Pentax K-S2 Review
Let's start by taking a look at the Pentax K-S2's video specifications:
- Full HD 1080 (30/25/24p) and HD 720 (60/50p) resolution
- Automatic (P), manual (M), or semi-automatic (TAv, Av) exposure
- On-demand autofocus
- Built-in stereo microphone
- External mic input
- Sound volume adjustment
- Custom image & digital filters
- Digital stabilization
Compared to older entry-level and mid-range Pentax DSLRs, the key improvement in the K-S2 is the addition of an external microphone port. But beyond that, the interface for accessing different movie modes has been overhauled in a brilliant way. The on/off switch has a dedicated setting for movie mode, and the mode dial is now also used to control the movie exposure mode. While the on/off switch design was inherited from the Pentax K-S1, the role of the mode dial in movie mode is new to the K-S2. Since only P, Av, TAv, and M are available for shooting videos, other mode dial settings simply activate P mode.
Thanks to this interface, the K-S2 makes it is easier than ever to access movie mode and to quickly switch between the different exposure modes. The interface is both intuitive and user-friendly.
P mode is a fully-automated movie mode in which the camera sets all parameters automatically, including the ISO. In fact, the ISO is only manually controllable in M mode, which is somewhat restrictive but does keep redundancy to a minimum. The only user-accessible parameter in P mode is exposure compensation.
Av mode lets the user set the aperture while the camera worries about the shutter speed and ISO.
TAv mode lets the user set both the shutter speed and aperture while the camera sets the ISO. This mode does not offer real-time exposure preview and the shutter speed and aperture are not limited by the ISO range, so it is possible to under-expose or over-expose without knowing until video recording starts.
And finally, M mode is an all-manual mode with a real-time exposure preview. The shutter speed, ISO, and aperture can be controlled. The maximum ISO for video mode is 3200.
Across P, Av, and TAv, the exposure settings chosen by the camera are not shown. It is thus impossible to see the ISO being used except in M mode.
Resolution and Framerates
The K-S2 supports 24p, 25p, and 30p recording at Full HD resolution (1920x1080), and 50p and 60p recording at HD resolution (1280x720). We do not know why the slower framerates are unavailable at 720p.
The control panel provides access to a number of settings that affect video image quality and the live view picture. These settings are also duplicated in the video tab of the main menu.
The same custom image presets and digital filters that affect stills can also be applied to videos. For example, thanks to these features it's possible to take a high-key black and white video without having to do any external editing. You can also enable shadow/highlight corrections, and choose between matrix, center-weighted, and spot metering. Finally, you can control the microphone volume and choose whether or not to enable stabilization.
The remaining settings apply to what is shown in live view prior to recording— for example, focus peaking stops as soon as recording starts.
Prior to recording, the same focusing modes are available as for stills. Once recording starts, only a very slow on-demand AF option is available. It can be engaged using the AF button the back of the camera.
The on-demand AF is too slow to lock on to moving subjects, but it is suitable for panning between subjects at different distances.
Angle of View
In video mode a slight crop is applied to maintain a 16:9 aspect ratio, as shown below.
Video mode crop
Due to compression, the K-S2's videos are noticeably less detailed than stills. The dynamic range and color accuracy is also limited. The crop below illustrates the difference between a low-resolution still and a video frame extraction.
The K-S2 saves its video files as .MOV's using the H.264 codec— a very common format that's compatible with most video editing programs. There is no raw video output.
Below is a sample video clip shot at Full HD at 30FPS (1080/30p) with SR enabled.
The digital shake reduction exaggerates the infamous jello effect and is thus not as desirable as sensor-shift or lens-based stabilization. It works well for keeping the picture steady while the camera is held mostly still, but as soon as you start panning or introducing more pronounced movement/vibrations, things don't look too good.
As for sound quality, the on-board stereo microphone is of course an improvement over the mono mics used in previous bodies, but we recommend using an external microphone for even better audio quality. The camera does not do a good job of suppressing background / wind noise on its own.
The K-S2'S HDMI output streams what is shown on the LCD. The resolution is roughly VGA quality.
In playback mode, the K-S2 allows you to split movie segments or extract a segment. Cuts can be made at half-second intervals.
The K-S2 is a stills-oriented camera, and thus isn't cutting-edge in terms of video specifications or video image quality. Other cameras in its class made by other manufacturers have more framerate options, better video quality, and continuous autofocus. Still, it gets the job done for family videos and has all the basic tools (manual exposure, external audio) needed for more advanced projects as well. The new interface for accessing video mode and the different exposure settings is a welcome time-saving enhancement. We're also happy with the articulating LCD.
The biggest area needing improvement is certainly the stabilization, as any entry-level DSLR with a stabilized lens would do a better job than the K-S2's digital SR. While older Pentax models (K-5, K-7) did have sensor-shift video stabilization, this feature has since been removed and was never re-introduced in newer models.
Finally, it would have been nice if the K-S2 could display the shutter speed/aperture/ISO that it chooses in P mode and the semi-automatic modes.