Canon EOS 20D
Encyclopedia
The Canon EOS
20D is an 8.2-megapixel semi-professional digital single-lens reflex camera
, initially announced on August 19, 2004 at a recommended retail price of US$1,499. It is the successor of the EOS 10D
, and was succeeded by the EOS 30D
in August 2006. It accepts EF
and EF-S
lenses and uses an APS-C
sized image sensor.
. The 20D supports USB 2.0. The 20D has a larger buffer and can shoot more frames per second. It also uses the E-TTL II flash metering system and uses the DIGIC II image processor.
The EOS 20D (with appropriate firmware updates) can also accept the Canon Wireless File Transmitter WFT-E1/E1A for fast file transfer to a remote file server, either through an ethernet
cable or a Wi-Fi
network.
camera to use the EF-S lens mount; the first Canon EOS
camera to use the mount was the 300D
(the Digital Rebel in North America).
. On June 1, 2005 Canon announced that the 20Da would be made available worldwide.
The main differences between the 20Da and 20D are the replacement of the "hot mirror" infra-red (IR) filter which covers the CMOS
sensor on the 20D and live view mode.
In conventional photography, the IR filter is used to make the spectral
response of the CMOS sensor more like that of the human eye. In this way, the pictures gathered by the sensor more closely resemble the world as we see it. In astro-photography, many objects of interest emit strongly in the red H-α line, which is heavily attenuated by the IR filter on the 20D. The IR filter of the 20Da passes 2.5 times more light at around this 656 nm wavelength as the filter of the 20D, allowing more fine detail to be revealed in long exposures of emission nebula
e. As a side effect, the color balance is slightly altered in normal daylight photography.
It is extremely difficult to focus an extremely dim image with a reflex viewfinder; locking the mirror up and opening the shutter (live view) was introduced in the 20Da to address this issue. When used the camera provides a live image of the center of the field of view to allow focusing on a bright star. Live view for this application requires a lens which supports fully mechanical focus in manual mode, and is not suitable for normal daytime use.
Reviews report that image noise in the 20Da is lower than in the 20D.
The EOS 20Da was discontinued when the 30D was introduced in 2006. Canon has produced no similar model for astrophotography since, though many astrophotographers commonly make similar aftermarket modifications to later Canon models to fill the same role.
Canon EOS
The Canon EOS autofocus 35 mm film and digital SLR camera system was introduced in 1987 with the Canon EOS 650 and is still in production as Canon's current DSLR system...
20D is an 8.2-megapixel semi-professional digital single-lens reflex camera
Digital single-lens reflex camera
Most digital single-lens reflex cameras are digital cameras that use a mechanical mirror system and pentaprism to direct light from the lens to an optical viewfinder on the back of the camera....
, initially announced on August 19, 2004 at a recommended retail price of US$1,499. It is the successor of the EOS 10D
Canon EOS 10D
The Canon EOS 10D is a discontinued 6.3-megapixel semi-professional digital SLR camera, initially announced on February 27, 2003. It replaced the EOS D60, which is also a 6.3-megapixel digital SLR camera. It was succeeded by the EOS 20D in August 2004....
, and was succeeded by the EOS 30D
Canon EOS 30D
The Canon EOS 30D is an 8.2-megapixel semi-professional digital single-lens reflex camera, initially announced on February 21, 2006. It is the successor of the Canon EOS 20D, and is succeeded by the EOS 40D...
in August 2006. It accepts EF
Canon EF lens mount
Introduced in 1987, the EF lens mount is the standard lens mount on the Canon EOS family of SLR film and digital cameras. EF stands for "Electro-Focus": automatic focusing on EF lenses is handled by a dedicated electric motor built into the lens...
and EF-S
Canon EF-S lens mount
The EF-S lens mount is a derivative of the EF lens mount created for a subset of Canon digital single-lens reflex cameras with APS-C sized image sensors. It was released in 2003. Cameras supporting the EF-S mount are backward-compatible with the EF lens mount and, as such, have a flange focal...
lenses and uses an APS-C
APS-C
Advanced Photo System type-C is an image sensor format approximately equivalent in size to the Advanced Photo System "classic" size negatives...
sized image sensor.
Improvements
The 20D features a new sensor and a greater megapixel count (8.2 megapixels instead of 6.3) and retains the Canon 1.6x crop factorCrop factor
In digital photography, a crop factor is related to the ratio of the dimensions of a camera's imaging area compared to a reference format; most often, this term is applied to digital cameras, relative to 35 mm film format as a reference. In the case of digital cameras, the imaging device would be a...
. The 20D supports USB 2.0. The 20D has a larger buffer and can shoot more frames per second. It also uses the E-TTL II flash metering system and uses the DIGIC II image processor.
The EOS 20D (with appropriate firmware updates) can also accept the Canon Wireless File Transmitter WFT-E1/E1A for fast file transfer to a remote file server, either through an ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
cable or a Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
network.
Features
The 20D is the first Canon prosumerProsumer
Prosumer is a portmanteau formed by contracting either the word professional or less often, producer with the word consumer. For example, a prosumer grade digital camera is a "cross" between consumer grade and professional grade...
camera to use the EF-S lens mount; the first Canon EOS
Canon EOS
The Canon EOS autofocus 35 mm film and digital SLR camera system was introduced in 1987 with the Canon EOS 650 and is still in production as Canon's current DSLR system...
camera to use the mount was the 300D
Canon EOS 300D
The Canon EOS 300D, manufactured by Canon, marketed in North America as the EOS Digital Rebel, and in Japan as the EOS Kiss Digital, is a 6.3-megapixel entry-level digital single-lens reflex camera. It was initially announced on 20 August, 2003 at a price point of $899 without lens, $999 with the...
(the Digital Rebel in North America).
EOS 20Da
Canon released the EOS 20Da on February 14, 2005 in Japan. It is a variant of the 20D designed for astrophotographyAstrophotography
Astrophotography is a specialized type of photography that entails recording images of astronomical objects and large areas of the night sky. The first photographs of an astronomical object were taken in the 1840s, but it was not until the late 19th century that advances in technology allowed for...
. On June 1, 2005 Canon announced that the 20Da would be made available worldwide.
The main differences between the 20Da and 20D are the replacement of the "hot mirror" infra-red (IR) filter which covers the CMOS
CMOS
Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...
sensor on the 20D and live view mode.
In conventional photography, the IR filter is used to make the spectral
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
response of the CMOS sensor more like that of the human eye. In this way, the pictures gathered by the sensor more closely resemble the world as we see it. In astro-photography, many objects of interest emit strongly in the red H-α line, which is heavily attenuated by the IR filter on the 20D. The IR filter of the 20Da passes 2.5 times more light at around this 656 nm wavelength as the filter of the 20D, allowing more fine detail to be revealed in long exposures of emission nebula
Emission nebula
An emission nebula is a cloud of ionized gas emitting light of various colors. The most common source of ionization is high-energy photons emitted from a nearby hot star...
e. As a side effect, the color balance is slightly altered in normal daylight photography.
It is extremely difficult to focus an extremely dim image with a reflex viewfinder; locking the mirror up and opening the shutter (live view) was introduced in the 20Da to address this issue. When used the camera provides a live image of the center of the field of view to allow focusing on a bright star. Live view for this application requires a lens which supports fully mechanical focus in manual mode, and is not suitable for normal daytime use.
Reviews report that image noise in the 20Da is lower than in the 20D.
The EOS 20Da was discontinued when the 30D was introduced in 2006. Canon has produced no similar model for astrophotography since, though many astrophotographers commonly make similar aftermarket modifications to later Canon models to fill the same role.