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The Canon 20D

  Type  Digital SLR
Shutter Range 1/8000 to 30 seconds
Shutter Type Vertical Travel, Electronically Timed Focal Plane
Meter Type CMOS
Meter Range EV1 - EV20
Exposure System 35 zone TTL
Lens Mount Canon EF Autofocus
Battery BP-511
Digital Specs
Sensor Type CMOS  
LCD Display 1.8" - 118K
Sensor Size 22.5x15 mm Recording Media Compact Flash
Sensor Resolution 8.2 MP File Size 3.6 - 8.7 MB
Focal Length Compensation 1.6 Film Speed Equiv. 100 - 3200
    The Canon 20D was introduced in 2004. It was the fourth generation Canon "prosumer" model - part way between a consumer grade and a professional grade camera. It was not until the 40D was introduced in 2007, that this camera was seriously improved upon. The intermediate model 30D was a decent camera, but used the same imager, and had few improvements making it worth the upgrade. As the 20D is over ten years old, and has been superseded by several newer models, it is quite the photographic bargain these days. Costing around $1500 new, as a used camera it can be picked up for a tenth that price or even a bit less. I bought this camera used, and was quite pleased.
    Like all of the D series cameras, this is a semi-professional grade camera with high resolution and the flexibility of the full range of Canon lenses. Even so, there are a number of features meant to appeal to the casual, or snapshot photographer. So it is a camera that you can grow into. The autofocus feature comes to mind, as does the option for fully programmed exposure. There is also a series of AE settings collectively referred to as the Easy Shooting Zone. Each member of the series is pre programmed to give good results taking the following types of shots:
  • Portrait (Low Aperture, center spot metering)
  • Landscape (High Aperture, averaging metering)
  • Close up
  • Sports (high shutter speed)
  • Night scenes (Auto flash, combined with slow shutter speed)
  • Flash off
        The Creative Zone, is what Canon calls it's series of more traditional, non programmed exposure modes. These modes are
  • Manual exposure
  • Aperture Priority
  • Shutter Priority
  • Automatic Depth of Field
        Most photographers are familiar with how these types of auto exposure work, with the exception of the strange Auto depth of field setting. This setting checks all of the focus points, in the camera's viewfinder, and sets focus, and aperture, so that they will all be in focus. Back in the old days, a photographer would simply use a higher aperture, or perhaps stop down to check depth of field. While this setting probably does the same thing, it is better to know what you are doing.
    The images are stored on Compact Flash media. Type I and type II are supported, as well as fat 32, so that large cards may be used. The images can be stored in three resolutions: large (3504x2336), medium (2544x1696), or small (1728x1152), and two qualities: normal or fine. This gives a total of six different image modes. The quality setting determines the amount of compression that will be used to store the image. Compression is a tricky thing. Though it does not technically change the resolution, at high compression levels image quality suffers, and "artifacts" of the compression algorithm can sometimes be noticed.
     Images with many changes, and textures tend to suffer more from this effect, than less complex compositions. For the real die hard, there is the option to save the images in the RAW format, with no compression at all. The RAW format is not just an uncompressed format. It saves the images as the sensor sees them, by turning off a function of the processor chip known as the Bayer Interpolation. You may be surprised at how different your images look under RAW. I should mention that RAW images can not be used in their native format, and must be processed before display. Most viewers will not be able to open a RAW file, and Canon includes a special program to do this.
     The raw image file is 8.7 mb in size, compared to 3.6 for large/fine, 1.8 for large/normal, 1.2 for small/fine, and .6 for small/normal. A 1gb drive gives a capacity of 114 RAW photos, or 277 on large/fine. On small/normal, you can fit 1062 shots per GB.
    The heart of any digital camera is it's imager. The imager, processor, and the storage media combine to do the same job as the film of a conventional camera. In the 20D, this is a small CMOS unit, developed by Canon for still photography. The photographs taken with the 20D are rich, crisp, and clear. Pictures may be viewed on the 1.8" 118K LCD on the back of the camera. This is also where detailed settings and parameters may be viewed are set. The LCD image is zoomable and panable.
        I am, at heart, a manual shooter, and rarely use any of the Creative Zone settings. The Manual setting makes this pretty simple. When set to manual, the dial on the camera back controls the aperture, and the thumbwheel on the top of the grip controls the shutter speed. Proper exposure, as determined by the camera metering system, is displayed on a scale at the bottom of the viewfinder, with a mark indicating how far the manual settings diverge from the camera selected settings. Even better, the meter can be set for center weighted, evaluative, or partial metering. When set to partial metering, a small area (9%) is metered. This is wonderful for strongly backlit or front lit scenes, and will work well, as long as the photographer is aware, in any scene.
        The photo to the right shows the top of the 20D, with the mode dial to the left, and the thumbwheel control and shutter release on the grip to the right. Also to the right is the top mounted display. The display indicates the camera is in manual mode, with settings of 1/60 of a second and F 8.0, as well as evaluative metering, and single shot mode.
        Sadly, as with all of the EOS cameras, manual focus is difficult. Because these cameras (like all current models) are so dependant and oriented towards auto focus, there is no real provision for manual, and the meter contains no focusing aids. So while the autofocus can be turned off on the lens, it can be difficult to get a precise focus manually, particularly in poorly lit scenes. The biggest problem that most photographers have with autofocus is that it so often picks the wrong focus points, and can sometimes be a bit slow. The 20D has a "joystick" toggle on the back that can be used to select the desired focus point, of the nine available in the viewfinder; but by the time you screw around with all of this, compose and shoot, you could have more quickly just focused yourself - if there had been a focusing aid in the viewfinder.
        I also generally leave the camera to AWB (Auto White Balance) for color rendition. There are a number of parameter settings and filter settings you can use in this camera; but I prefer to keep things simple. If I need to make any changes, I do them post processing in Photoshop. I frankly don't like to let the camera do too much of my thinking or adjusting for me. The whole point of getting a really good camera is so that you can have full creative control.
        The left hand side of the camera has buttons for setting the built in flash, and to stop the lens down for depth of field preview. This is also where the lens release button is located.  Under a protective cover, it has connectors for video out, digital, a remote control, and an old fashioned PC connector for flash.
The Effect of Film Speed on Image Quality of the 20D

