Canon S95 Optics

Zoom
A fairly wide, 3.8x optical zoom lens with very good performance.

The Canon PowerShot S95's lens remains the same as the S90's, covering the equivalent of a 28-105mm zoom on a 35mm camera with a maximum aperture range of f/2.0-4.9 and a fairly typical zoom ratio of about 3.8x. Details are pretty good across the frame at full wide-angle, with only minor blurring and coma distortion in the corners, though mild to moderate levels of chromatic aberration are visible in the corners and edges. Results at full telephoto are very good with strong detail across the frame and only small amounts of corner softness and chromatic aberration. The Canon S95's digital zoom does a pretty good job of maintaining fine detail despite the typical blurring and loss of resolution associated with digital zoom. (Note the above digital zoom shot was taken at approximately 2.3x, not the maximum 4x supported.)

Macro
A slightly larger than average macro area, with excellent detail and resolution. Flash had some difficulty throttling down, and is partially blocked by lens.

The Canon PowerShot S95's macro setting captured a slightly larger than average area of 2.50 x 1.88 inches (64 x 48 millimeters). Detail and resolution were both very good, though there's some softening in the corners from field curvature of the lens. (Most cameras have some softening in the corners in macro mode. What we can see here is a bit better than average.) The Canon S95's flash had some difficulty throttling down at this distance, causing overexposure where the flash wasn't blocked by the lens. The overexposure plus the shadow from the lens resulted in a very unevenly lit image. Plan on using external lighting for the closest macro shots with the S95.

Distortion
Lower than average barrel distortion at wide-angle in JPEGs; very high at wide-angle in RAW files. Low distortion at telephoto.

JPEG: The Canon S95's 0.5% barrel distortion at wide-angle is actually fairly low compared to the average digital camera, especially considering its wide 28mm equivalent focal length (see below for the explanation). The distortion is however still noticeable in some shots. At the telephoto end, the S95's less than 0.2% barrel distortion is a little unusual as we'd normally expect to see pincushion distortion at telephoto. The amount is quite low at around 0.2%, and is only slightly noticeable in some images. This 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).

Raw: When converting RAW files using dcraw (which doesn't apply any distortion correction), barrel distortion at wide-angle is much higher, at about 3.5%. Distortion at full telephoto is about the same as the in-camera JPEG, so no correction was performed by the camera at the telephoto end. Note that dcraw doesn't fully support the Canon S95's files at the time of writing (late September 2010), so we haven't included links to full resolution versions here. Canon's bundled Digital Photo Professional software automatically corrects for geometric distortion, producing results very similar to in-camera JPEGs.

Chromatic Aberration and Corner Softness
C.A. is moderate at wide-angle, and mild at telephoto. Mild to moderate blurring in the corners of the frame at wide-angle at maximum aperture, but good corner sharpness at telephoto.

Chromatic Aberration. Chromatic aberration is moderate and slightly bright at wide-angle. The color fringing doesn't extend very far into the frame, though. At telephoto, chromatic aberration is lower and therefore less noticeable. As mentioned previously, dcraw doesn't fully support the S95's files yet (it doesn't interpolate color correctly), and other converters tend to apply some correction automatically, so it's difficult to tell if the Canon S95 is applying some correction for C.A. in its JPEGs. Chromatic aberration is a type of distortion visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.

Corner Softness. The Canon S95's lens produced mild to moderate corner softness at full wide-angle. Blurring was stronger in the left corners with the bottom left being the softest, but softness didn't extend very far into the frame. The right corners weren't as soft, and the center was quite sharp. All four corners at full telephoto were pretty sharp. Again, the center was sharp, though contrast is a touch lower than at wide-angle. Overall results are pretty good, especially considering that these shots were taken at maximum aperture, which is relatively fast at wide-angle (f/2.0). That's because corner sharpness generally improves as the lens is stopped down to smaller apertures.

Here are the same wide-angle corners at f/5.6, showing less blurring but about the same amount of C.A. compared to wide-open:

Coverage
Excellent accuracy from the LCD monitor.

The Canon PowerShot S95's LCD monitor showed just over 100% coverage accuracy at wide-angle, and 100% at telephoto. Excellent results here.