Canon EOS M Optics

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

The Canon EF-M 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. Sharpness and contrast are pretty good across most of the frame at 18mm and f/8, however there's moderate chromatic aberration and some minor softness visible in the corners. Results at full telephoto are also good at f/8, with good sharpness and contrast across much of the frame, and lower levels of chromatic aberration. Above average performance for an inexpensive kit lens.

Macro
A larger-than-average macro area with slightly soft detail.

The Canon EOS M's macro performance will of course depend entirely on the lens in use. With the 18-55mm STM lens set to 55mm, the Canon M captures a somewhat larger-than-average minimum area measuring 3.54 x 2.36 inches (90 x 60 millimeters). Details are a little soft in the center of the frame, and quite soft in the corners. (Most lenses have some softening in the corners at macro distances, so this is not unusual.)

Geometric Distortion
Higher than average barrel distortion at wide angle and moderate pincushion distortion at telephoto.

The Canon EF-M 18-55mm STM lens produces images with about 1.1 percent barrel distortion at full wide angle, which is higher than average and noticeable in some shots. At the telephoto end, there is about 0.3% pincushion distortion, which is lower than average and not very noticeable. The Canon EOS M 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
Moderately high chromatic aberration at wide angle. Some softening in the corners at both wide angle and telephoto.

Chromatic Aberration. Chromatic aberration in the corners with the Canon 18-55mm STM lens is moderate to moderately high at wide angle (18mm) when wide open, exacerbated somewhat by softness. 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. Chromatic aberration is however quite low across the frame at full telephoto (55mm). See below for how well the Canon EOS M's optional chromatic aberration correction works.

Corner Softness. The 18-55mm STM lens produces some soft corners when wide-open at maximum aperture. At full wide angle, corners on the left side of our test target are much softer than the right, though blurring doesn't extend very far into the frame, while the center of the image is quite sharp. At full telephoto, corners are sharper than at wide angle, but the ones on the left are still somewhat soft. Again, sharpness in the center is quite good at telephoto.

Vignetting. Vignetting or corner shading is not an issue in the above crops, but that's because the Canon EOS M's Peripheral Illumination Correction is enabled by default. See below for comparisons with it off.

f/8. Chromatic aberration in the corners is lower when the lens is stopped down to f/8, with colored pixels spread over a smaller area. Sharpness in the corners improved dramatically stopped down to f/8 at wide angle, however corner sharpness only improved slightly at full telephoto. As you can see, the Canon EOS M's Peripheral Illumination Correction over-corrected a bit at full telephoto, producing a slightly brighter corner crop than the center.

Chromatic Aberration Correction
The EOS M offers optional Chromatic Aberration Correction to reduce lateral C.A. with Canon lenses.

As you can see, the Canon EOS M'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. Bravo!

Peripheral Illumination Correction
Like other recent Canon DSLRs, the EOS M features Peripheral Illumination Correction feature to reduce vignetting or lens shading with Canon lenses.

The Canon EOS M 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 EOS M 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 EOS M.

Accuracy
Excellent accuracy from the LCD in record mode.

The Canon EOS-M's LCD viewfinder was accurate, with close to 100% coverage.