An illustrated chronological story about how Canon autofocus systems and viewfinders went from a single AF point (1987) to 191 AF points (2020).
Since the introduction of their EOS series of cameras in 1987, Canon has developed 20 phase detection autofocus systems, resulting in 20 different autofocus sensor designs. This article is a completely unique graphical review of all the phase detection autofocus sensors Canon has ever used. An overview like this one has never been done before at this level of detail.
Canon had already developed zoom lenses and cameras with autofocus capabilities even years before the first EOS camera had been invented. The Canon Zoom Lens FD 35-70mm 1:4 AF was a lens that had an independent rangefinding system integrated. It was introduced in 1981 and was compatible with all Canon FD mount cameras. Four years later in 1985, Canon introduced their T80 SLR camera. It was Canon's first 35mm film SLR camera that offered an in-body autofocus system. All these systems introduced prior to Canon's EOS series of SLR and DSLR cameras are not in scope of this article. Instead, the following chapters cover 20 different autofocus sensor designs from the introduction of Canon's EOS system (1987) to the last EOS camera using phase detection autofocus (2020).
In contrast to manual focus, autofocus allows photographers to focus the camera on a subject automatically. It is one of the most convenient features in photography and it is absolutely crucial for capturing sharp and clear images, especially in dynamic situations. All of Canon's EOS cameras display AF points in their viewfinders. These mark the positions at which the camera is able to focus the lens at a subject automatically.
This article covers Canon's autofocus (AF) systems that used phase detection (PD) technology in order to determine the correct focusing position of the photographic lens. This technology is also described as through-the-tens (TTL) secondary image registration (SIR) phase detection autofocus. Read more about the underlying principle of phase detection autofocus here.
Phase detection systems use sets of small detector stripes that are arranged on the types of autofocus chips shown in this article. One set of detector lines refers to all physical line detectors on the chip that correspond to one AF point in the camera's viewfinder. Depending on the type of AF detector, one set can be two detector stripes (linear sensor), four detector stripes (cross-type sensor), or eight detector stripes (dual cross-type sensor). Note that multiple adjacent AF points often use the same set of detectors.
The autofocus working range (light intensities at which an AF system can be used) is usually expressed as two exposure values (EV), for example EV 0 - 20. EV units are stops. The low value expresses that the camera can detect autofocus in scenes as dark as EV 0 and as bright as EV 20. Comparing two systems 1) EV 0 - 20 and 2) EV -1 - 21, the second system can still operate in much darker (half as bright) and also much brighter (double as bright) scenes than the first one.
The EOS 650 was the world's first EOS camera. For that reason, this single-point AF system was the first autofocus system ever used on Canon's EOS platform of DSLR cameras. It was the beginning of a race to increase phase detection autofocus performance for more than 30 years.
Both the Canon EOS 650 and the EOS 620 had a viewfinder that displayed one AF frame in the center of the focusing screen. The viewfinder also displayed a partial metering circle.
Canon named this innovative sensing device the BASIS (Base-Stored Image Sensor) chip. The BASIS chip consisted of support structures, leadframes, and the active sensor area embedded inside a clear-molded 14.0 mm × 8.2 mm package. This sensor had one set of horizontal detectors: The two black stripes were the actual light sensitive parts. The resolution of each stripe can be described as 47-bit, indicating that each detector line consisted of 47 tiny photoreceptor cells arranged next to each other. Some of the active area surrounding the detector lines was used for signal amplification and processing. The amplification circuitry allowed to use autofocus even in low light situations.
Due to the horizontal detector orientation, the AF point was sensitive to vertical contrast lines only. The detector used light that passed through the f/5.6 zone of the photo-taking lens. Therefore, autofocus was possible if the used lens offered a maximum aperture of f/5.6 or faster. Consequently, AF was not possible if the used lens was slower than f/5.6.
The system had an AF working range of EV 1 - 18 at ISO 100.
While this system still relied on a single AF point, the underlying AF sensor was more advanced. In addition to the pair of horizontal detectors (H-BASIS), this new system added a pair of vertical detectors (V-BASIS).
The Canon EOS 1 had a viewfinder that displayed one AF frame in the center of the focusing screen. The viewfinder also displayed a partial metering circle and a spot metering circle.
The overall sensor design was very similar to the previous one, where a clear 15.0 mm × 8.2 mm package was molded around the inner structures. This AF sensor was mounted to the phase detection unit in a vertical orientation.
