, but whatever value you set before you begin your clip is the one the camera will use. This is a great feature that gives a fair degree of creative control over the look of videos, although it doesn't go as far as some cameras in allowing direct control over shutter speed or aperture.

In common with most other video-capable SLRs, the Pentax K-r offers the full range of white balance settings in movie mode, including four different options for fluorescent lighting, plus Manual and the unusual Color Temperature Enhancement mode. You can also select any of the K-r's Custom Image modes, including Bright, Natural, Portrait, Landscape, Vibrant, Muted, Bleach Bypass, Reversal Film, and Monochrome. As with still-image shooting, settings for saturation, hue, high/low key adjustment and contrast can be adjusted independently for each mode. A sharpness setting is available as well, which affects the sharpness of the video images to a very noticeable degree. (Note that turning the sharpness up too high will make the JPEG compression artifacts much more evident, though.) Unlike its predecessor, the K-r now allows a subset of its digital filter modes -- and one filter specific to the Movie mode -- to be used during video capture. Modes available for both stills and movies include the Toy Camera, Retro, High Contrast, and Extract Color, with each offering varying degrees of control over the look of the effect. The still-image Soft, Starburst, Fish-eye, and Custom filters are not available in Movie mode, but you gain a Color filter mode that allows a red, magenta, blue, cyan, green, yellow filter effect at either light, standard, or dark intensity levels. The K-r's Cross Processing function, which is also available for stills, can be used in Movie mode as well, and its effect -- which emulates a technique from the days of film photography -- can also be combined with the digital filters. If Cross Processing is active, both white balance and custom image mode must be controlled automatically, however.

Two movie-mode exposure parameters that the Pentax K-r unfortunately doesn't let you control are its shutter speed and ISO sensitivity. The shutter speed appears to be tied to the frame rate: regardless of the light level involved, rapid motion is always blurred to about the level you'd expect with a 1/25th second exposure time, with the ISO sensitivity being used to maintain the metered exposure level. You can, however, attempt to bias the camera's exposure towards your desired result with judicious use of the exposure compensation, auto-exposure lock, and metering mode controls. Exposure compensation and lock are applicable not only before, but also during video capture, albeit with the possibility that their use may result in objectionable camera handling noise on the audio track. Since the metering mode is adjusted through the menu, this can only be adjusted before capture starts.

Pentax Kr Video: Image Stabilization

The Pentax K-r's body-based image stabilization can be used when recording movies. Not only does this make any lens you're recording with into an IS model, but we found that the image stabilization worked exceptionally well when recording videos. We've recorded videos with other SLRs using IS lenses, but the level of stabilization available in Pentax's flagship Kr (and its predecessor) seemed better than we're average. Because the Pentax K-r's Shake Reduction system provides such a high degree of stabilization, there's a bit of a "floating" feeling when recording videos with IS enabled: As you move and pan the camera, the video image tends to lag a little behind your motions, "catching up" when you come to a rest. A related IS effect is that the subject can drift up or down or from side to side slightly during recording. This can be slightly disconcerting, but the upside is that your videos will be much more stable than otherwise, even holding the camera at arm's length, or when shooting with a long telephoto lens.

Pentax K-r Video: Audio recording

Like the vast majority of SLRs with video recording capability, the Pentax Kr sports an internal microphone that can record an audio track. Internal mics can be somewhat problematic, in that they're prone to picking up noise produced by moving your hands on the camera or actuating any controls while recording. In the case of the Pentax K-r, the issue can be exacerbated if you choose to use the body-based image stabilization system during movie recording, depending on the degree to which the system is operating. You can hear the IS in the audio track if the camera is jostled a good bit during recording, but not when it's being held relatively steadily: The light clacking sound audible in the face of significant camera movement seems to be the result of the sensor unit bumping up against its stops. If the camera is held even reasonably carefully, you're unlikely to hear any IS-related noise at all, even in a quiet office environment. In normal usage, you thus shouldn't face any problems using the IS system during video capture, unless you're panning quite a bit, or if unstable footing results in a lot of camera movement.

