The Canon T3i is Canon's "top of the line" model in their entry level Rebel series of DSLRs. The major new feature is a tilt and swivel foldout LCD screen. Otherwise it's somewhat of an incremental software update of the Canon EOS T2i, incorporating features from the T2i, the EOS 60D and the EOS 7D (Canon's top-of-the-line crop sensor DSLR) and adding a few new ones.
I had the chance to shoot with the Canon T3i for a couple of days and the following comments are based on my experience with the camera.
In some ways it's an easy camera to review because the T2i, T3i, EOS 60D and EOS 7D all use essentially the same 18 MP sensor (the 7D has a faster readout system), which means that for all intents and purposes the basic image quality is the same for all four cameras. The resolution, dynamic range and noise are pretty much the same whichever camera you choose. The cameras differ in features, and that's where the choice lies. The Canon EOS 60D and Canon EOS 7D have a better AF system, a faster shooting rate, a larger buffer, a rear Quick Control Dial (QCD) and more bells and whistles (especially the EOS 7D). However those features come at the cost of a larger size and a higher price.
Or "what do you get for the extra $100-$150"?
The T3i uses a very similar user interface to the other digital Rebel series DSLRs. The main control dial on the top of the camera selects shooting mode, a 4 way controller on the rear of the camera allows menu navigation and a series of buttons select functions such as ISO. metering mode, drive mode etc. One new button appears on the T3i for display control. On the T2i there is s sensor which detects when the camera is held up to the user's eye and switches off the rear LCD display (no point in consuming power when you can't see the LCD). The swing out and swivel LCD of the T3i doesn't have this feature (lack of space due to the swing out LCD?) and instead the "DISP" button turns the LCD display on and off.
The T3i, like the other Digital Rebel series cameras, lacks a top LCD display and it doesn't have a rear QCD (quick control dial). The rear LCD is used for all information display. In practice this isn't a big disadvantage most of the time and it does mean that the camera can be made smaller. The QCD of the 60D and 7D enable easier and more rapid changing of some functions, such as exposure compensation. However the same functions are available on the T3i, it's just that they require an extra button push and so take a little longer and are less convenient. It's ergonomics. The rear QCD just makes the camera a little easier to use.
The T3i now has a feature which displays "hints" for the novice user. For example if you select aperture priority (Av) mode, a message is displayed on the LCD which says "Adjust aperture to blur background (subjects stand out) or keep foreground and background in focus". I don't think it's particularly helpful for novices since it doesn't say how to adjust to blur background (make aperture larger by setting lower f-stop numbers), but some of the messages might be useful. For those who don't want the "training wheels" on their camera, the messages can be turned off via a menu function.
The T3i uses a pentamirror rather than a pentaprism. A pentamirror is a system of mirrors while a pentaprism is made of solid glass. In theory a pentamirror doesn't give as bright an image as a pentaprism and to compensate, the image is often made a little smaller. The smaller image isn't really noticeable unless you compare the T3i side by side with a 60D or 7D and you quickly get used to it.
The viewfinder displays the usual shooting information foound on other EOS DSLRs including ISO setting, aperture and shutter speed, exposure compensation, focus zones, spot metering zone, HTP, FEC etc
Viewfinder coverage is 95% (horizontal and vertical) of the actual recorded frame size and the magnification is 0.85x
The image quality of the T3i is easy to describe. For all intents and purposes it's exactly the same as that of the T2i, EOS 60D and EOS 7D, which is to say very good. All four cameras use the same 18MP sensor, all show the same level of noise, all show the same dynamic range and all have the same resolution. All four hav ethe same ISO range, from 100 to 12,800 (expanded). In a sense we're almost back to the situation we had before the digital era. All 35mm cameras had the same intrinsic image quality since that was determined by the film and all 35mm cameras used the same film. With the T2i, T3i, 60d and 7D series, all the cameras have what amounts to the same "film".
Differences in image quality between the T2i, T3i, 60D and 7D depends on only two factors, the quality of the lens used and the skill of the photographer in selecting the optimum settings for such factors as ISO, white balance, exposure etc.
The AF system of the T3i is the same as that of the T2i. There are 9 AF zones with the center zone having cross sensitivity and extra accuracy for lenses f2.8 or faster. The outer zones are linear sensors.
AF is fine for most subjects. It's fast and accurate but for moving subjects the 60D offers better performance with 9 cross type sensors and the 7D even better performance with 19 cross type sensors and variable sensor configurations. The EOS 7D would be the crop sensor EOS body of choice if you want to capture fast action sports or birds in flight, but for normal subjects the AF system of the T3i works well in most situations.
In live view there's a choice between phase detection and contrast detection AF. Phase detection is optically based, is fast and accurate and is the system used in normal reflex mode. However it requires that the mirror drop down while AF is operating and that interrupts the live view. Contrast detection does not interrupt the live view since it looks at the image on the sensor, but is slow. It would not be unusual for focusing to take several seconds in contrast detection mode. Both modes make it difficult to focus on a moving subject.
The T3i can shoot at up to 3.7 frames/sec. The use of a fast SD card is recommended for maximum performance. If you're shooting JPEGs, with an average subject the buffer fills after about 35 frames, at which point the frame rate drops to somewhere around 2.5fps. If you're shooting RAW images you only get around 6 frames before the shooting rate drops to less than 1 frame/second. If you want to simultaneously store images in both JPEG and RAW formats it only takes about three frames to fill the buffer at which point the rate drops to around a frame every two seconds.
In JPEG mode most users are not likely to have problems as it's pretty rare than you'd want to shoot more than 35 frames (continuous shooting for about 10 seconds). However in RAW mode - and even more so in RAW+JPEG mode - the small buffer could become an issue for action shooters since you only get 1 or 2 seconds before the buffer fills and the shooting rate drops dramatically. If you want to quickly shoot multiple images in RAW mode, an EOS 60D - or better an EOS 7D - would enable you to do that more easily.