One pair of vertical detectors was added to the device, creating the CT-BASIS (Cross-Type Base-Stored Image Sensor) chip. The two horizontal lines were 47-bit detector arrays and the two vertical ones were 29-bit detector arrays. The sensor pitch (distance between the individual photoreceptor cells) was 10% finer compared to the previous BASIS sensor.
Another innovation was the integration of two fine spot metering sensors (silicon photo cells) into the chip. This allowed the camera to perform very precise light readings around the center AF point. Another improvement was made by applying an antireflective film to the active area of the sensor. This prevented stray light from degrading the AF signal.
The cross-type sensor was sensitive to both vertical and horizontal contrast lines. The distance between vertical detectors was larger than that of horizontal detectors. This increased distance allowed high-precision autofocus detection on the vertical detector (sensitive to horizontal contrast lines). These high-precision vertical detectors required light from an outer area of the lenses exit pupil / aperture. For that reason, the vertical (high-precision, horizontal-sensitive) component of this sensor became active only when an f/2.8 or faster lens was attached to the camera. With lenses slower than f/2.8 but at least f/5.6, this autofocus system only offered standard-precision horizontal detectors (sensitive to vertical contrast lines). Autofocus was not possible with lenses slower than f/5.6.
The system had an AF working range of EV -1 - 18 at ISO 100.
This was the first Canon AF system with multiple AF positions. Canon called this new AF sensor design their Multi-BASIS technology. This new approach not only brought changes to the actual AF sensor but it also required a redesign of the optical assembly, adding two pairs of lenslets to the separator lens array and two additional mask openings. This new Multi-BASIS system offered lower working light capability and therefore provided faster, accurate focusing even in dim light.
Cameras using this 3-point AF system have a viewfinder that displays three AF frames in the center of the focusing screen. The viewfinder also displayed a partial metering circle.
This first Multi-BASIS chip was similar to previous BASIS chip designs. Package size was increased to 22.0 mm × 11.2 mm. The detector lines were arranged as shown in the illustration. The C-V-BASIS (center-vertical-BASIS) used two 42-bit and the C-H-BASIS (center-horizontal-BASIS) used two 32-bit detectors. Both L-V-BASIS and R-V-BASIS (left-vertical-BASIS and right-vertical-BASIS) each used two 38-bit detectors. Two additional pairs of separator lenses were used to cover these L-V and R-V detector lines.
The center AF point was a cross-type detector sensitive to vertical and horizontal contrast lines. Each of the outer AF points used a vertical pair of detectors sensitive to horizontal contrast lines. All sensors required a maximum aperture of f/5.6 to operate (standard-precision). There was no f/2.8 (high-precision) detector available.
The system had an AF working range of EV 0 - 18 at ISO 100.
The EOS D30 was the first Canon camera that used a CMOS (Complementary Metal Oxide Semiconductor) image sensor with a resolution of 3.1 megapixels. Read more about CMOS sensors here.
This system offered the same number and layout of AF points than the earlier 3-point AF system. However, this version was designed for APS-C format cameras.
Cameras using this 3-point AF system have a viewfinder that displays three AF frames in the center of the focusing screen. The viewfinder also displayed a partial metering circle.
This Multi-BASIS chip was similar to previous BASIS chip designs. Although housing multiple AF sensors, this chip was very compact by using the original 14.0 mm × 8.2 mm package that had also been used in the first single-point AF system. To achieve this, the left and right pairs of detectors have been brought closer towards the center. The C-V-BASIS used two 42-bit and the C-H-BASIS used two 32-bit detectors. The L-V-BASIS and R-V-BASIS used two 32-bit detectors each.
The center AF point was a cross-type detector sensitive to vertical and horizontal contrast lines. Each of the outer AF points used a vertical pair of detectors sensitive to horizontal contrast lines. All sensors required a maximum aperture of f/5.6 to operate (standard-precision). There was no f/2.8 (high-precision) detector available.
The system had an AF working range of EV 2 - 18 at ISO 100.
The system offered an increased number of AF points. With five AF points arranged horizontally across the viewfinder, this type of AF point coverage was also described with the term wide-zone focusing.
Each AF sensor was indicated with a small frame. The center was shaped as a uniform square whereas the remaining four AF sensors were rectangles, oriented with their long side vertically.
