Canon T7i Tech Info
Canon T7i Review -- Technical Info
by Mike Tomkins
The Canon Rebel T7i is based around a 24.2-megapixel APS-C CMOS image sensor, the same resolution as used in the previous-generation camera. The image sensor is overlaid with a low-pass filter that subtly blurs the finest details to help fight moir and false-color effects, a sensible choice in a camera aimed at consumers. Total resolution of the 22.3 x 14.9mm sensor is 25.8 megapixels, and it has a 3:2 aspect ratio. The pixel pitch is approximately 3.72µm, and an RGB Bayer color filter is used.
Output from the Canon T7i's image sensor is handled by the company's current-generation DIGIC 7 image processor.
Together, this pairing of sensor and processor are able to provide a wide sensitivity range encompassing everything from a minimum of ISO 100-equivalent to a maximum of ISO 25,600-equivalent by default, with the ability to expand this range to a maximum of ISO 51,200-equivalent if image quality isn't your primary concern.
An auto sensitivity function is provided, and able to span the entire standard sensitivity range when shooting without flash in Program, Priority or Manual exposure modes. In most other modes, auto sensitivity is capped at a maximum of ISO 6400-equivalent.
At its fastest, the Canon T7i can capture some six frames per second with single-servo autofocus, meaning that focus is not being adjusted after the first frame has been captured. Enabling continuous autofocus reduces this rate to a maximum of 4.5 fps, while a low-speed continuous mode can shoot at 3.0 fps.
The buffer depth for JPEG images is essentially limited only by available card space and power, presuming you're shooting with a UHS-I compliant flash card. If you're a raw shooter, Canon predicts a UHS-I burst depth of 27 raw frames, while raw+JPEG shooters should be able to manage around 23 frames in a burst.
As in the company's other recent APS-C DSLR offerings, the Canon T7i features a Canon EF / EF-S compatible lens mount that can use either full-frame or sub-frame optics. Note, though, that (again as in other Canon DSLR models) the Rebel T7i cannot use EF-M lenses designed for Canon's mirrorless cameras.
For the second generation running, the Canon T7i has received a big upgrade in the autofocus department. (And that's true whether we're talking about shooting through the viewfinder, or in live view mode.)
Let's start with viewfinder-based shooting. Here, the Canon T7i relies on a dedicated phase detection autofocus sensor to provide a total of 45 autofocus points across much of the image frame, with all of them being cross-types that are sensitive to detail on both the horizontal and vertical axes. Of these, 27 points work to f/8 (although only nine of them on both axes), and the central point is a dual cross-type supporting either f/2.8 or f/5.6.
The dedicated PDAF sensor has a working range of -0.5 to 18 EV, while the centermost point can manage -1 to 18 EV at f/5.6, or -3 to 18 EV at f/2.8. Focus points can be selected automatically, manually, or grouped as either three or nine AF zones. Autofocus assist illumination is provided with intermittent firing of the T7i's built-in, popup flash strobe.
Returning to the live view mode, meanwhile, the Canon T7i uses Canon's Dual Pixel CMOS AF technology to focus using phase-detection autofocus pixels on the image sensor, a system which works with all EF and EF-S lenses to date. Contrast-detection autofocus isn't provided, but you can of course focus manually, with an optional 5x or 10x focus magnification function to help you get your chosen subject tack-sharp.
Like the T6i before it, the Canon T7i uses a 7,560 pixel RGB+IR metering sensor that's sensitive to red, green, blue and infrared light. This helps both with exposure metering of difficult subjects, and with determining the location of skin tones (and thereby, the locations of people, allowing the exposure to be tweaked for the most attractive results.)
Like most consumer DSLRs, the Canon T7i features a pentamirror optical viewfinder, as opposed to a brighter, heavier and more expensive pentaprism. Coverage is approximately 95%, which is again typical for consumer DSLRs, and magnification is about 0.82x, unchanged from the T6i.
Eyepoint is approximately 19mm (at -1m-1 from the eyepiece lens center) and there's a dioptric adjustment with a range of -3.0 to +1.0m-1. An LCD overlay in the viewfinder allows a generous range of information to be provided to you without the need to switch to the main LCD monitor, including AF points and AF area frames, spot metering circle, electronic level, grid, aspect ratio lines and flicker detection.
Unlike the viewfinder in the simultaneously-launched EOS 77D, that used in the Rebel T7i lacks a proximity sensor adjacent to the viewfinder eyepiece. That difference means you'll need to manually toggle the display mode using a dedicated button on the top deck to disable the LCD, if you want to prevent glare and improve battery life when shooting through the finder.
