Roughly a year after releasing the EOS 40D, Canon has continued the popular "xxD" series with the 50D. As they have done before, Canon has made small, but useful incremental updates with the 50D.

This table shows the evolution of the "xxD" models:

Model	Date Announced	Resolution	LCD Screen
D30	4/2000	3.1MP	1.8"
D60	2/2002	6.3MP	1.8"
10D	2/2003	6.3MP	1.8"
20D	8/2004	8.2MP	1.8"
30D	2/2006	8.2MP	2.5"
40D	8/2007	10.1MP	3.0"
50D	8/2008	15.1MP	3.0"

Resolution goes upfrom 10 to 15 megapixel. The LCD screen is the same size (3.0") but the resolution has quadrupled - from 230,000 pixels to 920,000. This matches the screens on the Nikon D300 and D90 and the increase really makes a difference when checking focus and color. The 50D also gains an HDMI output to allow you to view your images from the camera on an HD television (HDMI cable not included).

Live View gets a third autofocus mode called "face detection" that identifies a face in the frame and tracks it to lock focus. There is also a dedicated Live View button that makes it easier to activate Live View.

Live View allows you to use the LCD screen as a viewfinder, although it is mainly designed for use in manual focus mode. If you wish to use Live View with autofocus, it is a bit convoluted and can only work with static subjects. You must hold the camera still, press and hold a button until the camera beeps, release the button and the press the shutter to take the photo. There may be uses for Live View outside the office, but we don't see it being used very often for clinical photography.

Like the 40D, the 50D also gets interchangeable focusing screens and
a grid screen is available. The grid screen superimposes horizontal and vertical lines in the viewfinder. This was a very popular upgrade back in the days of the Yashica Dental Eye and should be very useful for image alignment. We can install this focusing screen for you when we assemble your camera system (and the original screen will be sent
as well).

Canon designed the 50D to be compatible with most of their EOS 35mm camera accessories, including the Canon MR-14EX macro ring flash and the Canon MT-24EX dual point flash. This allows E-TTL (evaluative through-the-lens) flash metering for automatic exposure. Just as you would with a 35mm clinical camera, you simply set the magnification and f-stop and then move towards your subject until the image is in focus - the 50D takes care of the rest. Or switch the lens to AF (auto focus) and let the camera do the focusing. You have the choice.

Click image for larger view.Image is representative of the complete system.
Individual components will vary depending on system configuration.