In principle, this sensor chip used the same design and structure as the previous Multi-BASIS sensors. Package size was 14.0 mm × 8.2 mm. The main difference, however, lied in the number of detectors. The C-V-BASIS (center-vertical-BASIS) used two 42-bit and the C-H-BASIS (center-horizontal-BASIS) used two 32-bit detectors. The two L-V-BASIS and two R-V-BASIS (left-vertical-BASIS and right-vertical-BASIS) all used pairs of 32-bit detectors.
The center AF point was a cross-type detector sensitive to vertical and horizontal contrast lines. Each of the outer AF points used a vertical pair of detectors sensitive to horizontal contrast lines. All sensors required a minimum aperture of f/5.6 to operate (standard-precision). There was no f/2.8 (high-precision) detector available.
The system had an AF working range of EV 0 - 18 at ISO 100.
This AF system combined the high-precision vertical detector (as already used in the Canon EOS 1) with the 5-point multi-AF-design (as already used in the Canon EOS 5). It was this combination why Canon called this the High-Precision Multi-BASIS sensor. In addition, this new AF system had incorporated a fine-spot metering sensor directly onto the AF chip. Further improvements have been made on the rangefinding circuitry inside the active area, which resulted in a significant reduction in processing time.
Each AF sensor was indicated with a small frame. The center is shaped as a uniform square whereas the remaining four AF sensors were displayed as rectangles, oriented with their long side vertically. The fine spot metering area was indicated as a small circle at the center of the viewfinder.
This AF chip used a similar 14.0 mm × 8.2 mm package than that of the EOS 5. The sensor array's layout resulted from the combination of various technologies that had already been used in previous AF systems:
Other adjustments had to be applied to the overall optical assembly including the separator lenses to match the array of detector lines. The integration of the fine-spot metering sensor into the chip resulted in a concentration of functionality, but also an addition of four pins. In order to keep the same size chip package as used in the EOS 5, a small adjustment to the pin size was required: The 0.8 mm pin pitch (EOS 5) was reduced to 0.65 mm (EOS 1N).
The center AF point worked in the same way as the AF point of the Canon EOS 1. The C-H-BASIS was designed for use with lenses having a maximum aperture of f/5.6 or faster (standard-precision) and was sensitive to vertical contrast lines. If a lens with a maximum aperture of f/2.8 or faster was attached to the camera, that center AF point became a cross-type sensor with the C-V-BASIS component being a high-precision detector. The other AF points (L-V-BASIS and R-V-BASIS) were vertical detectors, sensitive to horizontal contrast lines. These were designed for use with lenses having a maximum aperture of f/5.6 or faster (standard-precision). Autofocus was not possible with lenses slower than f/5.6.
The system had an AF working range of EV 0 - 18 at ISO 100.
Amplifiers can improve the signal-to-noise ratio (SNR) by increasing the signal strength relative to the noise floor. For that reason, each light receptor cell inside the detector strips was coupled with an own amplifier. In addition to these individual cell-amplifiers, another amplifier circuit with a gain factor of 20 was designed on-chip to further improve the system's sensitivity and SNR.
In automatic AF point selection mode, the camera's AF processor always carried out rangefinding calculations simultaneously for the H-BASIS and all V-BASIS detectors. This not only applied to the AF system of the Canon EOS 1N but practically to all autofocus systems with multiple sensors. The EOS-1N incorporated a dedicated AF processor with a clock speed of 12 MHz. While this clock speed was identical with the processor speed of the Canon EOS 1, the minimum AF calculation time was reduced from 33 µs (EOS 1) to 17 µs (EOS 1N) despite offering five times the number of AF points.
This was the first AF system that offered AF points above and below the center AF point. As it is used on APS-C cameras, viewfinder coverage is fairly large.
Each AF sensor is indicated with a small frame. The center is shaped as a uniform square whereas the remaining six AF sensors are rectangles, oriented depending on their sensitivity.
This was the first AF sensor that had a different chip package than the previous BASIS chips. For this new design, Canon embedded the active area inside a completely rectangular substrate and added transparent optical polymer on top. The active area accommodates eight detector pairs (black stripes in the illustration) as well as signal processing and amplifier circuitry surrounding the actual detectors.
All AF points are standard-precision sensors that are designed for use with lenses having a maximum aperture of f/5.6 or faster. The center point is a standard-precision cross-type (sensitive to both vertical and horizontal contrast lines). All other points are single line sensors. Their orientation is shown in the illustration. There are no f/2.8 high-precision sensors available. Autofocus is not possible during viewfinder shooting with lenses having maximum apertures slower than f/5.6.
