Canon powerShot A3100 IS Performance, Timings, and Image Quality

PERFORMANCE
While the Canon A3100 IS doesn't look like earlier "A" series cameras, it uses essentially the same exposure system that made its predecessors popular. Exposure is automatically managed by the camera's DIGIC III processor, which combines most primary camera functions (image interpolation and processing, auto exposure, white balance, JPEG compression, gain control and power management) in one chip that improves efficiency and processing speed. In all exposure modes, the camera automatically optimizes all exposure parameters (aperture, shutter speed, sensitivity, WB, etc.) to consistently produce correctly exposed images.

Shooting Performance
Timing (speed of operation) is one of two most important considerations when assessing digital camera performance, and the other is image quality. The A3100 IS comes in right at the top when compared to its competitors, with the exception of the continuous shooting rate, in terms of operational speed.

Shutter Lag (press-to-capture, pre-focus)

AF Acquisition (press-to-capture, no pre-focus)

Continuous Shooting

The A3100 IS features the same TTL Contrast Detection 9-point AiAF (Advanced Intelligent Auto Focus) system as its predecessor. It has two AF modes - Face AiAF and Center. In all exposure modes, the camera analyzes the scene in front of the lens and then calculates camera to subject distance to determine which 9 AF point is closest to the primary subject (closest subject priority) and then locks focus on it. The A3100 IS's default face detection AF mode is linked directly to the camera's auto exposure and auto WB systems. The A3100 automatically finds, locks focus on, tracks and then optimizes exposure for up to nine faces or shooters can lock on a single face and track it through a crowd.

Even though Canon's DIGIC IV processor is showing up in many of its newer cameras, the A3100 IS's older DIGIC III processor still provides impressive performance including quicker start-up, faster AF and snappier shutter fire times than most its competitors. Users can also opt for the 1 AF point (center) AF for classic portraits or traditional landscapes. In low light, a focus assist beam helps illuminate the subject for more accurate focusing.

The built-in multi mode flash provides an acceptable selection of artificial lighting options, including auto, red-eye reduction, auto red-eye correction, flash on, flash off; FE lock, slow synchro and smart flash modes. According to Canon, the maximum flash range is about 13 feet (4 meters), which seems fairly accurate, based on my limited flash use. The A3100's flash recycle time is between 3 and 4 seconds. The Smart Flash Exposure mode adjusts flash exposure to match the subject and the shooting conditions to avoid dark facial shadows in outdoor portraits and for even lighting during macro shooting.

The A3100 IS's optical image stabilization system reduces blur by quickly and precisely shifting a lens element in the zoom to compensate for minor camera movement. Image stabilization allows users to shoot at shutter speeds up to three f-stops slower than would have been possible without it. Image stabilization can also be useful when shooting dimly lit indoor venues where flash is inappropriate.

According to Canon, the A3100 IS is good for about 240 exposures on its fully charged Lithium-ion power pack. That's substantially fewer exposures than the A1100 IS was capable of with a pair of re-chargeable NiMH AAs. The Canon PowerShot A3100 IS supports SD, SDHC, MMC, MMC+, HC MMC+ and the SDXC format (for memory cards larger than 32GB).

Lens Performance
When the A3100 IS is powered up, the 6.2mm-24.8mm, f/2.7-5.5 (35-140mm equivalent) 4x zoom extends from the camera body automatically, and when the camera is powered down, the lens retracts inside of the camera body and a built in iris-style lens cover closes to protect the front element. Zooming is fairly smooth and lens operation is relatively quiet. Minimum focusing distance (in macro mode) is 1.2 inches. The A3100 IS needs about 3 seconds to move the lens from the wide angle end of the zoom range to the telephoto end of the zoom range. Construction is seven elements in five groups with two single-sided aspherical elements.

The A3100 IS's zoom is surprisingly good and even though the lens displays some very minor corner softness, there's no vignetting (dark corners). Barrel distortion (at the wide-angle end of the zoom range) is minimal, which is impressive since barrel distortion is a common fault with small, highly complex camera zooms. Pincushion distortion is essentially invisible at the telephoto end of the zoom.

Video Quality
The 30 fps VGA (640 x 480) movie mode wasn't designed to compete with a dedicated video camera, but it will do nicely for generating email video attachments for friends and family. Like most cameras, the A3100 IS can't be zoomed while in video capture mode.

Image Quality
Image files produced by Canon's point-and-shoots are optimized for the bold bright hues and slightly hard contrast that many shooters refer to as Canon Color, and the A3100 IS doesn't stray far from its "family" trait. Default color is fairly accurate, with most colors coming pretty close to neutral.

Reds are a little warm, blues are a bit bright and greens are very vibrant, but purples are bluish. Most casual shooters won't consider these minor variations as color faults. Although there is a slight tendency toward overexposure, the A3100 IS produces dependably well-exposed, almost noise-free images when used outdoors in good light. Chromatic aberration is remarkably well-controlled, but some very minor color fringing is present, especially in the color transition areas between dark foreground objects and bright backgrounds.

Images from the A3100 IS are highly-detailed and surprisingly sharp, although in a small percentage of my shots the AF system didn't hit the mark and the IS system infrequently dropped the ball, which resulted in an occasionally blurry image. In bright contrasty lighting, highlight detail was occasionally blown-out. Overall, the A3100's image quality is slightly better than average for cameras in this class.

The A3100 IS provides users with a decent selection of white balance options, including auto, daylight, cloudy, tungsten, fluorescent and fluorescent H, and custom. Overall, the A3100 IS's auto WB system does a good job, but like all of Canon's consumer cameras, the auto WB setting produces colors that are noticeably warmer than real world colors under incandescent light.

Auto White Balance, 3200k incandescent light

Some DSLRs have a problem generating accurate greens and many consumer digicams have trouble getting purple just right. The A3100 IS suffers from this color interpolation malady. In the photo of the Crocuses, notice that the A3100 IS nailed the lavender in this group of early spring bloomers, but failed to get the deeper purple in the image of the Dwarf Irises right; the color is much too blue.

The A3100 IS provides a decent range of sensitivity options, including auto and user-set options for ISO 80 to 1600. ISO 80/ISO 100 images are indistinguishable in that they both show bright colors, slightly hard edged native contrast and very low noise levels. ISO 200 images were also very good, but with a little less pop.

ISO 80	ISO 80, 100% crop
ISO 100	ISO 100, 100% crop
ISO 200	ISO 200, 100% crop
ISO 400	ISO 400, 100% crop
ISO 800	ISO 800, 100% crop
ISO 1600	ISO 1600, 100% crop

At the ISO 400 setting, noise levels are noticeably higher and there's a perceptible loss of minor detail. ISO 800 images are very noisy, but they should be OK for lo-res email images and 3 x 5 inch or 4 x 6 inch prints. ISO 1600 images are way too noisy to be useful for anything beyond record shots.

Additional Sample Images