On the rear of the Canon T7i is a side-mounted, tilt/swivel LCD monitor similar to that of the earlier Rebel T6i. As in that camera, it's based around a 3.0-inch LCD panel with a total dot count of around 1.04 million dots, and is overlaid with a touchscreen that allows it to be used as an input device. Coverage is a manufacturer-claimed 95%, and the monitor features Canon's Clear View II coatings, which aim to prevent smudges but not reflections. A seven-step brightness control is provided to help improve indoor / outdoor visibility.
And thanks to the articulation mechanism, which allows viewing from a wide range of angles, it's both selfie-friendly (assuming you're using an appropriate lens, of course), and can be closed inwards for a modicum of protection against smudges or minor bumps and scrapes.
The Canon T7i lacks the secondary, monochrome LCD panel of the EOS 77D, which sits on the top deck and provides a quick at-a-glance indication of basic camera settings.
To help throw a little more light on nearby subjects, the Canon T7i includes a built-in, popup flash that sits in the traditional position above the viewfinder pentamirror housing. The built-in flash has a guide number of 12 meters at ISO 100, and it can also be used as a master in an optical wireless flash setup.
Of course, there's also a flash hot shoe on the top deck for use with external strobes. E-TTL II flash metering is used, and +/-2 EV of flash exposure compensation is available in 1/3 or 1/2 EV steps.
The Canon Rebel T7i offers all of the usual creative options, just as you'd expect from a DSLR camera.
You can, of course, opt for Program (with Program Shift), Aperture-priority, Shutter-priority or fully Manual exposure modes. There's also a choice of Scene Intelligent Auto or Creative Auto modes, a Flash Off mode, plus a choice of four Scene modes with their own positions on the Mode dial: Portrait, Landscape, Close-up and Sports. In addition, there's a Scene position which provides access to a further seven scene modes, plus a Creative Filters position which offers up a total of ten filter types.
Canon's Picture Style function, meanwhile, provides for seven preset picture styles, plus both an auto style selection function and three user-defined styles. A total of eight white balance modes are provided, including auto (with ambience or white-priority controls), custom and six presets. Color temperature can also be tweaked within +/- nine steps on the blue/amber and magenta/green axes.
The Rebel T7i provides the ability to record high-definition movies at up to Full HD (1,920 x 1,080 pixels) resolution with a rate of up to 60 frames per second, double the 30p maximum of the T6i. 30p and 24p rates are also available at Full HD, but not the 25p rate which was available in the earlier camera. At HD resolution (1,280 x 720 pixels), a choice of 30p or 60p rates is offered, while VGA (640 x 480) mode is now fixed at 30 fps.
Recording time per clip is limited to 29 minutes and 59 seconds. The maximum movie file size is 4GB unless you're using an exFAT file system, but the T7i will automatically create subsequent files without interruption up to the aforementioned time limit.
Like the Canon T6s before it, the Canon T7i can also shoot high dynamic range movies, a feature that will likely pay dividends in difficult lighting situations. It can also shoot time-lapse movies, a new addition since the Rebel T6s and T6i.
Audio comes courtesy of a built-in stereo microphone, or via a 3.5mm microphone jack which can be found beneath an access panel on the left side of the camera's body. Movies are recorded using MPEG-4 AVC / H.264 compression with a variable bit-rate, an MP4 container and AAC stereo audio.
The Canon T6s brought in-camera Wi-Fi and NFC to the flagship Rebel camera, and now the Canon T7i adds Bluetooth into the mix. And not only can this all be used to get your photos onto your smartphone or tablet -- and from there, to social networks -- just as quickly as possible, but the Bluetooth radio in particular can be used with a new BR-E1 Bluetooth wireless remote control. This has a range of 16 feet, and does not require line-of-sight access to the camera body, potentially making it more useful in certain situations.
Wired connectivity in the Canon T7i includes a USB 2.0 High Speed data port and a Type-C HDMI high-definition video output. Unlike the earlier T6i, there's no longer any support for standard-definition displays.
A second flap covers a wired remote jack and a 3.5mm stereo microphone jack, but there's no headphone jack. Of course the Rebel T7i includes a dedicated hot shoe for external flash units and other shoe-mount accessories.
Images and movies are stored on Secure Digital cards, courtesy of a single SD card slot that is compatible with SDHC, SDXC and UHS-I cards. The Canon T7i also supports Eye-Fi cards, although given the in-camera Wi-Fi connectivity, there would seem to be little reason to use one.
Still images can be stored in raw or JPEG formats, or both simultaneously. Movies are stored in MP4 format, using an MPEG-4 AV/H.264 codec for video compression, and AAC stereo for audio.
Power comes courtesy of a proprietary LP-E17 lithium-ion battery pack, the same model used earlier in the T6i. Battery life is now rated at 600 shots on a charge when using the optical viewfinder or 270 shots in live view mode, both figures having been recorded at 73°F and with 50% flash usage. That's a healthy step upwards from the 440 and 180 shots on a charge, respectively, for the T6i and T6s in viewfinder and live view shooting.