The system has an AF working range of EV 0.5 - 18 at ISO 100.
The AF points are arranged on multiple levels, expanding towards left and right as well as upper and lower regions of the viewfinder. As it is used on APS-C cameras, viewfinder coverage is fairly large.
Each AF sensor is indicated with a small frame. The center is shaped as a uniform square whereas the remaining eight AF sensors are rectangles, oriented depending on their sensitivity.
The sensor chip package has a similar structure to the package of the 7-point chip. A rectangular substrate with the active area is covered in transparent optical polymer. This particular AF sensor has introduced two innovative features that affect the central focus point: Horizontally, the center AF point uses four detectors, one pair at a standard distance from each other and one pair further apart. Vertically, the center AF point uses two parallel pairs of detectors that are installed in a dual-line zig zag arrangement. The purpose of this configuration is that the photoreceptor cells of the two lines are offset by half a cell pitch, effectively doubling the detector resolution. This not only increases the accuracy at which the phase alignment can be detected by the AF system but also allows better defocus detection. All the other AF points use linear sensors.
The center AF point is an f/5.6 standard-precision cross-type sensor (sensitive to both vertical and horizontal contrast lines) and f/2.8 high-precision horizontal sensor (sensitive to vertical contrast lines). Six AF points are vertical sensors (sensitive to horizontal contrast lines) and two AF points are horizontal sensors (sensitive to vertical contrast lines) as shown in the illustration. Autofocus is not possible during viewfinder shooting with lenses having maximum apertures slower than f/5.6.
The system has an AF working range of EV -0.5 - 18 at ISO 100.
This was the first AF system that had invisible and non-selectable assist AF points integrated. These are active only during AI Servo mode and they allow the camera to predict the focus condition for moving subjects. As this 9-point AF system is used on full frame cameras, viewfinder coverage is not as large as seen on the other 9-point systems.
Each AF sensor is indicated with a small frame. The center is shaped as a uniform square whereas the remaining eight AF sensors are rectangles, oriented depending on their sensitivity. In addition, there is a small spot metering circle around the center AF point.
The sensor chip package has a similar structure to the package of the first 9-point chip. The AF sensor features additional sets of detectors that do not correspond to visible AF points but to invisible Assist AF points. Dual-line zig zag arrangements were used for both vertical and horizontal components of the center AF point. Additional sets of f/2.8 high precision detectors have been used for the horizontal part of the center AF point and for two Assist AF points.
The center AF point is an f/5.6 standard-precision cross-type sensor (sensitive to both vertical and horizontal contrast lines) and f/2.8 high-precision horizontal sensor (sensitive to vertical contrast lines). Six AF points are vertical sensors (sensitive to horizontal contrast lines) and two AF points are horizontal sensors (sensitive to vertical contrast lines) as shown in the illustration. The two horizontal Assist AF points (sensitive to vertical contrast lines) are f/5.6 standard-precision sensors but turn into f/2.8 high-precision sensors when an f/2.8 or faster lens is attached to the camera. The four vertical Assist AF points (sensitive to horizontal contrast lines) are f/5.6 standard-precision sensors. Autofocus is not possible during viewfinder shooting with lenses having maximum apertures slower than f/5.6.
The system has an AF working range of EV -0.5 - 18 at ISO 100.
This was the first of Canon's autofocus systems that had a dual cross-type autofocus detector installed. This dual cross-type sensor allows the camera to use high-precision focusing when an f/2.8 or faster lens is used. It was also the first AF system with multiple AF points all being cross-type sensors.
Each AF sensor is indicated with a small frame. In addition, there is a small spot metering circle around the center AF point.
The sensor chip package has a similar structure to the package of the previous 9-point chips. In order to enable cross-type capabilities to all AF points, this AF system uses an increased number of detector lines, particularly in the left and right zones. At the center, two pairs of dual-line zig zag detectors are placed vertically on the active area. These are jointly used by three AF points (the one on the top, at the center, and at the bottom). One new feature stands out: This sensor for the first time has a complete cross of high-precision detectors (✕-shape) that is arranged vertically around the center area of the active area.
