COLOR
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Canon EOS Rebel T4i (EOS 650D) Photo Gallery.
source : imaging-resource.com
Saturation & Hue Accuracy
Very good saturation and excellent hue accuracy.
Saturation. The Canon EOS Rebel T4i produces images with
fairly accurate saturation levels. Strong reds, oranges, dark greens and
dark blues are pushed a little, while yellow and cyan are slightly
muted. The mean saturation of 108.3% (8.3% oversaturated) at base ISO is
not too pumped yet not too dull, and saturation remains fairly
consistent over the ISO range except at ISO 25,800 where it drops off
noticeable. Most consumer digital cameras
produce color that's more highly saturated (more intense) than found in
the original subjects. This is simply because most people like their color
a bit brighter than life.
Skin tones. The Canon T4i produced pleasing,
natural-looking Caucasian skin tones in our tests when using both manual
and auto white balance settings. Darker skin tones show a small nudge
toward orange, but good results overall. Where oversaturation is most
problematic is on Caucasian skin tones, as it's very easy for these "memory
colors" to be seen as too bright, too pink, too yellow, etc.
Hue. The Canon Rebel T4i's hue accuracy is excellent, much better than average. There are the usual shifts in cyan toward blue (actually quite small), red toward orange, and orange toward yellow, but all are fairly minor. (The cyan to blue shift is very common among the digital cameras we test; we think it's a deliberate choice by camera engineers to produce better-looking sky colors.) Average "delta-C" color error at base ISO is only 3.23, which is outstanding, one of the best scores we've recorded to date. Hue is "what color" the color is.
Saturation Adjustment
The Canon EOS Rebel T4i offers a total of nine saturation settings, four above and four below the default saturation. This covers a very wide range of saturation levels, and as it should, the Canon T4i's saturation adjustment affects only saturation, leaving the contrast of images more or less unaltered. (In some cameras, saturation tends to affect contrast, and vice versa.) The fine steps between settings mean you can program the camera to just the level of saturation you prefer. As usual for Canon, well done.
The table above shows alternate settings including the default
as well as the two extreme saturation settings. Click on any thumbnail
above, then click again to see the full-sized image.
Very good saturation and excellent hue accuracy.
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ISO Sensitivity
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| In the diagram above, the squares show the original color, and the circles show the color that the camera captured. More saturated colors are located toward the periphery of the graph. Hue changes as you travel around the center. Thus, hue-accurate, highly saturated colors appear as lines radiating from the center. Mouse over the links above to compare ISOs, and click to load a larger version. | ||||
Hue. The Canon Rebel T4i's hue accuracy is excellent, much better than average. There are the usual shifts in cyan toward blue (actually quite small), red toward orange, and orange toward yellow, but all are fairly minor. (The cyan to blue shift is very common among the digital cameras we test; we think it's a deliberate choice by camera engineers to produce better-looking sky colors.) Average "delta-C" color error at base ISO is only 3.23, which is outstanding, one of the best scores we've recorded to date. Hue is "what color" the color is.
Saturation Adjustment
The Canon EOS Rebel T4i offers a total of nine saturation settings, four above and four below the default saturation. This covers a very wide range of saturation levels, and as it should, the Canon T4i's saturation adjustment affects only saturation, leaving the contrast of images more or less unaltered. (In some cameras, saturation tends to affect contrast, and vice versa.) The fine steps between settings mean you can program the camera to just the level of saturation you prefer. As usual for Canon, well done.
| Saturation Adjustment Examples | ||||
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| -4 | -2 | 0 | +2 | +4 |
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SENSOR
Exposure and White Balance
Indoors, incandescent lighting
Auto and Incandescent settings both struggled with household incandescent lighting, though Manual white balance worked well. Slightly higher than average exposure compensation required.
Indoors, under incandescent lighting, the Canon EOS Rebel T4i's Auto and Incandescent white balance settings struggled, both producing very warm red/orange color casts. Unfortunately, this is common among cameras we've tested, but disappointing nonetheless. The Manual setting produced the most accurate results, though just slightly cool overall. The Rebel T4i doesn't offer a Kelvin temperature setting like its more expensive siblings, but like all recent Canon SLRs, you can shift color balance toward more or less green vs magenta or blue vs amber, using a +/-9 step grid format display. The Canon Rebel T4i required +0.7 EV exposure compensation for this shot, which is slightly higher than the +0.3 EV average among the cameras we've tested. (Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.)
Outdoors, daylight
Color and saturation are very good, though a tendency towards slightly cool color balance and slightly high contrast under harsh lighting. Slightly below average exposure accuracy.