The T3i has two features which make it perhaps the best featured Canon DLSR for shooting video. The first is the high resolution ant-glare coated foldout, tilt and swivel LCD screen which can be positioned for optimal viewing while shooting at eye level, waist level, ground level, overhead or even around corners. If you shoot a lot of video you'll soon find that this is much more convenient than using a fixed LCD screen on the back of the camera. It's actually quite useful for still photography too under difficult circumstances (such as low level shooting).
The second video related feature is that the audio level can be manually set (there is also an auto setting). In manual mode the microphone gain isn't turned all the way up when there is little or no sound to record, which lowers background noise.
Exposure can be controlled manually or automatically. Like all the other EOS DSLR cameras, there is no automatic focus tracking in video mode. Refocusing is possible using either contrast detection (which doesn't interrupt the video) or phase detection (which requires a break in the video while the reflex mirror drops and focus is reset). Phase detection is fast and accurate, contrast detection is slow and may "hunt" for focus. Manual focus is still the best way to change focus in video mode with any EOS DSLR shooting video.
While the 5D MkII has manual audio settings and the EOS 60D has the tilt and swivel screen, the EOS T3i is the first (but certainly not last) Canon EOS DSLR to incorporate both features.
The T3i can record 1080p HD video (1920x1080) at 30, 25 or 24fps, 720p (1280x720) HD video at 50 or 60 fps and VGA (640x480) video at 50 or 60 fps. Movies are saved in quicktime (.mov) format with linear PCM audio and video clips are limited to 30m or a maximum file of 4GB (whichever comes first). The file size limit is due to the operating system, not a camera limitation. The use of a fast SD card (at least class 6) is recommended, and in fact is required for shooting continuous 1080p HD video. Class 10 cards are now reasonably cheap and widely available.
In addition to these "full sensor modes", there's a zoom feature which operates by using only the center portion of the sensor. Canon claim that "Full HD quality" is maintained over a range from 3x to 10x. Well, maybe. Canon don't specify exactly how they are getting the 10x magnification. You can get a true 3x "zoom" (actually 2.7x) by simply using only the center 1920 x 1080 pixels from the full 5184 x 3456 frame. In that case there would be no quality loss when compared to 1080P video shot without zoom since that uses the full frame and downsizes it (or only reads out a subset of pixels). More magnification than 2.7x would seem to require "digital zoom", which is basically upsizing the image and interpolating pixels. There will inevitably be some quality loss, so whether "Full HD quality" is maintained is a judgment call and may depend on how the resulting video is viewed. 10x is probably something like 2.7x true (cropping) zoom plus 3.7x digital zoom (resampling). If the 10x were done via digital cropping rather than interpolation, the maximum image size at full resolution would only be 518 x 346 pixels.
At 10x zoom with a long lens there may be image stability problems unless the camera is mounted on a solid tripod. Even with IS you're not going to be able to hold the camera steady at an effective 4800mm focal length (300mm lens plus 1.6x crop factor plus 10x zoom).
The T3i also has a Video Snapshot feature which permits the user to record a series of two, four or eight second clips. The clips are then assembled in the camera into a continuous video and can be further edited in-camera or through Canon's Video Snapshot Task software on a PC.
The T3i is available as a kit with the Canon EF-S 18-55 IS and it's a pretty good deal since the price is usually less than $100 more than the body alone. It's not a great lens, but it's quite usable and very small and light with effective image stabilization. The 55mm maximum focal length limits its use for sports and wildlife, but it's a decent general purpose lens for travel and portraits
A slightly better lens might be the Canon EF-S 18-135/3.5-5.6. It cover a significantly larger range then the 18-55 and the 135mm focal length (equivalent in coverage to a 216mm lens on a full frame camera) makes it more useful for things like sports and wildlife. Again the IS system is very effective. A T3i/18-135 kit is available and it's around $100 cheaper that way than buying the body and lens separately.
If you want one lens to do everything, the Tamron 18-270/3.5-6.3 PZD might be the best bet. It has a very wide zoom range, effective image stabilization and it's very small for a lens with such a long zoom range.
The Canon Digital Rebel T3i is the logical development of Canon's current DSLR philosophy which differentiates cameras by features rather than by image quality. In the current EOS DSLR lineup the Rebel T2i, Rebel T3i, EOS 60D and EOS 7D all use the same 18MP sensor and they all have essentially identical image quality. The Canon EOS Rebel T3i is the top-of-the-line entry level camera. It actually has better video capability than any of the other cameras since it incorporates the tilt and swivel LCD of the 60D and adds full manual control over audio levels. The cost is kept down below that of the Canon EOS 60D by the use of a simpler AF system, a pentamirror rather than a pentaprism, not top mounted LCD display, no rear QCD, extensive use of plastics in construction and a reduced feature set. However none of these affect image quality, just convenience. The T3i is clearly aimed at the novice user, with "assist" screens available for most functions, but it's also a very capable camera in the hands of more experienced users and the "helper' messages can be turned off and almost all the camera defaults can be manually overridden.
The T3i would be a good buy for the novice user who wants a camera that they can "grow into" with time and which can compete with more expensive cameras in terms of image quality. It makes an excellent backup camera for Canon photographers with more advanced DSLRS since its small size and light weight make it easy to carry. Those features also make it an ideal camera for travel, especially when combined with a small wide-to-tele zoom.
So if you 're looking for a starter camera, but one that will deliver the highest image quality at the lowest cost, the Canon T3i (600D) probably delivers the best bang for the buck in the Canon EOS lineup. It's an excellent camera, user friendly and capable of yielding very high quality still images and very good 1080p HD video.