All AF points function as standard-precision cross-type sensors (sensitive to both vertical and horizontal contrast lines) that are designed for use with lenses having a maximum aperture of f/5.6 or faster. The center point turns into a high-precision dual cross-type (sensitive to four contrast line orientations) with f/2.8 or faster lenses. Note that certain lenses may reduce some cross-type AF points to vertical-line or horizontal-line sensitive only (see the camera's instruction manual for details). Autofocus is not possible during viewfinder shooting with lenses having maximum apertures slower than f/5.6.
The system has an AF working range of EV -0.5 - 18 at ISO 100.
The number of AF points was increased, resulting in an 11-point AF system. One real innovation on this AF system was the increased low light sensitivity.
Each AF sensor is indicated with a small frame. The center is shaped as a uniform square whereas the remaining ten AF sensors are rectangles, oriented depending on their sensitivity. Again, note the smaller viewfinder coverage due to the full frame format of the camera.
The rectangular substrate is covered in transparent optical polymer just like previous sensors. While this is a new chip that has been redesigned (wire traces, bond wires, amplifier circuitry, etc.), the actual detector lines have an almost identical floorplan as the 9-point AF sensor used for the EOS 5D and EOS 5D Mark II. Interestingly, the 11-point AF sensor of the EOS 6D has various detector lines installed that could be used for up to eight Assist AF points arranged around the center AF point. However, there is apparently no documentation that the EOS 6D would actually use invisible auxiliary AF points. Rather, it can be assumed that the EOS 6D has such detectors on the hardware side, but that these are not used by the camera's firmware.
The center AF point is an f/5.6 standard-precision cross-type sensor (sensitive to both vertical and horizontal contrast lines) and f/2.8 high-precision horizontal sensor (sensitive to vertical contrast lines). Eight AF points are vertical sensors (sensitive to horizontal contrast lines) and two AF points are horizontal sensors (sensitive to vertical contrast lines) as shown in the illustration. Autofocus is not possible during viewfinder shooting with lenses having maximum apertures slower than f/5.6.
The system has an AF working range of EV -3 - 18 at ISO 100 at the center AF point and EV 0.5 - 18 at ISO 100 at all other AF points.
The number of AF points was increased, resulting in a 19-point AF system. This AF system soon earned a reputation of Canon's fastest and most reliable autofocus system available at that time.
Each AF sensor is indicated with two frames. AF points are divided into five zones, indicated by black frames. Viewfinder coverage is fairly large.
Pairs of detector lines on this sensor chip are laid out in a similar way to the 9-point AF system with the center dual cross-type sensor. However, this chip has an increased number of detectors in the center area. Further improvements have been made to the chip electronics (amplifiers, readout, etc.)
All AF points are standard-precision cross-type sensors designed for lenses having a maximum aperture of f/5.6 or faster. The center AF point turns into a high-precision dual cross-type sensor when an f/2.8 or faster lens is attached to the camera. Autofocus is not possible during viewfinder shooting with lenses having maximum apertures slower than f/5.6.
The system has an AF working range of EV -0.5 - 18 at ISO 100.
The number of AF points was increased, resulting in a 45-point AF system. Seven of these are high-precision cross-type AF points. Having this quantity of focusing points not only increases the flexibility in placing the focus within the image but it also improves the reliability of AI Servo focus tracking as the subject is more likely to be picked up by adjacent AF points.
Each AF sensor is indicated with a rectangular frame. AF points are arranged in a large oval pattern as shown in the illustration. The viewfinder coverage depends on the camera model. The illustration shows the viewfinder coverage of an APS-H camera where the AF points cover a fairly large portion of the image. On full frame cameras, a smaller portion of the viewfinder is covered.
This chip uses a ceramic package measuring 21.2 mm × 13.6 mm. The top is covered by clear glass. In contrast to previous sensor layouts, this chip does not feature distinct pairs of detector lines but rather rectangular arrays with countless tiny parallel detector lines embedded. The two larger dark rectangles are the vertical sensor arrays and the smaller dark rectangles are the horizontal detector arrays. This AF system requires comparatively large separator lenses. The two vertically aligned lenses cover all of the large detector arrays and the two horizontally aligned lenses cover the small detector arrays.
All 45 AF points are standard-precision vertical detectors (sensitive to horizontal contrast lines) designed for lenses having a maximum aperture of f/5.6 or faster. A row of seven AF points turns into high-precision cross-type detectors (sensitive to both vertical and horizontal contrast lines) if a lens with maximum aperture of f/2.8 or faster is attached to the camera. With cross-type autofocus enabled, vertical-line detection is about three times as sensitive as horizontal-line detection. For the center AF point, high-precision vertical-sensitive AF detection is even possible with lenses having a maximum aperture of f/4, and standard-precision horizontal-sensitive AF detection is even possible with lenses having a maximum aperture as small as f/8. With lenses having maximum apertures slower than f/8, autofocus is not possible during viewfinder shooting.