Outdoors, the Canon EOS Rebel T4i tended toward a slightly cool
color balance, though overall color was generally very good. The Canon
Rebel T4i required +1.0 EV exposure compensation to keep the mannequin's
face bright, a little more than the typical +0.7 EV we're accustomed to
using for our "Sunlit" portrait shot. The Canon T4i's default contrast
is a little high, producing some washed-out highlights and dark shadows
under the deliberately harsh lighting of our "Sunlit" portrait test
shown above left, though the camera's contrast, Auto Lighting
Optimizer and Highlight Tone Priority settings do help with high
contrast scenes like these. See below for examples of this. The
Far-field shot (above right) was also a touch cool, and exposure a bit
dim, though the camera did a good job of avoiding blown highlights at
default exposure. Deep shadows however are quite dark and somewhat
noisy.
Indoors, incandescent lighting
Auto and Incandescent settings both struggled with household incandescent lighting, though Manual white balance worked well. Slightly higher than average exposure compensation required.
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| Auto White Balance +0.7 EV |
Incandescent White Balance +0.7 EV |
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| Manual White Balance +0.7 EV |
Indoors, under incandescent lighting, the Canon EOS Rebel T4i's Auto and Incandescent white balance settings struggled, both producing very warm red/orange color casts. Unfortunately, this is common among cameras we've tested, but disappointing nonetheless. The Manual setting produced the most accurate results, though just slightly cool overall. The Rebel T4i doesn't offer a Kelvin temperature setting like its more expensive siblings, but like all recent Canon SLRs, you can shift color balance toward more or less green vs magenta or blue vs amber, using a +/-9 step grid format display. The Canon Rebel T4i required +0.7 EV exposure compensation for this shot, which is slightly higher than the +0.3 EV average among the cameras we've tested. (Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.)
Outdoors, daylight
Color and saturation are very good, though a tendency towards slightly cool color balance and slightly high contrast under harsh lighting. Slightly below average exposure accuracy.
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| Auto White Balance, +1.0 EV |
Auto White Balance, 0 EV |
RESOLUTION
Very high resolution, 2,000 ~ 2,100 lines of strong detail.
Our laboratory resolution chart showed the Canon Rebel T4i's
images with sharp, distinct line patterns down to about 2,000 lines per
picture height horizontally and about the same vertically. Extinction of
the pattern occurred just past 3,200 lines horizontally and at about
3,000 lines vertically. Adobe Camera Raw converted .CR2 files show
slightly more resolution than the in-camera JPEG, perhaps 100 lines,
though complete extinction of the pattern was extended well past 3,200
lines in both directions in the converted files. While ACR was able to
extract more detail, it also produced more color moire and false colors,
especially in vertical lines. Use these numbers to compare with other
cameras of similar resolution, or use them to see just what higher
resolution can mean in terms of potential detail.
Very high resolution, 2,000 ~ 2,100 lines of strong detail.
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| Strong detail to 2,000 lines horizontal In-Camera JPEG |
Strong detail to 2,000 lines vertical In-Camera JPEG |
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| Strong detail to 2,100 lines horizontal ACR Converted RAW |
Strong detail to 2,100 lines vertical ACR Converted RAW |
SHARPNESS & DETAIL
Good sharpness and loads of detail with a sharp lens. Some minor detail loss to noise reduction processing even at low ISOs.
Sharpness. The Canon EOS Rebel T4i's 18-megapixel sensor
captures excellent image detail when coupled with a good lens, though
some minor edge-enhancement artifacts are visible around high-contrast
edges, as shown in the crop above left. (The above crop of our Far-field
House shot was taken with Canon's very sharp 16-35mm f/2.8L II USM lens
at f/8.) Edge enhancement creates the illusion of sharpness by
enhancing colors and tones right at the edge of a rapid transition in
color or tone.
Detail. The crop above right shows some detail loss due to noise suppression in darker areas and in areas with low contrast, but no more than we're accustomed to seeing at these resolutions. Good performance for an 18-megapixel APS-C sensor. (The crop above of the hair taken with our very sharp Sigma 70mm f/2.8 reference lens.) Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears.
Raw vs In-Camera JPEGs
As mentioned above, the Canon T4i does an excellent job of capturing sharp, detailed JPEGs when coupled with a sharp lens, but as is usually the case, slightly more detail can be preserved by carefully processing its raw files.
In the table above, mousing over a link at the bottom will load
the corresponding crop in the area above, and clicking on the link will
load the full resolution file. Examples include in-camera Fine JPEG, the
matching raw file processed through Canon's Digital Photo Professional
(DPP) software using default settings, and finally, the same raw file
processed through Adobe Camera Raw (ACR), then sharpened in Photoshop
using 300% unsharp masking with an 0.3 pixel radius.