A tightly cropped photo of my desk at home in normal room light.  ASA 400 is to the far left, and ASA 1600 is to the right. For comparison sake a shot at ASA 100 is just to the left. Though there seems little difference between 100 and 400, the difference between 400 and 1600 is distinct. I usually shoot at 400.

      The imager of the 20D is capable of operating at film speeds ranging from ASA 100 to ASA3200. The higher film speeds bring with them the traditional disadvantages well known to generations of film photographers. Chief among these are noise, and reduction of gray scale. In film cameras, this is produced by the need for larger, more irregular grains of silver halide, needed to work with smaller amounts of light. This tends to make the pictures grainier.
        On digital cameras, noise is an artifact of the natural, random signals given off by the sensor. These signals are generally below the threshold of the signals produced by the light striking the face of the sensor, and are overpowered by them. As the light intensity drops, these lower level signals become noticeable. Another problem of operating at low light levels, using fast speeds, is the problem of loss of contrast, and color saturation. still, a higher ASA rating will get you a picture that might not be possible with a lower setting.
        The photo to the right shows the 20D in clean mode, with its mirror up to allow access to the imager. The imager itself is the small blue/green square visible at the rear of the mirror box. The mirror itself is that slab of glass seen flipped up on the roof of the mirror box. Also visible are the EOS electrical contacts, towards the bottom of the lens mount.
    If there is any real handicap to using a digital camera, it is the constraint placed upon the digital photographer of always using the same imager, no matter what the conditions or effect desired. The old time film photographer had a distinct advantage here, because of the film camera's capability of being loaded with any of a multitude of films being produced. Film photographers have bulk loaded everything from commercial movie film to 35 mm microfilm into their cameras. There is also a selection of special purpose films such as Infra Red, High Contrast, and false color films.
    One of the ways that digital cameras fight back, and get more versatility, is by the use of film speed settings, and quality settings (parameters can also be used, but I do not use them, or know enough about them to really comment). This gives the user a bit of versatility, though not to the degree of that enjoyed by the film photographer. Still, the technology is moving along, and who can say what types of imagers might be a few years down the road.
    One thing for the owner of a DSLR to watch out for is dust on the imager. It's going to happen, no matter how careful you are. Most cameras actually leave the factory with some dust on the imager. And it is a dusty world. Every time you change a lens, some dust gets in. Additionally, cameras mechanicals wear against each other, creating dust. The problem is more noticeable as you use higher apertures.
The Effect of Image Quality Settings on the Canon 20D
High Quality
Enlarged sections of photos taken of the same subject, with the same exposure, under the same conditions. Only the quality level is changed. I always shoot at high. Memory is cheap.  
Average Quality
     In addition to the film speed setting, the 20D offers the option of three resolutions, and two quality levels. The purpose of different levels of resolution is intuitively obvious. The selection of quality levels is not really an artistic or an adaptive control. The main function of the selection of quality levels is to give the photographer some control over the file size of the images produced. This is done by selecting between different levels of compression when the images are being stored. In the 20D, images are generally stored in the JPEG format, which is a compressed format. Compressed formats use algorithms to look for patterns so that they can throw details away, and give smaller file sizes. These same algorithms are used when the image is viewed, to reconstruct the details that were taken out. Naturally, nothing conforms exactly to any pattern or algorithm, and bits of the detail will not be reconstructed. At higher compression levels, you get smaller files, but less accurate reconstruction all the fine details. The more irregular, textured, or busy a scene is, the more the compression effect will be noticed. The best candidates for high compression are sunsets, and wide open vistas. The worst subjects for high compression are diagrams, printed pages, or anything with a considerable amount of detail or contrast.

