Olympus Camedia C-60 ZoomOlympus packs a 6.1-megapixel CCD into an ultra-compact body, with a host of advanced features too.<<Viewfinder :(Previous) | (Next): Exposure & Flash>> Page 5:OpticsReview First Posted: 06/10/2004 |
Optics
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The
Olympus C-60 is equipped with an all-glass zoom lens, with seven elements in
six groups. The 3x, 7.8-23.4mm lens provides a focal length range equivalent
to a 38-114mm zoom on a 35mm film SLR. (That's a moderate wide angle to a normal
telephoto, slightly biased toward the telephoto end relative to the 35-105mm
zoom range that's most common.) Apertures range from f/2.8 to f/8, with the
maximum aperture setting ranging from f/2.8 to f/4.8 as the lens is zoomed from
wide angle to telephoto. The C-60's lens is a true variable-aperture design,
as the aperture can be changed in 1/3-stop increments. (Some cameras only provide
two fixed apertures, rather than a smoothly varying range, as does the C-60.)
Normal focusing distance extends from 1.6 feet (0.5 meters) to infinity. A Macro
setting focuses from 0.7 to 1.6 feet (0.2 to 0.5 meters), and a Super Macro
mode lets the C-60 focus as close as 1.6 inches (4cm). The Macro / Spot button
on the back panel adjusts the focus range for closeup subjects, and includes
an option for spot metering in either Macro or normal focusing mode.
The C-60's autofocus system is more sophisticated than most, using a "hybrid" approach to deliver much faster shutter response than the vast majority of consumer digicams. The "hybrid" designation means that focus is determined in two ways. First the distance is gauged with the passive sensors mounted under the flash, which brings the lens into approximate focus. From there, a through-the-lens contrast detection method takes over to refine the focus. A green circle lights solid in the viewfinder display whenever focus is set, and flashes if the camera is having trouble adjusting focus (as does the green LED lamp next to the optical viewfinder). The C-60 doesn't offer a manual focus option, and there's no autofocus-assist light, but it still managed to focus exceptionally well in dim lighting. During my low-light test, the C-60 managed to focus down to the 1/16 foot-candle limit of my test, a light level dark enough that you'd have to watch your footing while walking around. (For comparison, city night scenes under typical street lighting correspond to a light level of about one foot-candle.)
While the C-60's lens provides up to 3x optical zoom, the camera's 4x Digital Zoom increases that magnification to a maximum of 12x (albeit with the usual digital-zoom-induced quality degradations in the resulting images). Digital zoom is enabled through the Record menu and controlled by the Zoom Lever on top of the camera. Since digital zoom just crops out and enlarges the central pixels from the CCD's image, it directly trades resolution for magnification. This will result in very soft images if you're working at the camera's maximum five-megapixel file size, but can be useful if you only need 640 x 480 anyway. (For web or email use.)
Geometric distortion on the C-60 was fairly high at the wide-angle end, where I measured approximately 1.0 percent barrel distortion. The telephoto end fared much better, as I found only 0.1 percent barrel distortion there. The C-60's images were surprisingly sharp from corner to corner at wide and medium focal lengths, but somewhat soft there at telephoto focal lengths, and there was quite a bit of chromatic aberration at the wide angle setting, with fairly bright red/green fringes around the target objects in the corners of the frame. (This distortion is visible as slight colored fringes around the objects at the edges of the field of view on the resolution target.) Overall though, a pretty good performance, better than I'd normally expect from a compact lens design.
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