Canon's DPP software produced images similar to in-camera JPEGs, perhaps with just slightly better detail. Images processed through ACR show more fine detail than the DPP conversions, but also show more noise at default settings, which is not unusual. You may want to experiment with ACR's noise reduction settings to find the detail vs noise trade-off you're looking for. Regardless, the Canon T4i is clearly a camera that carries a lot of detail in its raw files.
Good sharpness and loads of detail with a sharp lens. Some minor detail loss to noise reduction processing even at low ISOs.
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| With default sharpening settings, the Canon Rebel T4i's JPEG files show some minor sharpening artifacts. |
Subtle detail: Hair Noise suppression blurs detail in areas of subtle contrast, as in the darker parts of the model's hair here. |
Detail. The crop above right shows some detail loss due to noise suppression in darker areas and in areas with low contrast, but no more than we're accustomed to seeing at these resolutions. Good performance for an 18-megapixel APS-C sensor. (The crop above of the hair taken with our very sharp Sigma 70mm f/2.8 reference lens.) Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears.
Raw vs In-Camera JPEGs
As mentioned above, the Canon T4i does an excellent job of capturing sharp, detailed JPEGs when coupled with a sharp lens, but as is usually the case, slightly more detail can be preserved by carefully processing its raw files.
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Canon's DPP software produced images similar to in-camera JPEGs, perhaps with just slightly better detail. Images processed through ACR show more fine detail than the DPP conversions, but also show more noise at default settings, which is not unusual. You may want to experiment with ACR's noise reduction settings to find the detail vs noise trade-off you're looking for. Regardless, the Canon T4i is clearly a camera that carries a lot of detail in its raw files.
ISO & NOISE PERFORMANCE
Very good detail versus noise up to ISO 1,600, though detail suffers at higher ISOs.
The Canon EOS Rebel T4i's high ISO performance is pretty good,
very similar to the Canon T3i's. Images are quite clean at ISOs 100
through 400, with just a tiny amount of luminance noise seen in the
shadows, as well as what looks to be chroma noise in the darker strands
of hair. Noise "grain" is slightly more evident at ISO 800, but detail
remains very strong despite some minor blurring due to noise reduction.
At ISO 1,600 is of course noisier, but fine detail is still very good.
At ISO 3,200 noise grain becomes coarser, blurring stronger and chroma
noise more apparent, resulting in a more noticeable drop in detail. ISO
6,400 is quite grainy with obvious chroma noise, but there is some fine
detail left. Noise and the effects of noise reduction working hard to
keep it under control really become apparent at ISO 12,800 and
especially 25,600, with strong blurring and obvious chroma blotching,
along with a drop in saturation.
There are also what look to be demosaicing errors in areas of
fine vertical detail and high local contrast, such as the strange
diagonal bands in the strands of hair on the model's forehead at lower
ISOs (see ISO 100 crop at right). We've seen these artifacts in our
indoor portrait JPEG images from other Canon SLRs, as well as hints of
them in JPEGs from other manufacturers, so they're not that unusual. The
aberrations are very subtle to be sure, but they're something to be
aware of if you plan to make very large prints of similar subject matter
from JPEGs. They don't appear in raw files processed with a good
converter such as Adobe Camera Raw.
Overall though, a good performance, perhaps just slightly better detail retention compared to the T3i at higher ISOs. Noise is however generally a little higher than competing models. See the Print Quality section below for our evaluation of maximum print sizes at each ISO setting.
A note about focus for this shot: We shoot this image at f/4, using one of three very sharp reference lenses (70mm Sigma f/2.8 macro for most cameras, 60mm f/2.8 Nikkor macro for Nikon bodies without a drive motor, and Olympus Zuiko 50mm f/2.0 for Four Thirds and Micro Four Thirds bodies). To insure that the hair detail we use for making critical judgements about camera noise processing and detail rendering is in sharp focus at the relatively wide aperture we're shooting at, the focus target at the center of the scene is on a movable stand. This lets us compensate for front- or back-focus by different camera bodies, even those that lack micro-focus adjustments. This does mean, though, that the focus target itself may appear soft or slightly out of focus for bodies that front- or back-focused with the reference lens. If you click to view the full-size image for one of these shots and notice that the focus target is fuzzy, you don't need to email and tell us about it; we already know it. :-) The focus target position will simply have been adjusted to insure that the rest of the scene is focused properly.
Very good detail versus noise up to ISO 1,600, though detail suffers at higher ISOs.
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Default High ISO Noise Reduction
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| ISO 100 | ISO 200 | ISO 400 |
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| ISO 800 | ISO 1,600 | ISO 3,200 |
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| ISO 6,400 | ISO 12,800 | ISO 25,600 |
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Overall though, a good performance, perhaps just slightly better detail retention compared to the T3i at higher ISOs. Noise is however generally a little higher than competing models. See the Print Quality section below for our evaluation of maximum print sizes at each ISO setting.