    The meter will set exposure down to EV 1, at a rated sensitivity of ASA 100. With an f 1.4 lens, this is a 1 second exposure. With the standard F 3.5 lens that comes with most kits, this would be an 8 second exposure. The meter breaks the image up into 35 different zones of measurement. This gives the capability of setting up a number of different metering patterns for different  types of situations. This is what makes the Easy Shooting Zone settings possible. So for landscapes, the metering pattern will be bottom weighted, under the assumption that the upper portions of the frame will be filled by the relatively bright sky. For portraits, semi spot metering will guarantee that a face which fills the center of the composition, as is the case in most portraits, will be perfectly exposed. For Close ups, center weighted is just the thing. My favorite feature is a resurrection, of sorts, of the old TTL semi spot metering of the old F series. When this option is chosen, the EOS series does the old FD cameras one better by using a 9% circle, as opposed to the FD 12% rectangle. This is the only metering setting that I use.
    The photographer has two ways to view his work. The first, and most obvious, is through the viewfinder. As a reworked SLR, the 20D has a regular eye level, pentaprism viewfinder for through the lens viewing via a ground glass screen. The eyepiece has a dial to give up to 2 diopters of visual correction, for users who wear glasses. The viewfinder itself displays the nine focusing marks (user selectable, of course), along with shutter, aperture, flash, and autofocus information. There is also a slightly shaded ring, which shows the metering area when semi spot metering is selected. What is missing from the viewfinder, in this autofocus camera, is any kind of focusing aid. This can make precise focus with a non autofocus lens, rather difficult, particularly when using slow lenses.
     The viewfinder is shown in the photo to the right. Visible is the central circle which shows the metered area when using partial metering. The nine focus points show up clearly, and flash red when selected manually, to indicate the chosen focus point. The bottom display shows the camera is set at 1/100 shutter speed, with an aperture of F 10, and is at least two stops underexposed when compared to auto exposure. The green dot far to the left indicates focus lock, and the number nine shows that there is room for at least nine rapid fire shots in the buffer.
    To check photographs already taken, there is a built in color LCD screen on the camera back. The screen can not be used to compose or preview photographs, as it only displays what has already been stored in the memory. The resolution of the 1.8", 118,000 pixel LCD is about half that of a standard VGA monitor, and not too far inferior to that of the sensors on cameras from just a decade ago. There is more to the LCD screen than a fancy way to view your images. The images can be zoomed in on, and the screen can also be used to view camera settings. On top of all of this, Canon has included a way to display histograms, charts of color balance, brightness, contrast etc., on this display. This is not a feature that I use, preferring to view and adjust these levels in Photoshop (if at all), but some users might find them convenient.
    Two dials control most of the operations of the camera. The dial to the left of the pentaprism, selects the shooting mode, while the dial to the right sets the exposure. It is possible to use the camera, while never touching another control, other than the power switch. For those who enjoy a bit more creative control of their image, the 20D is able to oblige. In addition to the easy Shooting Zone Settings, and the  Creative Zone settings, the camera has exposure compensation, and the option of setting parameter definitions, which allow for customizing the color balance, brightness, contrast, and  intensity. Different sets of parameters can be defined as sets, so that the demanding photographer can create a special parameter set for indoor lighting, another for cloudy days, and still another for bright sun.

Personal Observations:

        This camera is very similar to my old D30, and somewhat similar to my Digital Rebel. These are substantial cameras, with metal frames, and sturdy bodies. They have the full range of expected features, auto exposure and focus, a TTL system for flash, various parameters and custom settings, a rear LCD for instant photo viewing, and a built in flash. The 1/8000 top shutter speed is the same as that on Canon's current models, and though higher resolution cameras are available (I have several), the 8.2 MP resolution is more than enough for most situations, and I use this camera often.