The system has an AF working range of EV 0 - 18 at ISO 100.
Compared to the previous 45-point AF system, the number of high-precision cross-type points was increased to 19.
Each AF sensor is indicated with a rectangular frame. AF points are arranged in a large oval pattern as shown in the illustration. There are 19 user-selectable AF points that are displayed with full opacity. The 26 Assist AF points are not selectable by the user and are displayed with reduced opacity.
This chip uses a ceramic package measuring 21.2 mm × 13.6 mm. The top is covered by clear glass. The actual detector lines are arranged in four rectangular dark zones as shown in the illustration. The separator lenses are comparatively large (same as previous type).
This AF system has 26 vertical Assist AF points and 19 high-precision cross-type points. The Assist AF points are standard-precision horizontal-sensitive only and are designed for lenses having a maximum aperture of f/5.6 or larger. The cross-type points are horizontal-sensitive to f/5.6 or faster and vertical-sensitive to f/2.8 or faster. With high-precision cross-type autofocus enabled, vertical-line detection is about two times as sensitive as horizontal-line detection. For the center AF point, high-precision vertical-sensitive AF detection is even possible with lenses having a maximum aperture of f/4, and standard-precision horizontal-sensitive AF detection is even possible with lenses having a maximum aperture as small as f/8. With lenses having maximum apertures slower than f/8, autofocus is not possible during viewfinder shooting.
The system has an AF working range of EV -1 - 18 at ISO 100.
Compared to the previous 45-point AF system, the number of high-precision cross-type points was increased to 39.
Each AF sensor is indicated with a rectangular frame. AF points are arranged in a large oval pattern as shown in the illustration. There are 6 vertical-only AF points that are displayed with reduced opacity. During manual point selection, all AF points are user-selectable and 39 cross-type points are available. However, these are reduced to 19 cross-type points during automatic point selection (with the remaining 26 AF points turning into vertical sensors).
This chip uses a ceramic package measuring 21.2 mm × 13.6 mm. The top is covered by clear glass. The actual detector lines are arranged in four rectangular dark zones as shown in the illustration. The separator lenses are comparatively large (same as previous type).
All 45 AF points are standard-precision vertical detectors (sensitive to horizontal contrast lines) designed for lenses having a maximum aperture of f/5.6 or faster. A total of 39 AF points turn into high-precision cross-type detectors (sensitive to both vertical and horizontal contrast lines) if a lens with maximum aperture of f/2.8 or faster is attached to the camera and manual point selection is used. With high-precision cross-type autofocus enabled, vertical-line detection is about two times as sensitive as horizontal-line detection. For the center AF point, high-precision vertical-sensitive AF detection is even possible with lenses having a maximum aperture of f/4, and standard-precision horizontal-sensitive AF detection is even possible with lenses having a maximum aperture as small as f/8. With lenses having maximum apertures slower than f/8, autofocus is not possible during viewfinder shooting.
The system has an AF working range of EV -1 - 18 at ISO 100.
Compared to earlier generations of AF systems, both the viewfinder coverage and AF point density have increased. All of the 45 AF points offer standard-precision cross-type autofocus capabilities.
Each AF sensor is indicated with small rectangular frames. AF points are arranged in three large rectangular zones. The illustration shows the viewfinder coverage offered by an APS-C camera. The coverage is smaller on a full frame camera.
The sensor uses the rectangular design that is covered in transparent optical polymer. The three zones of detector lines are clearly visible. The center area uses vertical lines with the zig zag arrangement to increase the autofocus accuracy. In general, the image shifts in phase detection systems are extremely small, even on the f/2.8 detectors. For this reason, dual-line zig zag detectors have also been used for the diagonal high-precision cross-type detector, increasing the resolution and therefore detection accuracy of the f/2.8 diagonal cross.
All AF points are standard-precision cross-type sensors designed for lenses having a maximum aperture of f/5.6 or faster. The center AF point turns into a high-precision dual cross-type sensor when an f/2.8 or faster lens is attached to the camera. For the center AF point, standard-precision cross-type AF detection is even possible with lenses having a maximum aperture as small as f/8. Depending on the lens attached to the camera, the number of usable AF points, AF point patterns or the types of AF sensors may vary. With lenses having maximum apertures slower than f/8, autofocus is not possible during viewfinder shooting.