A note about focus for this shot: We shoot this image at f/4, using one of three very sharp reference lenses (70mm Sigma f/2.8 macro for most cameras, 60mm f/2.8 Nikkor macro for Nikon bodies without a drive motor, and Olympus Zuiko 50mm f/2.0 for Four Thirds and Micro Four Thirds bodies). To insure that the hair detail we use for making critical judgements about camera noise processing and detail rendering is in sharp focus at the relatively wide aperture we're shooting at, the focus target at the center of the scene is on a movable stand. This lets us compensate for front- or back-focus by different camera bodies, even those that lack micro-focus adjustments. This does mean, though, that the focus target itself may appear soft or slightly out of focus for bodies that front- or back-focused with the reference lens. If you click to view the full-size image for one of these shots and notice that the focus target is fuzzy, you don't need to email and tell us about it; we already know it. :-) The focus target position will simply have been adjusted to insure that the rest of the scene is focused properly.
Extremes: Sunlit, dynamic range and low light tests
Very high resolution with strong overall detail, but somewhat high default contrast and unremarkable dynamic range. Highlight Tone Priority and contrast adjustment options do a great job of dealing with tough lighting. Very good low-light performance.
The Canon EOS Rebel T4i produced moderately high contrast with some washed-out highlights and deep shadows under the deliberately harsh lighting of the test above. The mannequin's face was too dim at the +0.3 EV and +0.7 EV settings, so we preferred the image with +1.0 EV exposure compensation. This resulted in more clipped highlights in the shirt and flowers than we're used to seeing from an APS-C sensor lately, indicating only average dynamic range compared to the best of recent competitors. Shadow detail was however pretty good, though somewhat noisy. Bottom line: while dynamic range isn't bad, the Canon T4i struggled a bit with this difficult shot compared to recent state-of-the-art peers.
Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here. In actual shooting conditions, be sure to use fill flash in situations like the one shown here; it's better to shoot in open shade whenever possible.)
Contrast Adjustment
We really like it when a camera gives us the ability to adjust contrast and saturation to our liking. It's even better when those adjustments cover a useful range, in steps small enough to allow for precise tweaks. As was the case with its saturation adjustment, the Canon T4i's contrast setting meets both challenges very well.
At its lowest contrast setting, the Canon T4i did an excellent job
of preserving highlight detail, maintaining fairly natural-looking skin
tones, and holding nice detail in the shadows. Overall, very good
results here, especially when the contrast setting is tweaked.
The Canon Rebel T4i's contrast-adjustment control offers a very
broad range of control in usefully fine gradations, and does a good job
of adjusting contrast without affecting color saturation in the process.
(As noted earlier regarding saturation adjustment, something that not
all cameras manage to do.)
Highlight Tone Priority
The Canon EOS Rebel T4i's Highlight Tone Priority (HTP) option did an excellent job of preserving highlight detail, as shown below. (Mouse over the Off and On links to load the corresponding thumbnail, histogram and crops.)
Both shots above were captured at the same exposure, the only difference being that HTP was enabled for the second shot which necessarily increases the ISO to 200; part of how HTP works. The result is evident in the histograms and thumbnails above, clearly showing the superior highlight preservation when HTP is enabled, while shadow brightness is left relatively untouched. If you look closely at shadows however, you'll notice an increase in noise is the price you pay when ISO is boosted from 100 to 200. Except in the very deepest shadows, though, overall noise is low enough at ISO 200 that this is really a negligible trade-off for all but the most critical applications.
Automatic Lighting Optimization
Like the 60D, T2i and T3i, the Canon Rebel T4i offers three selectable levels of Automatic Lighting Optimization (ALO), plus Off. In fully automatic and Creative Auto exposure modes, ALO is automatically enabled. All four shots below were taken with the same default exposure settings. Mouse over the links below to load the associated thumbnail and histogram, and click on the links to load full resolution images.
As you can see above, ALO has the effect of shifting shadows and
mid-tones in the histograms to the right, brightening shadows and indeed
most of the image without clipping too many additional highlights. ISO
is not boosted for ALO so increased noise is not an issue, though it may
be slightly more visible in shadows that have been boosted
significantly.
Face Detection
Just like most point & shoot cameras these days, the Canon EOS Rebel T4i has the ability to detect faces in Live View mode, and adjust exposure and focus accordingly.
As you can see from the examples above, it works well, as the
center image with face detection enabled is much better exposed for the
face than the left image where face detection was not employed. Full
Auto mode (right) however wasn't much better than Aperture Priority,
despite selecting a larger aperture than we normally use for this shot
(f/4.5 vs f/8).
