Sony MVC-CD250Sony adds features, and brings the price down on a 2 megapixel CD Mavica!<<Viewfinder :(Previous) | (Next): Exposure & Flash>> Page 5:OpticsReview First Posted: 02/20/2002 |
OpticsThe CD250 is equipped with a 3x, 6.4-19.2 mm lens (equivalent to a 41-123 mm lens on a 35mm camera), with a maximum aperture ranging from f/3.8 to f/3.9, depending on the lens' zoom position. Focus is controlled automatically, but fixed focus settings are also available, ranging from 0.5 meters to infinity. The bright orange autofocus assist light is helpful in limited lighting situations. You can enable or disable the AF assist light via a setup menu option.
The CD250's macro shooting mode produced great results, capturing a minimum area of 1.78 x 1.34 inches (45.28 x 33.96 millimeters) in my testing. Color and exposure looked good, but the corners of the images get fairly soft when you're shooting at the minimum range of 3 cm. (Do note that, like many cameras, the best macro performance is achieved when the zoom lens is set all the way to it's wide angle position.)
In other test shots, I saw a moderate amount of distortion from the CD250's lens, most noticeably some softness along the left side of the frame. The lens produced an approximate 0.85 percent barrel distortion at the wide-angle setting, and an approximate 0.35 percent pincushion distortion at telephoto, both numbers fairly typical of other cameras I've tested. That said, chromatic aberration was very low, as I only saw two very faint pixels of red coloration on the side of the target lines in the corners of the resolution target. (This distortion is most visible as a very slight colored fringe around the objects at the edges of the field of view on the resolution target.)
The lens also features filter threads to accommodate a variety of Sony lens
conversion kits. Unlike the CD400, since the CD250's lens does not telescope
out when the camera is turned on, normal 37mm-thread accessories can be used
directly with the camera. (No special barrel adapter is required.) When working
with a Sony lens conversion kit, you need to inform the camera (via the Setup
menu) that the lens is attached, so the camera's autofocus can allow for the
additional optical element.
The 2x Precision Digital Zoom function is enabled through the camera's Setup
menu, effectively increasing the CD250's zoom capabilities to 6x. When engaged,
digital zoom takes over once you've zoomed past the normal telephoto range.
You can see the change from optical to digital zoom by observing the marker
in the zoom range indicator on the LCD panel. As always though, I warn readers
that digital telephoto is not the same as optical zoom and that it causes
noticeable deterioration in image quality by adding excess noise and possibly
softening the image. That said, I've always experienced great results with
Sony's Precision Digital Zoom, as it does a nice job of holding on to image
detail and sharpness. Also, as we get into larger and larger CCD imagers,
digital zoom becomes useful at correspondingly larger file sizes. - With the
CD250 though, its 4 megapixel CCD means you can only achieve lossless digital
zooming with the 640x480 image size.
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