By Joe Kashi, for the Redoubt Reporter
Given a choice, most people prefer high-quality camera systems that are small, light and highly portable. If wondering about possible trade-offs in quality, though, how does the image quality of the best new compact-system cameras compare with the best midrange digital SLR cameras using larger APS-C sensors? Surprisingly well.
As a sequel to our recent discussions of current dSLR cameras, this week we’ll directly compare Pentax’s K-5 and the new Olympus OM-D. (Also termed the E-M5 by Olympus. Don’t ask me why.) They’re among the best, if not the best, camera systems in their respective categories.
Even though it’s a 2010 design, there’s a consensus that Pentax’s K-5 dSLR has some of the best potential image quality of any currently available camera using a standard APS-C sensor. In fact, when used with excellent lenses and good technique, enlarged images made with a K-5 approach the quality of images made with many full-frame cameras.
Similarly, Olympus’ recently introduced 16-megapixel OM-D is, by general consensus, one of the two or three best currently available compact-system cameras. In the near future, Panasonic will likely announce a prolevel Micro Four-Thirds camera that rivals the OM-D. However, at this time, there’s nothing tangible from Panasonic that’s directly comparable to the OM-D in practice, or even as paper specifications.
Fujifilm’s 16-megapixel X-Pro1 and Sony’s 24-megapixel NEX-7, both APS-C compact-system cameras, can provide excellent quality images that, under the right circumstances, are quite comparable to the OM-D. However, both the Fujifilm and Sony systems are significantly hampered by the limited number of top-end lenses available for those unique lens mounts. The Micro Four-Thirds system shared by Olympus and Panasonic, on the other hand, has an abundance of fairly priced, excellent lenses. In the end, I found, excellent optics are the single most important factor affecting optimum image quality.
Both the Fujifilm X-Pro1 system and Sony’s NEX-7 are also hampered by the lack of image stabilization when used with most lenses. That lack of any image stabilization is a real deal-breaker for many knowledgeable photographers.
Image stabilization is probably the most useful secondary innovation that accompanied digital photography. Effective image stabilization hardware allows you to use lower shutter speeds and, thus, lower ISO sensitivities where image quality is best. As an example, that means you can use ISO 200 in situations where unstabilized cameras must use ISO 1,600 to ISO 3,200 to avoid camera shake. Thus, effective stabilization is a major image quality advantage, more useful in many situations than using a larger sensor, at least with subjects that are not moving quickly.
Olympus’ OM-D uses a unique and highly effective image-stabilization system — the sensor itself is suspended in a magnetic field that almost instantly corrects for shake and rotation on five axes: the usual left-right X axis, the up-down Y axis, and three rotational directions. To my knowledge, no other camera corrects for image blurring caused by rotation. As a result, the OM-D can effectively correct for a great deal of complex camera shake, even at very slow shutter speeds.
Another important advantage of current Olympus cameras is that vendor’s very fast and accurate “contrast detection” autofocus system. Digital SLR cameras generally use “phase detection” autofocus hardware, which requires a separate focus sensor in the viewfinder. Until recently, phase detection autofocus was preferred because it was noticeably faster. However, the accuracy of phase detection focus is critically dependent on near-perfect assembly and calibration of that autofocus hardware. As a result, phase detection autofocus hardware is very susceptible to misalignment in manufacture and to later jarring.
Generally, compact-system cameras like the OM-D use a different sort of autofocus mechanism, “contrast detection,” which works directly with the sensor’s image. In theory, contrast detection autofocus is simpler, more rugged and more accurate. Until recently, though, contrast detection autofocus was too slow. Both Olympus and Panasonic have solved that limitation by introducing contrast detection hardware that’s as fast or faster than dSLR cameras.