Dynamic Range
A key parameter in a digital camera is its Dynamic Range, the range of brightness that can be faithfully recorded. At the upper end of the tonal scale, dynamic range is dictated by the point at which the RGB data "saturates" at values of 255, 255, 255. At the lower end of the tonal scale, dynamic range is determined by the point at which there ceases to be any useful difference between adjacent tonal steps. Note the use of the qualifier "useful" in there: While it's tempting to evaluate dynamic range as the maximum number of tonal steps that can be discerned at all, that measure of dynamic range has very little relevance to real-world photography. What we care about as photographers is how much detail we can pull out of the shadows before image noise becomes too objectionable. This, of course, is a very subjective matter, and will vary with the application and even the subject matter in question. (Noise will be much more visible in subjects with large areas of flat tints and subtle shading than it would in subjects with strong, highly contrasting surface texture.)
What makes most sense then, is to specify useful dynamic range in terms of the point at which image noise reaches some agreed-upon threshold. To this end, Imatest computes a number of different dynamic range measurements, based on a variety of image noise thresholds. The noise thresholds are specified in terms of f-stops of equivalent luminance variation in the final image file, and dynamic range is computed for noise thresholds of 1.0 (low image quality), 0.5 (medium image quality), 0.25 (medium-high image quality) and 0.1 (high image quality). For most photographers and most applications, the noise thresholds of 0.5 and 0.25 f-stops are probably the most relevant to the production of acceptable-quality finished images, but many noise-sensitive shooters will insist on the 0.1 f-stop limit for their most critical work.
JPEG.
The graph at right (click for a larger version) was generated using
Imatest's dynamic range analysis for an in-camera Canon Rebel T4i JPEG
file with a nominally-exposed density step target (Stouffer 4110). At
default camera settings and base ISO, the graph shows 11.1 f-stops of
total dynamic range, with 7.41 f-stops at the "High" Quality level.
These are decent numbers for a JPEG, though somewhat lower than some
recent competitors. Compared to the Canon T3i which uses a similar
sensor with an older processor, the T4i scored slightly higher at the
High Quality level (7.41 vs 7.31 f-stops), and significantly higher in
total dynamic range (11.1 vs 9.95 f-stops). Note though that this
measurement has a margin of error of about 1/3 f-stop, so differences of
less than 0.33 can be ignored.
Raw. The
graph at right is from the same Stouffer 4110 stepchart image captured
as a raw (.CR2) file, processed with Adobe Camera Raw using the Auto
setting. The Canon T4i's raw file scored 0.8 f-stop more in total
dynamic range (11.9 vs 11.1 f-stops) but the score at the highest
quality level increased only 0.15 f-stops from 7.41 to 7.56, which is an
insignificant improvement and below average these days. Results are
very similar to those of the Canon T3i at the High Quality level (7.56
vs 7.63 f-stops), though the total dynamic range score was higher like
the JPEG, at 11.9 vs 11.1 f-stops. Like all recent Canon SLRs, these
scores are somewhat below average for a modern APS-C sensor. As always,
it's worth noting here is that ACR's default noise reduction settings
reduced overall noise somewhat (see the plot in the lower left-hand
corner) relative to the levels in the in-camera JPEG, which would tend
to boost the dynamic range numbers for the High Quality threshold, but
notice that pixel noise in darker midtones and shadows is actually
higher than the JPEG. Also, the extreme highlight recovery being
performed by ACR here would likely produce color errors in strong
highlights of natural subjects.
Low Light. The Canon EOS Rebel T4i performed well on the low-light test, capturing bright images at the lowest light level (1/16 foot-candle), even with the lowest sensitivity setting (ISO 100). As expected, noise increases as ISO goes up and light levels go down, but noise remains fairly low up to ISO 1,600, and performance is still quite good up to ISO 6,400. Noise is a little high at ISOs 12,800 and 25,600, particularly when noise reduction is minimized (extreme right column in the table above).
Color balance was pretty neutral with Canon Rebel T4i's Auto white balance setting (just a touch cool), even at high ISOs, though at lower light levels white balance took on a slightly red or magenta tint. We didn't spot any issues with hot pixels, and only some very faint horizontal banding can be seen in darker areas at very high ISOs, but that's not unusual and shouldn't be a problem for properly exposed subjects.
The Canon T4i's new Multi Shot Noise Reduction modes takes a burst of four images and blends them together to average out noise. It really makes a difference at higher ISOs, making very high ISOs like 12,800 and 25,600 much more usable. As expected, it makes little difference at low to moderate ISOs, where noise is already low. Compare rows in the table above.
When using the optical viewfinder and phase-detect AF, the Canon Rebel T4i's autofocus system was able to focus on the subject down to just below the 1/8 foot-candle light level unassisted with our Sigma f/2.8 lens, and in complete darkness with AF assist enabled. In Live View mode using Hybrid AF, the Canon T4i was able to focus down to just below the 1/2 foot-candle light level, which is poor for an SLR with an f/2.8 lens.
