Sony DSC-W170 Optics

Zoom
Fairly good performance with the Sony W170's 5x optical zoom lens. Digital zoom performs well.

The Sony W170's 5x optical zoom lens covers a range equivalent to a 28-140mm zoom on a 35mm camera, which makes it wider as well as longer than most for this compact class of camera. Details are soft at full wide angle near the center, and some minor chromatic aberration is evident, and there is moderate blurring in the corners of the frame, especially the top right. Results at full telephoto are better, but with some minor chromatic aberration still visible. The camera's 2x digital zoom performed well, and though resolution and detail are compromised with the digital enlargement, there's still a lot of fine detail visible.

Macro
Soft details up close, with larger-than-average size macro area. Flash exposure was uneven.

The Sony W170's macro setting performed poorly, capturing a larger-than-average sized minimum area measuring 3.92 x 2.94 inches (100 x 75 millimeters). Resolution is good, but detail somewhat soft across the frame, and there's a significant amount of additional softening in the corners from the lens. (Most cameras have some softening in the corners in macro mode.) The flash coverage is uneven and it has a bit of trouble throttling down, so plan on using external lighting for the best results with the DSC-W170's macro settings.

Distortion
Moderate barrel distortion at wide angle, higher-than-average pincushion at telephoto.

The Sony W170's 0.8% barrel distortion at wide angle is about average, and quite noticeable. Still, a pretty good performance considering the fairly wide 28mm equivalent focal length. At the telephoto end, the W170's 0.6% pincushion distortion is much higher than average, and is also quite noticeable. Distortion is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide angle) or inward (like a pincushion -- usually at telephoto).

Chromatic aberration
Moderate at wide angle, exacerbated by softening in the corners; less noticeable at telephoto.

Chromatic aberration is moderate at wide angle, showing about 6-8 pixels of distinct, if not bright, coloration on either side of the target lines, which is exacerbated by corner softness. C.A. also extends fairly deep into the frame, but is not as evident there. Corners are sharper at telephoto, so C.A. is less noticeable at full telephoto focal length. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.)

Corner Sharpness
Moderate blurring in the top corners of the frame at wide angle, very good corner sharpness at telephoto.

The Sony W170 produced soft corners at the top of the frame at full wide angle, compared to sharp results in the center. The bottom corners were much sharper than the top. At full telephoto, only very minor blurring was noticeable in all four corners of the frame compared to the center.

Coverage
A very tight and inaccurate optical viewfinder (typical), though good accuracy from the W170's LCD monitor.

The Sony W170's optical viewfinder was quite tight and inaccurate (shifted), with only about 74% coverage at wide angle, and 80% coverage at full telephoto. This is, however, quite typical for a compact digicam's optical viewfinder. The LCD monitor was much more accurate, showing about 102% frame accuracy at wide angle and 98% at telephoto. LCD coverage is probably very close to 100%, but the lens's geometric distortion makes it difficult to frame and measure accurately.