        This was the first model capable of taking the new EF-S type lenses. The lenses are similar to the standard EF lenses, except that they have the rear element closer to the film plane. They also focus to a smaller image. They are more suited to the APS-C size sensor, and the image does not need to cover the entire 35mm frame. The biggest advantage of the S series of lenses is that they can be made somewhat smaller, lighter, and less expensive. The disadvantage is that if you were to use such a lens on a standard 35mm camera, the image would vignette, and not cover the full frame.
        The 20D shares the autofocus feature of all of the EOS line, in common with almost every camera made these days. It is very difficult to find a manual focus camera, and most consumers have been brainwashed into believing this is a must have feature. I have gotten used to autofocus; but never learned to like it. Most photographers can do the job faster, and there are some situations, notably low light, under which autofocus does not work. There is also a problem, with certain compositions, of getting the camera to focus on the right subject. There are options to set, the 20D has nine different focus points, but the whole thing would really be much easier and faster with manual focus. With autofocus being a standard feature these days, viewfinder focusing aids have become a thing of the past, except for some expensive aftermarket focus screens. The user has little choice but to rely on autofocus, stop down, or settle for pictures which are somewhat unsharp. This is my biggest complaint about the new generation of autofocus SLR cameras.
        The 20D has a built in flash, which pops up from the top of the pentaprism housing when the camera meter decides that it is needed. The unit is fully integrated with the camera meter system, and has an ASA100 rating of 43. This is more convenient than I had first thought, and the flash comes in very handy for snapshot type photography, and even more handy as a fill flash for taking some of the contrast out of brightly lit scenes. For the more demanding or flash dependent photographer, Canon offers a number of very capable flash units which are able to fully integrate themselves with the camera's metering, and focusing systems.

       My best friends on this camera, are the exposure hold button, and the manual override. The exposure hold button is the easiest way to get by the computer automation, or to photograph off center subjects, and still get a proper exposure. It works best when the meter is set for 9% partial metering. There is an exposure compensation system, for backlit, offset, or oddly colored scenes, but I have never had good results with exposure compensation; it takes too long, and requires too much guesswork. After getting used to the system, I can now quickly set the aperture and shutter speed after metering. I can then leave them while the camera finds its focus. This is almost as fast as my old manual match needle camera.

        As with all of the current crop of digital cameras, you can shoot all day (sometimes all week) without changing the memory chip.  Batteries are another matter, and might only last for 1000 or so shots at the most; but batteries are cheap, chargers are small, and spares can be brought. I have never run out of memory without having run down my battery first. In answer to this, Canon offers it's battery grip, which fits seamlessly on the bottom of the camera, a bit like a motor drive, and plugs into the battery compartment of the camera. It holds two standard 2200 mah BP-511- batteries, or six AA batteries of up to 2600 mah.

        With the battery grip, and the 8 GB memory card that I ordinarily use, this camera can take approximately 2000 photos before recharging or using another card. This should be enough for even the most insatiable photographer.

    The camera comes with a battery, charger, USB cable, and AC adapter. The ac adapter works by plugging into a receptacle on the charger. Once connected, the adapter goes into the camera battery compartment. Canon also offers a cigarette lighter adapter. There is a radio controlled remote unit, and numerous flash options. The most important accessory is the availability of the entire series of Canon EF lenses.
        This is a great camera, far nicer than my original D30, that I got back in 2000, and quite a bit nicer than my Rebel, though not quite as nice as my 50D. I suspect the 70 D is even better, though as of this writing I have yet to get my hands on one. Digital cameras continue to evolve, yet some of these older models are still great picture taking tools, and are available at a fraction of their original cost. The major limitation of this camera is its 8.2 MP sensor, yet plenty of weddings, nature shots, and magazine photos have been taken with far less (3.2 MP on the 30D was used by many professionals for years).
        The resolution wars being engaged in by the major camera manufacturers remind me a bit of the horsepower wars being fought by the major auto makers back in the 60's/70's. In both cases we are being offered capacities that we don't need and most of us will never come near to using. The guy that bought the 500 HP muscle car back in the late sixties, probably never drove it much past 60. The guy who buys the top of the line 24 MP camera will probably never view his photos at much more than the 1920 x 1080 (2 MP) resolution of today's HD television, or the typical 1440 x 900 resolution of the average PC (1.3 MP). he will probably never print any photos at better than the standard 300 dpi standard.
        For most photographers, under most conditions, this is all the camera you will need. When compared to Canon's latest offerings, the 20D will take all the same lenses, including the newer EF-S type, has the same maximum 1/8000 shutter sped of the latest models, as well as a sturdy metal frame, and costs a fraction of the newest offerings. Unless you need the full 18 or 20 megapixels - why spend the money?