As always, keep in mind that the longer shutter speeds here demand the use of a tripod to prevent any blurring from camera movement. (A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)
How bright is this? The one foot-candle light level that this test begins at roughly corresponds to the brightness of typical city street-lighting at night. Cameras performing well at that level should be able to snap good-looking photos of street-lit scenes.
NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) Digital SLRs like the Canon T4i do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.
Very high resolution with strong overall detail, but somewhat high default contrast and unremarkable dynamic range. Highlight Tone Priority and contrast adjustment options do a great job of dealing with tough lighting. Very good low-light performance.
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| +0.3 EV | +0.7 EV | +1.0 EV |
The Canon EOS Rebel T4i produced moderately high contrast with some washed-out highlights and deep shadows under the deliberately harsh lighting of the test above. The mannequin's face was too dim at the +0.3 EV and +0.7 EV settings, so we preferred the image with +1.0 EV exposure compensation. This resulted in more clipped highlights in the shirt and flowers than we're used to seeing from an APS-C sensor lately, indicating only average dynamic range compared to the best of recent competitors. Shadow detail was however pretty good, though somewhat noisy. Bottom line: while dynamic range isn't bad, the Canon T4i struggled a bit with this difficult shot compared to recent state-of-the-art peers.
Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here. In actual shooting conditions, be sure to use fill flash in situations like the one shown here; it's better to shoot in open shade whenever possible.)
Contrast Adjustment
We really like it when a camera gives us the ability to adjust contrast and saturation to our liking. It's even better when those adjustments cover a useful range, in steps small enough to allow for precise tweaks. As was the case with its saturation adjustment, the Canon T4i's contrast setting meets both challenges very well.
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Minimum Contrast
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| Contrast set to lowest, +0.7 EV |
Contrast set to lowest, 0 EV |
| Contrast Adjustment Examples | ||||
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| -4 | -2 | 0 | +2 | +4 |
Highlight Tone Priority
The Canon EOS Rebel T4i's Highlight Tone Priority (HTP) option did an excellent job of preserving highlight detail, as shown below. (Mouse over the Off and On links to load the corresponding thumbnail, histogram and crops.)
Both shots above were captured at the same exposure, the only difference being that HTP was enabled for the second shot which necessarily increases the ISO to 200; part of how HTP works. The result is evident in the histograms and thumbnails above, clearly showing the superior highlight preservation when HTP is enabled, while shadow brightness is left relatively untouched. If you look closely at shadows however, you'll notice an increase in noise is the price you pay when ISO is boosted from 100 to 200. Except in the very deepest shadows, though, overall noise is low enough at ISO 200 that this is really a negligible trade-off for all but the most critical applications.
Automatic Lighting Optimization
Like the 60D, T2i and T3i, the Canon Rebel T4i offers three selectable levels of Automatic Lighting Optimization (ALO), plus Off. In fully automatic and Creative Auto exposure modes, ALO is automatically enabled. All four shots below were taken with the same default exposure settings. Mouse over the links below to load the associated thumbnail and histogram, and click on the links to load full resolution images.
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Automatic Lighting Optimization
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Face Detection
Just like most point & shoot cameras these days, the Canon EOS Rebel T4i has the ability to detect faces in Live View mode, and adjust exposure and focus accordingly.
| Face Detection | ||
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| Aperture Priority Face Detect: Off 0 EV |
Aperture Priority Face Detect: On 0 EV |
Auto Mode 0 EV |
Dynamic Range
A key parameter in a digital camera is its Dynamic Range, the range of brightness that can be faithfully recorded. At the upper end of the tonal scale, dynamic range is dictated by the point at which the RGB data "saturates" at values of 255, 255, 255. At the lower end of the tonal scale, dynamic range is determined by the point at which there ceases to be any useful difference between adjacent tonal steps. Note the use of the qualifier "useful" in there: While it's tempting to evaluate dynamic range as the maximum number of tonal steps that can be discerned at all, that measure of dynamic range has very little relevance to real-world photography. What we care about as photographers is how much detail we can pull out of the shadows before image noise becomes too objectionable. This, of course, is a very subjective matter, and will vary with the application and even the subject matter in question. (Noise will be much more visible in subjects with large areas of flat tints and subtle shading than it would in subjects with strong, highly contrasting surface texture.)