Like that of the K-x before it, we found that the Pentax K-r's built-in mic does a good job of picking up ambient sound, with good sound quality and sensitivity. At the same time, it seemed to be less sensitive to sounds picked up from focus adjustment or hand movement on the body than some other cameras we've tested. As with that of its predecessor, the built-in mic in the K-x is monaural, rather than the stereo mics that are becoming more common these days. It's also not directional, so it will pick up noise from behind or alongside the camera body, not just from in front, but for many purposes where a degree of ambient noise is desirable, that can be a good thing.

Unfortunately, the K-r does lack a couple of features that pros in particular would find desirable. Unlike some of its competitors, Pentax hasn't gifted the K-r with an external microphone jack, and nor does it offer any manual control over audio recording levels. Instead, the camera will determine these automatically, and may adjust them on the fly, resulting in the levels ramping up and down in response to sudden changes in ambient noise levels. For amateur use, this might well be desirable, helping reduce complexity and ensuring that at least the majority of the audio is recorded at roughly the right level. For professional use, though, the lack of any way to adjust the recording levels manually, or to lock them at a particular level, will likely mean that pro videographers will want to rely on an external device for audio capture, simply replacing the camera's own audio in post-processing. This is easy enough to do, and a variety of relatively affordable, compact, high quality external audio recorders from the likes of Zoom make this possible even for enthusiastic amateurs, but it's nonetheless an extra step in the process which could likely be avoided courtesy of a firmware update.

Pentax K-r Movie Recording User Interface

The Pentax K-r's movie mode is still accessed via a separate position on the camera's mode dial, rather than being initiated from within still-picture Live View mode, and just like in the K-x, there's still no separate control button to start/stop movie recording. Instead, pressing the shutter button begins recording, and pressing it again stops it. Many DSLRs these days have a dedicated button to start/stop movie recording, and while newcomers will likely find the K-r's use of the shutter button more intuitive, it draws a very clear dividing line between the camera's still imaging and movie capture functionality. This takes away somewhat from the ability to quickly grab spontaneous, unanticipated video clips, as you have to pay attention to changing the camera's operating mode before you can switch from still to video capture, or vice versa.

Our feelings about having a separate mode for video capture do depend somewhat on the rest of the camera's user interface. On some cameras, combining video capture with normal still-capture mode would increase menu complexity too much, but that wouldn't be an issue with the K-r, given its menu layout. Providing video direct from Live View mode would require the addition of one more button to the camera body with which to control video recording, though, and the K-r's tight control layout leaves little or no room for that.

Setting adjustments in movie mode are made via screen 3 of the Record Menu, where the Movie option leads to a whole sub-menu. We found this a little awkward when making frequent adjustments to video settings, as the extra level of menu selection meant more button-pressing to make the changes than would have been required if they'd been available from the main shooting screen via a "quick menu," as some cameras have. (It also meant unnecessary mirror flipping, as the Live View mode is terminated whenever you enter the menu system.) That said, the commonly accessed options for white balance and exposure compensation were easily accessible via external controls, and when you need to enter the menu, the K-r can at least be configured to remember which menu tab was most recently accessed, saving a few button presses over the earlier K-x model.

The Pentax K-r's Record Menu options for video recording are:


Pentax K-r Record Mode Menu Movie Options
Top-Level
Selection
Second-Level
Notes
Recorded Pixels
- HD (1,280 x 720, 25 fps)
- VGA (640 x 480, 25 fps)
Unchanged from the K-x, though framerate is up from 24 fps.
Quality Level
- *** (Best)
- ** (Better)
- * (Good)
Although three quality levels are available, we found the lowest 'Good' setting introduced too many artifacts across the board.
Sound
- On
- Off
Audio capture with internal or external microphones can be disabled altogether, if desired.
Cross Processing
- Off
- Random
- Preset 1
- Preset 2
- Preset 3
- My1 (Favorite 1)
- My2 (Favorite 2)
- My3 (Favorite 3)
New to video capture since the K-x, this functions identically to its still-image equivalent, and allows color and contrast effects similar to those achieved by cross-processing traditional film. If enabled, you won't be able to control white balance or custom image modes, however.
Digital Filter
- Toy Camera
- Retro
- High Contrast
- Extract Color
- Color
Also new since the K-x, the K-r now allows use of several of its digital filter functions during movie capture. Note that the still image Soft, Starburst, Fish-eye, and Custom filters are not available in Movie mode. The Color filter is an additional option not available in still image mode, and allows either a red, magenta, blue, cyan, green, yellow filter effect at either light, standard, or dark intensity levels.
Movie Aperture Control
- Auto
- Fixed
"Fixed" lets you set aperture via the rear-panel control dial before -- but not during -- video capture.
Shake Reduction
- On
- Off
Shake reduction can be disabled if you're shooting on a tripod, or if the level of shake would be likely to cause too much objectionable noise in your audio track. Note that if you're using the Composition Adjust feature, shake reduction is disabled regardless of this setting.