The system has an AF working range of EV -3 - 18 (with the center AF point supporting f/2.8) at ISO 100.
The number of AF points was increased, resulting in a 61-point AF system. This system offers an increased accuracy not just for the center AF point but for all available AF points. Canon calls this 1st generation their High Density Reticular AF.
Each AF sensor is indicated with small rectangular frames. AF points are arranged in three large zones. On this 1st generation design, AF points are very densely packed with very small vertical spacing. The illustration shows the viewfinder coverage offered by a full frame camera.
The sensor chip is inside a ceramic package with a glass cover placed over the active area. One major innovation is the application of a dual-line zig zag arrangement to all of the detector stripes (vertical, horizontal, and diagonal ones) in all three zones. In addition, the detector's pixel pitch has been increased to improve AF accuracy even more.
Depending on the lens attached to the camera, the number of usable AF points, AF point patterns or the types of AF sensors may vary.
If a lens with a maximum aperture of f/2.8 or faster is attached to the camera, 41 AF points are standard-precision cross-type detectors, and 20 AF points in the outer zones are standard-precision vertical detectors. Out of the 41 cross-type sensors, five vertically arranged AF points in the center are high-precision dual cross-type detectors.
When a lens having a maximum aperture of f/4 is used, the 41 AF points remain standard-precision cross-type detectors and the 20 AF points remain standard-precision vertical detectors. However, the five high-precision dual cross-type detectors turn into regular standard-precision cross-type detectors.
When a lens having a maximum aperture of f/5.6 is used, all 21 AF points in the center zone remain standard-precision cross-type detectors but all 20 cross-type AF points from the two outer zones turn into standard-precision vertical detectors, resulting in 40 vertical sensors in the outer zones.
For the center AF point, standard-precision cross-type AF detection is even possible with lens and extender combinations having an effective maximum aperture as small as f/8. In addition, four AF points adjacent to the center AF point do also work at an effective maximum aperture of f/8. The two AF points to the left and right of the center are standard-precision vertical detectors and the two AF points above and below the center are standard-precision horizontal detectors. Autofocus is not possible during viewfinder shooting with effective maximum apertures slower than f/8.
The system has an AF working range of EV -2 - 18 (with the center AF point supporting f/2.8) at ISO 100.
Compared to the previous 61-point AF system, the number of f/8 compatible points was drastically increased. This 2nd generation AF system can autofocus with all 61 AF points when using a lens and extender combination having an effective maximum aperture of f/8, with up to 21 of those points being cross-type. This is a significant upgrade from the 1st generation, which only allowed the center AF point with surrounding AF points to autofocus at f/8. Canon calls this 2nd generation their High Density Reticular AF II.
Note how the AF points are slightly expanded vertically. This has slightly increased the viewfinder coverage that this 2nd generation system offers compared to the 1st generation.
The sensor chip is inside a ceramic package with a glass cover placed over the active area. Again, all detector stripes of all three zones use the dual-line zig zag design. The detectors again use the increased pixel pitch to improve AF accuracy even more. On closer inspection, it can be seen that the vertical pairs of detector stripes have been moved closer together than on the 1st generation chip.
Depending on the lens attached to the camera, the number of usable AF points, AF point patterns or the types of AF sensors may vary.
If a lens with a maximum aperture of f/2.8 or faster is attached to the camera, 41 AF points are standard-precision cross-type detectors, and 20 AF points in the outer zones are standard-precision vertical detectors. Out of the 41 cross-type sensors, five vertically arranged AF points in the center are high-precision dual cross-type detectors.
When a lens having a maximum aperture of f/4 is used, the 41 AF points remain standard-precision cross-type detectors and the 20 AF points remain standard-precision vertical detectors. However, the five high-precision dual cross-type detectors turn into regular standard-precision cross-type detectors.
When a lens having a maximum aperture of f/5.6 is used, all 21 AF points in the center zone remain standard-precision cross-type detectors but all 20 cross-type AF points from the two outer zones turn into standard-precision vertical detectors, resulting in 40 vertical sensors in the outer zones.