What makes most sense then, is to specify useful dynamic range in terms of the point at which image noise reaches some agreed-upon threshold. To this end, Imatest computes a number of different dynamic range measurements, based on a variety of image noise thresholds. The noise thresholds are specified in terms of f-stops of equivalent luminance variation in the final image file, and dynamic range is computed for noise thresholds of 1.0 (low image quality), 0.5 (medium image quality), 0.25 (medium-high image quality) and 0.1 (high image quality). For most photographers and most applications, the noise thresholds of 0.5 and 0.25 f-stops are probably the most relevant to the production of acceptable-quality finished images, but many noise-sensitive shooters will insist on the 0.1 f-stop limit for their most critical work.
JPEG.
The graph at right (click for a larger version) was generated using
Imatest's dynamic range analysis for an in-camera Canon Rebel T4i JPEG
file with a nominally-exposed density step target (Stouffer 4110). At
default camera settings and base ISO, the graph shows 11.1 f-stops of
total dynamic range, with 7.41 f-stops at the "High" Quality level.
These are decent numbers for a JPEG, though somewhat lower than some
recent competitors. Compared to the Canon T3i which uses a similar
sensor with an older processor, the T4i scored slightly higher at the
High Quality level (7.41 vs 7.31 f-stops), and significantly higher in
total dynamic range (11.1 vs 9.95 f-stops). Note though that this
measurement has a margin of error of about 1/3 f-stop, so differences of
less than 0.33 can be ignored.
Raw. The
graph at right is from the same Stouffer 4110 stepchart image captured
as a raw (.CR2) file, processed with Adobe Camera Raw using the Auto
setting. The Canon T4i's raw file scored 0.8 f-stop more in total
dynamic range (11.9 vs 11.1 f-stops) but the score at the highest
quality level increased only 0.15 f-stops from 7.41 to 7.56, which is an
insignificant improvement and below average these days. Results are
very similar to those of the Canon T3i at the High Quality level (7.56
vs 7.63 f-stops), though the total dynamic range score was higher like
the JPEG, at 11.9 vs 11.1 f-stops. Like all recent Canon SLRs, these
scores are somewhat below average for a modern APS-C sensor. As always,
it's worth noting here is that ACR's default noise reduction settings
reduced overall noise somewhat (see the plot in the lower left-hand
corner) relative to the levels in the in-camera JPEG, which would tend
to boost the dynamic range numbers for the High Quality threshold, but
notice that pixel noise in darker midtones and shadows is actually
higher than the JPEG. Also, the extreme highlight recovery being
performed by ACR here would likely produce color errors in strong
highlights of natural subjects.| 1 fc 11 lux |
1/2 fc 5.5 lux |
1/4 fc 2.7 lux |
1/8 fc 1.3 lux |
1/16 fc 0.67 lux |
1/16fc No NR |
|
|---|---|---|---|---|---|---|
| ISO 100 |
 2 s f2.8 |
 4 s f2.8 |
 8 s f2.8 |
 16 s f2.8 |
 32 s f2.8 |
 32 s f2.8 |
| ISO 200 |
 1 s f2.8 |
 2 s f2.8 |
 4 s f2.8 |
 8 s f2.8 |
 16 s f2.8 |
 16 s f2.8 |
| ISO 400 |
 0.5 s f2.8 |
 1 s f2.8 |
 2 s f2.8 |
 4 s f2.8 |
 8 s f2.8 |
 8 s f2.8 |
| ISO 800 |
 1/4 s f2.8 |
 0.5 s f2.8 |
 1 s f2.8 |
 2 s f2.8 |
 4 s f2.8 |
 4 s f2.8 |
| ISO 1600 |
 1/8 s f2.8 |
 1/4 s f2.8 |
 0.5 s f2.8 |
 1 s f2.8 |
 2 s f2.8 |
 2 s f2.8 |
| ISO 3200 |
 1/16 s f2.8 |
 1/8 s f2.8 |
 1/4 s f2.8 |
 0.5 s f2.8 |
 1 s f2.8 |
 1 s f2.8 |
| ISO 6400 |
 1/32 s f2.8 |
 1/16 s f2.8 |
 1/8 s f2.8 |
 1/4 s f2.8 |
 0.5 s f2.8 |
 0.5 s f2.8 |
| ISO 12800 |
 1/64 s f2.8 |
 1/32 s f2.8 |
 1/16 s f2.8 |
 1/8 s f2.8 |
 1/4 s f2.8 |
 1/4 s f2.8 |
| ISO 25600 |
 1/128 s f2.8 |
 1/64 s f2.8 |
 1/32 s f2.8 |
 1/16 s f2.8 |
 1/8 s f2.8 |
 1/8 s f2.8 |
Low Light. The Canon EOS Rebel T4i performed well on the low-light test, capturing bright images at the lowest light level (1/16 foot-candle), even with the lowest sensitivity setting (ISO 100). As expected, noise increases as ISO goes up and light levels go down, but noise remains fairly low up to ISO 1,600, and performance is still quite good up to ISO 6,400. Noise is a little high at ISOs 12,800 and 25,600, particularly when noise reduction is minimized (extreme right column in the table above).
