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Tuesday, December 15, 2009

DSLRs For Low Light

The combination of improved sensors, advanced processing engines and powerful algorithms makes the current lineup of pro DSLRs capable of a whole new kind of low-light photography

This Article Features Photo Zoom

It should be noted that a given image sensor has an innate sensitivity to light—a “native ISO”—and both higher and lower settings are achieved by digital processing. The processing necessary to produce higher ISOs increases noise, while the processing necessary to reduce ISO reduces dynamic range. So best image quality is produced at the sensor’s native ISO, which is generally the lowest one in the camera’s “normal” ISO range. As with film, how high you can go on the ISO scale depends in part on your idea of sufficient image quality for a given image—and it’s certainly wise to check out your camera’s high-ISO performance before shooting an important job. That said, today’s DSLRs produce much better image quality than film for any given ISO, as well as achieving ISOs not possible with film.

Digital offers advantages over film beyond far higher usable ISOs. First, with digital, you can easily set the ideal ISO for each image. That saves a lot of time and wasted film frames. Second, with digital, you can do a lot when processing RAW digital images to control noise, enhance dynamic range and color rendition, and adjust sharpening (it’s a very good idea to shoot RAW when using high ISOs, even though in-camera, high-ISO noise reduction is applied only to JPEGs). Third, with digital, you can shoot high-contrast scenes using HDR techniques and get an amazing dynamic range. But most importantly to action and low-light shooters, the newest DSLRs allow you to get remarkably good image quality at ISO settings beyond the wildest dreams of film photographers.

While medium-format DSLRs haven’t been known for their high-ISO performance, even that’s changing. Phase One’s Sensor+ technology uses a clever twist on the “binning” technique to let you choose super-high resolution or high resolution with good high-ISO performance. For example, the P65+ model can shoot 60.5-megapixel images at ISOs from 50-800 or 15-megapixel images at ISOs from 200-3200. (Combining groups of four pixels into single “super-pixels” increases sensitivity and reduces noise; Phase One’s method eliminates some of the problems of conventional binning techniques.)

Here’s a capsule look at today’s best low-light DSLRs, in alphabetical order by manufacturer.

Canon EOS-1D Mark IV

Canon EOS-1D Mark IV
Canon’s newest D-SLR wasn’t available at press time, so we haven’t had a chance to use it or check out the image quality. But this long-awaited successor to the Canon EOS-1D Mark III action camera boasts some amazing numbers. It features a new 16.1-megapixel, APS-H format (1.3x focal-length factor) Canon CMOS image sensor and dual DIGIC 4 processors, with a normal ISO range of 100-12,800. Should the need arise, you can expand that to 50 on the low end and all the way to 102,400 on the high end.

The EOS-1D Mark IV can shoot those 16.1-megapixel images at 10 fps, in bursts of up to 28 RAW or 121 Large JPEGs. As a 1-series EOS camera, it’s also rugged, with excellent weather- and dust-proofing, and a 300,000-cycle shutter. When you attach a higher-end L-series EF lens and the Speedlite 580EX II flash unit, the whole kit is weather-resistant. A 100% viewfinder, a 3.0-inch, 920,000-dot LCD monitor and Live View shooting with contrast-based or phase-detection AF are other assets.

A completely redesigned AF system with a new AI Servo (continuous-AF) algorithm should make the Mark IV Canon’s best action camera ever. We’re looking forward to trying it out when test cameras become available.

The Mark IV can shoot 1080p full HD video at 24, 25 or 30 fps, at ISO settings up to that remarkable 102,400. (It also can shoot 720p HD and 640x480p SD video at 60 or 50 fps.) Full manual control over aperture is provided in video shooting, when that’s desired. Images are recorded on CompactFlash or SD cards; use UDMA-compliant CompactFlash cards or SDHC cards for best performance.