Rolling Shutter Artifacts

Pentax K-r: Rolling Shutter Artifacts
shot with smc PENTAX DA 17-70mm F4 AL (IF) SDM lens

1,280 x 720, 25fps, Good (*) Quality
View on Vimeo | Download Original
(6.0 seconds, 13.0 MB)

640 x 480, 25fps, Good (*) Quality
View on Vimeo | Download Original
(5.0 seconds, 3.0 MB)

Essentially every video capable DSLR currently on the market exhibits motion-related distortions called rolling shutter artifacts. These are caused because the image data is captured and then read off the chip sequentially by rows, rather being captured all at once. In the case of the Pentax K-r, with its fixed frame rate, this means that image data for the last row of a given frame is captured and read out anywhere up to 1/25th second after the data for the top row was captured. The effect on moving objects is similar to that of a focal plane shutter in an SLR, but more pronounced, because the video frame is read out much more slowly than the slit of a focal plane shutter moves across the sensor.

For a camera that scans video frames vertically (as all do that we're aware of), rolling shutter artifacts will be most noticeable for subjects that are moving rapidly side to side, or when the camera itself is being panned horizontally. Verticals in the scene will appear tilted to the right or left, depending on the direction of camera motion. As an example, consider the case of a camera being panned from left to right, with a flagpole or other vertical object in the middle of the scene when recording for a particular frame begins: If the top of the object was centered horizontally when the first line of the video frame is acquired, by the time the last line of the frame has been captured, the bottom of the object will have shifted to somewhere left of center: As a result, the vertical object would appear to be leaning to the right.

Subjectively, the visual impact of rolling shutter artifacts on the Pentax K-r seemed less significant than those of the earlier K-x model. An upside for the K-r relative to rolling shutter artifacts is its excellent IS system. While you can avoid the worst effects of a rolling shutter by panning slowly, even minor jiggling of the camera due to hand-holding can produce a jelly-like appearance in the video output from some models. The K-r's IS system stabilized the video well enough that we experienced no such effects when the camera wasn't being panned. If our shooting required both stationary shots and rapid panning in the same segment, though, we had to shoot with the IS system disabled to avoid clacking noise in the audio track from the internal mic. With an external mic, this was much less of an issue.


Computer Requirements for Viewing HD Video

A typical computer these days has little trouble dealing with still images, but high-definition video can be another matter. Depending on the file format involved, it can take a pretty beefy computer to handle HD-resolution video playback without stuttering or dropping frames. The Motion JPEG image compression used by the Pentax K-r is one of the less compute-intensive formats, and its standard high-def 720p mode has significantly lower resolution than the Full HD modes on some recent cameras, though. As long as it's a relatively recent and reasonably powerful model, you should have no problem playing video files from the K-r on your computer. We don't have a specific benchmark for this, but if your computer is less than 3 years or so old, it should have no problem with the K-r's video streams. (By contrast, to play AVCHD or other keyframe-encoded video formats at full 1,920 x 1,080 resolution can demand a very powerful CPU and video card, to keep up.)

That said, the Pentax K-r's video codec doesn't appear to be particularly efficient, as it produces very large file sizes at its highest quality setting, even though the compression level seems a little higher than that of the K-x. So, while you might be able to play its videos on an older computer, you'll almost certainly need to increase your hard drive capacity. With video files occupying up to 260 MB/minute, it's a good thing that terabyte hard drives are so cheap these days. (At that pace, a terabyte hard drive could hold about 64 hours of video footage. That's a lot of footage if you primarily use the K-r for casual "video snapshots," but if you're a serious video user, it can go by very quickly.)

 

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