Color balance was pretty neutral with Canon Rebel T4i's Auto white balance setting (just a touch cool), even at high ISOs, though at lower light levels white balance took on a slightly red or magenta tint. We didn't spot any issues with hot pixels, and only some very faint horizontal banding can be seen in darker areas at very high ISOs, but that's not unusual and shouldn't be a problem for properly exposed subjects.
| 1 fc 11 lux |
ISO 100 |
ISO 200 |
ISO 400 |
ISO 800 |
ISO 1600 |
ISO 3200 |
ISO 6400 |
ISO 12800 |
ISO 25600 |
|---|---|---|---|---|---|---|---|---|---|
|
Std.
NR |
2 s f2.8 |
1 s f2.8 |
0.5 s f2.8 |
1/4 s f2.8 |
1/8 s f2.8 |
1/16 s f2.8 |
1/32 s f2.8 |
1/64 s f2.8 |
1/128 s f2.8 |
|
Multi
Shot NR |
 2 s f2.8 |
 1 s f2.8 |
 0.5 s f2.8 |
 1/4 s f2.8 |
 1/8 s f2.8 |
 1/16 s f2.8 |
 1/32 s f2.8 |
 1/64 s f2.8 |
 1/128 s f2.8 |
The Canon T4i's new Multi Shot Noise Reduction modes takes a burst of four images and blends them together to average out noise. It really makes a difference at higher ISOs, making very high ISOs like 12,800 and 25,600 much more usable. As expected, it makes little difference at low to moderate ISOs, where noise is already low. Compare rows in the table above.
When using the optical viewfinder and phase-detect AF, the Canon Rebel T4i's autofocus system was able to focus on the subject down to just below the 1/8 foot-candle light level unassisted with our Sigma f/2.8 lens, and in complete darkness with AF assist enabled. In Live View mode using Hybrid AF, the Canon T4i was able to focus down to just below the 1/2 foot-candle light level, which is poor for an SLR with an f/2.8 lens.
As always, keep in mind that the longer shutter speeds here demand the use of a tripod to prevent any blurring from camera movement. (A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)
How bright is this? The one foot-candle light level that this test begins at roughly corresponds to the brightness of typical city street-lighting at night. Cameras performing well at that level should be able to snap good-looking photos of street-lit scenes.
NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) Digital SLRs like the Canon T4i do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.
OUTPUT QUALITY
Print Quality
Good 20 x 30-inch prints at ISO 100; ISO 3,200 shots are better at 13 x 19; and ISO 25,600 images make a quality 4 x 6!
ISO 100 shots are good at 24 x 36, but just soft enough that I prefer the 20 x 30-inch shots.
ISO 200 images look great at 20 x 30.
ISO 400 files are almost identical to ISO 200, also great at 20 x 30.
ISO 800 shots are a little softer at 20 x 30, but still quite good.
ISO 1,600 shots are better at 16 x 20. Noise suppression has started to affect reds, and some luminance noise haunts the shadows.
ISO 3,200 shots are a bit too soft for 16 x 20, but are good at 13 x 19 inches.
ISO 6,400 images are a bit rough at 11 x 14, but quite good at 8 x 10.
ISO 12,800 images are usable at 8 x 10, but very nice at 5 x 7.
ISO 25,600 files are good but a bit grainy at 5 x 7, but tighten up nicely at 4 x 6.
Overall, pretty impressive performance, about on par with the Canon T3i.
Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon Pro9000 Mark II studio printer, and on the Canon Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)
Good 20 x 30-inch prints at ISO 100; ISO 3,200 shots are better at 13 x 19; and ISO 25,600 images make a quality 4 x 6!
ISO 100 shots are good at 24 x 36, but just soft enough that I prefer the 20 x 30-inch shots.ISO 200 images look great at 20 x 30.
ISO 400 files are almost identical to ISO 200, also great at 20 x 30.
ISO 800 shots are a little softer at 20 x 30, but still quite good.
ISO 1,600 shots are better at 16 x 20. Noise suppression has started to affect reds, and some luminance noise haunts the shadows.
ISO 3,200 shots are a bit too soft for 16 x 20, but are good at 13 x 19 inches.
ISO 6,400 images are a bit rough at 11 x 14, but quite good at 8 x 10.
ISO 12,800 images are usable at 8 x 10, but very nice at 5 x 7.
ISO 25,600 files are good but a bit grainy at 5 x 7, but tighten up nicely at 4 x 6.
Overall, pretty impressive performance, about on par with the Canon T3i.
Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon Pro9000 Mark II studio printer, and on the Canon Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Canon EOS Rebel T4i (EOS 650D) Photo Gallery.
source : imaging-resource.com
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