Canon T5i Optics

Zoom
The Canon EF-S 18-55mm IS STM lens offers a typical zoom range, with good performance for its class.

The Canon EF-S 18-55mm f/3.5-5.6 IS STM kit lens offers a typical optical zoom range of about 3.1x, with a 35mm-equivalent range of about 29-88mm because of the T5i's ~1.6x crop factor.

Sharpness and contrast look to be pretty good for a kit lens across much of the frame at 18mm and f/8, however moderate chromatic aberration is noticeable in the periphery of the image. Sharpness and contrast at full telephoto are also quite good at f/8, with lower levels of chromatic aberration.

This is above average far-field performance for an inexpensive kit lens, and the built-in image stabilization will come in handy for low-light shots. (Note that these shots are meant mainly to illustrate zoom ratio and are not ideal for judging optical performance; see below for how the lens performed in the lab.)

Macro
A small macro area (for an SLR kit lens), with good detail. Flash overexposed slightly.

Just like zoom ratio, the Canon EOS Rebel T5i's macro performance will of course depend entirely on the lens in use. With the 18-55mm STM lens set to 55mm, the Canon Rebel T5i captured a smaller-than-average size minimum area for an SLR kit lens, measuring 2.21 x 1.48 inches (56 x 38 millimeters). Details are quite good in the center of the frame, though corners are quite soft. (Most lenses have some softening in the corners at macro distances, though.) The Canon T5i's flash throttled down fairly well, producing a good, though just slightly overexposed image with no detectable shadow from the lens barrel.

Geometric Distortion
Higher than average barrel distortion at wide angle but low pincushion distortion at telephoto with the 18-55mm STM kit lens.

The Canon EF-S 18-55mm STM lens produced images with about 0.9 percent barrel distortion at wide angle, which is higher than average and noticeable in some shots. At the telephoto end, there was negligible distortion at less than 0.1% pincushion. The Canon T5i does not correct for geometric distortion in its JPEGs, as uncorrected RAW files have identical amounts. 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
Moderate to high chromatic aberration in the corners with the 18-55mm STM lens. Pretty good corner sharpness.

Chromatic Aberration. Chromatic aberration in the corners with the Canon 18-55mm STM lens is high and bright at wide angle (18mm) but moderately low at full telephoto (55mm). The amount and intensity of the color fringing reduces as you move toward the center of the image, to the point where it is very low at the center. See below for how well the Canon T5i's optional chromatic aberration correction works.

Corner Softness. The 18-55mm STM lens produced some slightly soft corners when wide-open at maximum aperture, but performance here was better than average. At full wide angle, the top left and bottom right corners are a bit softer than the remaining corners, though what little blurring there is does extend pretty far into the frame from the top corners. The other corners are pretty sharp, though, and the center is quite sharp. At full telephoto, the top corners are slightly soft while the bottom corners are pretty sharp, and the lens is sharp in the center.

Vignetting. Vignetting or corner shading is not an issue in the above crops, but that's because the Canon T5i's Peripheral Illumination Correction is enabled by default. (In fact, corner shading is slightly over-corrected.) See below for comparisons with it off.

f/8: Chromatic aberration in the corners is still moderate to high, while sharpness in the corners improves slightly when stopped down to f/8, though the same corners are still a touch softer than the center. As you can see, the Canon T5i's Peripheral Illumination Correction over-corrected again, producing noticeably brighter corner crops than the center.

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

Chromatic Aberration Correction
The Rebel T5i offers optional Chromatic Aberration Correction to reduce lateral C.A. with Canon lenses.

As you can see, the Canon T5i's Chromatic Aberration Correction feature was very effective at removing almost all the lateral chromatic aberration in our 18-55mm STM lens test shots above, though as a consequence, edges can look a little less distinct.

Peripheral Illumination Correction
The Canon T5i features Peripheral Illumination Correction feature to reduce vignetting or lens shading with Canon lenses.

Like most Canon DSLRs, the T5i provides what the company calls "Lens Peripheral Illumination Correction," which corrects for lens shading (commonly called "vignetting"), attempting to produce 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 Off and On links above to see the effect on the 18-55mm kit lens at wide-angle and telephoto at maximum aperture. PIC is enabled by default.

Peripheral Illumination Correction and Chromatic Aberration Correction are supported for over 85 different 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. From the factory, the T5i body ships with correction data for about 25 lens models. Canon's EOS Utility software allows correction data for lenses (including models as-yet unreleased) to be uploaded to the Canon T5i.

Accuracy
Average accuracy from the optical viewfinder, excellent 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 T5i's optical viewfinder's coverage at just over 95%. This matches Canon's 95% specification, but the image is offset both vertically and horizontally with respect to the sensor, which is unfortunately quite common with optical viewfinders in consumer-oriented models (and many prosumer models). Live View mode with the LCD is much more accurate with about 100% coverage, and of course the image isn't offset.