Canon SL2 Optics

Zoom
The new Canon EF-S 18-55mm f/4-5.6 IS STM kit lens offers a typical zoom range, with decent performance for its class.

The new and more compact Canon EF-S 18-55mm f/4-5.6 IS STM lens offers a typical optical zoom range for a kit lens of about 3.1x (about 29-88mm eq.). Optical performance is pretty good for an inexpensive kit lens across most of the frame at maximum wide angle (18mm), medium focal length (35mm) and full telephoto (55mm) at f/8, however it's not going to win any contests for sharpness and contrast against most pricier options. Still, it appears to perform better than the average kit lens. The above shots aren't very good for judging corner performance, distortion, etc., though, as they are meant mostly to illustrate zoom range; see below for how the lens performed in the lab.

Macro
An average minimum area (for an SLR kit lens), with very good detail. Flash throttled down fairly well.

The Canon Rebel SL2's macro performance will of course depend entirely on the lens used. With the new 18-55mm IS STM kit lens set to 55mm, the SL2 captured an average-sized minimum area for an SLR kit lens, measuring 3.17 x 2.12 inches (81 x 54 millimeters). Details are quite strong near the center of the frame, though corners are a little soft. (Most lenses have some softening in the corners at macro distances, though.) The Canon SL2's flash throttled down fairly well, producing a bright but even exposure with no detectable shadow from the lens barrel.

Geometric Distortion
Higher than average distortion at maximum wide angle and full telephoto from the 18-55mm IS STM kit lens.

The Canon EF-S 18-55mm f/4-5.6 IS STM lens produced images with just under one percent barrel distortion at wide angle, which is higher than average and noticeable in some shots. At the telephoto end, there was just under 0.6 % pincushion distortion, which is also higher than average and noticeable. The Canon SL2 does however offer built-in distortion correction. See below. Geometric 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 and Corner Sharpness
Low to moderately high chromatic aberration in the corners with the 18-55mm IS STM lens. The lens produces soft corners at wide angle and telephoto.

Chromatic Aberration. Chromatic aberration in the corners with our sample of the Canon 18-55mm f/4-5.6 IS STM lens is a little high at wide angle (18mm) but low at full telephoto (55mm), however most of it at wide angle is longitudinal (axial), which is difficult to correct. See below for how well the Canon SL2's lateral chromatic aberration correction works.

Corner Softness. Our sample of the 18-55mm f/4-5.6 IS STM lens produced some soft corners when wide-open at maximum aperture. At full wide angle, all four corners are a little soft and have lower contrast, though blurring doesn't extend very far into the frame and the center is quite sharp. At full telephoto, the bottom right corner is softest while sharpness in the other corners is similar or better though contrast still suffers. As is often the case, the lens isn't quite sharp in the center at full telephoto as it is at wide angle.

Vignetting. Vignetting or corner shading is only slightly noticeable when wide open at wide angle, but that's because the Canon SL2's Peripheral Illumination Correction is enabled by default. See below for comparisons with it disabled.

f/8: Chromatic aberration in the corners when stopped down to f/8 is low even at wide angle, while sharpness in the corners is improved, though corners are still not quite as sharp and contrasty as the center. Corner shading is all but eliminated at f/8 as well.

Overall, a better-than-average optical performance for an inexpensive kit lens.

Lens Aberration Corrections
The Canon SL2 offers a full range of digital lens aberration corrections.

Chromatic Aberration Correction
Chromatic Aberration Correction is enabled by default.

As you can see, the Canon SL2's Chromatic Aberration Correction feature was very effective at removing almost all the lateral chromatic aberration in our 18-55mm f/4-5.6 IS STM wide-angle test shot above. There wasn't much chromatic aberration to remove at full telephoto. Like most cameras, though, it's not very good at removing longitudinal (axial) chromatic aberration.

Diffraction Correction
Diffraction Correction is enabled by default.

Diffraction Correction simply applies stronger sharpening as the lens is stopped down to counteract softening from diffraction. There's not much diffraction to begin with at f/8 but if you look very closely, you'll see that slightly lower sharpening was applied with it disabled. Note that Diffraction Correction also increases sharpness slightly when shooting wide open as well, to help counteract the slight softening caused by the SL2's optical low-pass filter.

Distortion Correction
Distortion Correction is disabled by default.

While geometric distortion is higher that average from the new 18-55mm f/4-5.6 IS STM lens, with Distortion Correction enabled, it is greatly reduced. At wide angle, barrel distortion was only about 0.1% and at full telephoto, pincushion distortion was slightly overcorrected to only about a pixel's worth of barrel distortion.

Peripheral Illumination Correction
Peripheral Illumination Correction is enabled by default.

Peripheral Illumination Correction corrects for lens shading (commonly called "vignetting"), producing a more uniform exposure across the frame by compensating for the light fall-off seen with some lenses in the corners of the frame. Mouse over the On and Off links above to see the effect on the 18-55mm kit lens at wide angle and telephoto at maximum aperture. As you can see, there's quite a bit of corner shading with PIC disabled at both wide and telephoto at maximum aperture.

Notee that lens aberration correction is supported for Canon lens models, in both raw and JPEG workflows. For JPEG shooting, the correction is made at capture time, while raw shooters can access the function in Canon's Digital Photo Professional software. When using third-party lenses, Canon recommends disabling lens aberration corrections.

Accuracy
Below average accuracy from the optical viewfinder, very good accuracy from the LCD in Live View mode.

Testing with a low-distortion mid-focal length macro lens to minimize the effects of lens distortion, we measured the Canon SL2's optical viewfinder's coverage at close to 94%. This is a little lower than Canon's 95% specification, and the image is offset both vertically and horizontally with respect to the sensor, which is unfortunately quite common with optical viewfinders in consumer-oriented DSLRs (and even many prosumer models). Live View mode using the LCD is much more accurate, resulting in just over 99% coverage.