One significant feature of this AF system is that even with lens and extender combinations having an effective maximum aperture as small as f/8, the same 21 AF points in the center zone remain standard-precision cross-type detectors and 40 AF points from the two outer zones remain standard-precision vertical detectors (as if an f/5.6 lens was used). Autofocus is not possible during viewfinder shooting with effective maximum apertures slower than f/8.
The system has an AF working range of EV -3 - 18 (with the center AF point supporting f/2.8) at ISO 100.
The number of AF points was increased, resulting in a 65-point AF system.
Each AF sensor is indicated with small rectangular frames. AF points are arranged in three large zones. As this system is installed in an APS-C camera, viewfinder coverage is pretty impressive.
The sensor uses the rectangular design that is covered in transparent optical polymer. One pair of detector lines in the center and the diagonal detectors use the dual-line zig zag detector layout to improve accuracy.
Depending on the lens attached to the camera, the number of usable AF points, AF point patterns or the types of AF sensors may vary.
If a lens with a maximum aperture of f/2.8 or faster is attached to the camera, all 65 AF points are standard-precision cross-type detectors, and the center AF point is also a high-precision dual cross-type detector.
When a lens having a maximum aperture of f/5.6 is used, all 65 AF points remain standard-precision cross-type detectors but the high-precision dual cross-type detector at the center turns into a regular standard-precision cross-type detector.
For the center AF point, standard-precision cross-type AF detection is even possible with lens and extender combinations having an effective maximum aperture as small as f/8. In addition, four AF points adjacent to the center AF point do also work at an effective maximum aperture of f/8. The two AF points to the left and right of the center are standard-precision vertical detectors and the two AF points above and below the center are standard-precision horizontal detectors. Autofocus is not possible during viewfinder shooting with effective maximum apertures slower than f/8.
The system has an AF working range of EV -3 - 18 (with the center AF point supporting f/2.8) at ISO 100.
The number of AF points was drastically increased, resulting in a 191-point AF system. This AF system delivers the fastest and most precise focusing that has ever been achieved by the phase detection approach. In addition, it provides a new level of AF tracking supported by deep learning, including head detection, face detection, and people prioritization. On most other Canon DSLR cameras, autofocus data is processed by the camera's CPU called DIGIC which is responsible for all data processing. By contrast, the enormous amounts of autofocus data produced by this 191-point AF system is analyzed by a dedicated Canon DIGIC 8 chip which is used as a powerful co-processor to the even more powerful DIGIC X central processing unit.
The dotted position indicators are arranged in three zones. During focusing, each active AF point turns into a small pixelated square. Viewfinder coverage is roughly the same as on the predecessor (2nd generation 61-point AF system).
This sensor chip is a complete innovation for a phase detection system. Instead of small pairs of linear detector strips, this new AF sensor uses arrays of tiny square pixels (pixel-dot-matrix). These light receptive surfaces are arranged in three zones. Detector pixels are 28 times denser than in the previous 61-point AF sensor of the EOS 1D X II. The total number of pixels used is roughly 100 times higher than in the previous system. This results in a significant boost in autofocus precision.
The maximum number of available AF points is 191. Depending on the lens attached to the camera, the number of usable AF points, AF point patterns or the types of AF sensors may vary.
If a lens with a maximum aperture of f/2.8 or faster is attached to the camera, 155 AF points are standard-precision cross-type detectors, and 36 AF points in the outer zones are standard-precision vertical detectors. Out of the 155 cross-type sensors, the center AF point is also a high-precision dual cross-type detector.
When a lens having a maximum aperture of f/4 is used, the 155 AF points remain standard-precision cross-type detectors and the 36 AF points remain standard-precision vertical detectors. However, the center high-precision dual cross-type detector turns into a regular standard-precision cross-type detector.
When a lens having a maximum aperture of f/5.6 is used, all 65 AF points in the center zone remain standard-precision cross-type detectors but all 90 cross-type AF points from the two outer zones turn into standard-precision vertical detectors, resulting in 126 vertical sensors in the outer zones.
The autofocus capabilities with effective apertures of f/8 is similar to the latest 61-point AF system. With lens and extender combinations having an effective maximum aperture as small as f/8, the same 65 AF points in the center zone remain standard-precision cross-type detectors and 126 AF points from the two outer zones remain standard-precision vertical detectors (as if an f/5.6 lens was used). Autofocus is not possible during viewfinder shooting with effective maximum apertures slower than f/8.
The system has an AF working range of EV -4 - 21 (with the center AF point supporting f/2.8) at ISO 100.