Canon Rebel T1i Digital Camera Review - Canon DSLR

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	Resolution Summary
• Surprisingly poor sharpness • Acceptable levels of chromatic aberration and distortion • Low dynamic range, especially above ISO 200 • Image stabilization varies in its effectiveness
	Noise	Page 5 of 21	White Balance

Resolution (5.83)

The Rebel T1i surprised us by scoring very poorly on our resolution test, specifically in terms of sharpness. Yet even after testing multiple bodies and lenses, the inescapable fact appeared that images taken with the Rebel T1i are much softer than they should be. To test this accurately, we photograph a resolution chart at three focal lengths, with three apertures at each distance. From these photos, we ascertain image sharpness and chromatic aberration across nine areas of the lens, as well as distortion. Click here for more on how we test resolution.

Distortion
The distortion wasn't bad for this lens, floating below half a percent pin-cushioning at 37mm and 55mm. At 18mm it was significantly more noticeable, and a little on the high side at 2.8% barreling.

We were disappointed by the T1i's sharpness performance, across the entire gamut of focal lengths and apertures. Where most cameras will have a maximum line widths per picture height result of over 1500, the T1i peaked at 1360, with an average of only 868 line widths, and a minimum of around 550. This is much lower than we normally see. We suspected the poor results might be due to a hardware problem and asked Canon to supply us with a second camera that the company had tested to insure it was performing up to spec. In our retesting, though, the sharpness results didn’t improve.

The chromatic aberration wasn't bad though, generally on par with what we see on most inexpensive kit lenses.

Image Sharpness and Chromatic Aberration

f/3.5 f/9 f/22

18mm

At 18mm, the lens was at its sharpest, dead center with an aperture of f/3.5, though f/9 wasn't bad either. At this focal length, the sharpness tends to drop off the further from the center of the lens we tested. We saw the maximum chromatic aberration at this focal length at f/3.5, which was significantly higher than at any other setting. This patch of trouble occurred midway between the center and edge of the lens.

Image Sharpness and Chromatic Aberration

f/4.5 f/11 f/29

37mm

At 37mm, f/29 the image is decidedly on the soft side, never topping 700 line widths per picture height, but as the aperture opens, the overall sharpness improves. At this focal length the chromatic aberration isn't too bad; again, the f/29 setting causes the most trouble.

Image Sharpness and Chromatic Aberration

f/5.6 f/14 f/36

55mm

Once at the widest focal length, the really narrow apertures (in this case f/36) produce the absolute lowest sharpness we've seen, bottoming at a miserable 540 line widths per picture height. At this focal length, the chromatic aberration results are some of the lowest seen on this camera.

Resolution Score Comparison

NOTE: We updated our testing and scoring procedures in January 2009. For comparison purposes, we re-tested several cameras we'd reviewed in 2008, producing the scores shown in the chart above for the Canon Rebel XS and Nikon D90. However, the scores in the original reviews for these re-tested cameras remain unchanged, for consistency's sake.

Picture Quality & Size Options (8.75)

The T1i can shoot images in RAW, JPEG or both. JPEGs can be set to high or low quality settings in the three sizes listed below.

Image Size Options
Large	4752x3168
Medium	3456x2304
Small	2352x1568

Dynamic Range (5.65)

The T1i was decidedly lackluster in the dynamic range test, showing a marked decline after ISO 200, which gave it the lowest score among our comparison cameras. Dynamic range is a measure of a camera's ability to capture detail in both bright and dark areas of the same photo, so that detail is not lost into the shadows.

We test dynamic range by photographing a Kodak Stepchart at all available ISOs, and use Imatest to analyze the range of gray steps the camera captures. Click here for more on how we test dynamic range.

Dynamic Range

The Rebel T1i had a dynamic range of nearly seven stops at ISOs 100 and 200, but then it dropped off rapidly at the higher sensitivities.

Dynamic Range Comparison

Compared to other cameras at ISO 200, the T1i did worse than any of the others except the Pentax K2000, which in turn performed much better at higher ISOs. Overall, this is a disappointing result, and rightly puts the T1i at the bottom of the pack for this test.

Dynamic Range Score Comparison

The Rebel T1i has a d-range optimizer function called "Highlight Tone Priority"which will improve dynamic range, but may result in higher image noise.

Image Stabilization (6.62)

The T1i uses lens-based image stabilization, and shooting with the 18-55mm kit lens, we experienced mixed results. When it improved the resolution of captured photos it did so quite well, but is was a bit of a crapshoot as to when it that improvement would take place. Also, the T1i's overall sharpness problem meant that a relatively minor improvement resulting from image stabilization could be interpreted as a significant percentage improvement in our testing.

To test the capabilities of the image stabilization system, we shoot a slanted-line target at a number of shutter speeds, with Image Stabilization on and off, testing separately for horizontal and vertical stabilization. Our specially designed rig has two levels of vibration, a high shake setting that approximates the shake you’d find when shooting with one hand or when moving, and the low shake setting that’s close to what you would experience when standing still and holding the camera securely. Click here for more on how we test image stabilization.

Canon Rebel T1i Image Stabilization: Low Shake
Horizontal: Sharpness Vs Shutter Speed	Vertical: Sharpness Vs Shutter Speed

The charts above show the effectiveness of stabilization at our lower shake speed. While horizontally, it generally seems that the stabilization system will improve results, if only slightly, vertically the stabilization makes matters worse up until 1/15 of a second, where it produced a huge improvement.

Canon Rebel T1i Image Stabilization: High Shake
Horizontal: Sharpness Vs Shutter Speed	Vertical: Sharpness Vs Shutter Speed

At the higher shake speeds, image stabilization seems slightly more effective horizontally, though not at really high shutter speeds. Vertically the results are mixed, but stabilization never makes a huge difference one way or the other.

We only have stabilization data for two of the four comparison cameras, which are listed below. The T1i scores comparatively well in this section, but this is in part due to the relatively large percentage jump a small improvement produces when the top resolution is low to begin with, which is the case here.

Image Stabilization Score Comparison