Sunday, August 23, 2009

Smart Cameras

By Mike Stensvold Published in SLRs
Smart Cameras

HD Video

An outgrowth of Live View, video is another feature long found in compact digital cameras, but only recently introduced to the D-SLR. Full 1920x1080 HD video amounts to more than two megapixels per frame, 27 times that of the 320x240 video found in most compact cameras and nearly 7 times that of 640x480 SD video. To handle that much information at 24 or 30 frames per second requires lots of processing power. Today, we finally have that power in the latest processors.

Nikon's D90 was the first D-SLR to offer video capability, followed shortly by Canon's EOS 5D Mark II. Several cameras now feature some form of HD video capture:

• The D90 and Nikon's new D5000 produce 1280x720 HD video (plus 640x424 and 320x216 standard video) at a "cinematic" 24 fps, with mono sound via a built-in microphone when desired.
• Canon's "semi-pro" EOS 5D Mark II shoots 1920x1080 full HD video or 640x480 standard video at 30 fps, with mono sound via a built-in microphone or stereo sound via an optional plug-in mic.
• Canon's new entry-level EOS Rebel T1i shoots 1920x1080 full HD video
at 20 fps, along with 1280x720 and 640x480 video at 30 fps.
• Panasonic's SLR-like Lumix DMC-GH1 can record 1920x1080 full HD video at 24 fps and 1280x720 video at 60 fps.
• Pentax's new K-7 can shoot 1280x720 HD video, as well as 1536x1024 and 640x416 3:2 video, all at 30 fps.


A number of new compact digital cameras also offer HD video, but D-SLRs provide several advantages. Since the image sensors in D-SLRs are much larger than those in compact digital cameras (and typical HD camcorders), you can obtain a cinema-like narrow depth of field not possible with the smaller sensors. Because the pixels on the larger D-SLR sensors are much larger, high ISO/low-light performance is much better. You also can use a wide range of interchangeable lenses to shoot movies with a D-SLR, while compact cameras and consumer HD camcorders come with built-in zoom lenses that limit your options.

Face Detection

Many newer digital cameras can identify human faces in a scene and adjust focus, exposure, white balance and even flash to render them optimally. The exact implementation varies from camera model to camera model (i.e., how many faces can be tracked, how you can override the camera's selection and how it employs focus, exposure and white-balance adjustments), but the feature is handy for people shots.

Now, face detection itself is gaining new features. Some cameras not only can detect faces in a scene, they can tell when those faces are smiling, alerting the photographer and even firing the shutter automatically when the smile occurs. Some smile-detection systems take multiple shots, so you can choose the best smile. A Blink feature warns you when a subject's eyes are closed, so you can retake the shot.

Some face-detection systems can differentiate between children and adults, allowing you to give priority to one or the other. Some can even recognize a specific person—you can register a favorite subject's face and name, and the camera will recognize that person when he or she appears in a shot, adjusting focus and exposure accordingly. Some even go the next step, allowing you to retrieve images based on who is in them. While current face-detection systems can detect only human faces, systems that can detect animal faces are in the works.
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