I am familiar with Canon's EOS 1 D Mark III and
1 Ds Mark III.
The former, with its extreme rates of up to ten pictures i use with fast action and when I need to exceed 1600 in the ISO (because of low noise). The image files of 12 megapixel accept even some cropping.
EOS 1 Ds model with 22 megapixel do I use when a frame of five pictures in seconds is enough and when I have enough light to avoid having to go over the ISO 800-1600. Then is it in it's own class in terms of image quality.

What I had in hand in July proved to be an advanced amateaur body or semipro with a 15 Megapixel sensor and 6.3 images per second. I have not photographed with the earlier XXD models apart from 10 D. Despite the instruction manual was missing, it took only a few minutes to get acquainted with the features of the new 50D.
What interested me first and foremost with the camera was how th AF would react. According to oral information, it would be fitted with a new DIGIC IV processor, which would further improve the auto performance.

Before I went out with my rental boat to photograph Gulls, I wanted to test the AF on dry land. In the one-shot mode, I put the focus on my 300 / 2.8 IS on infinity and i focused on the gravel three feet away and pressed down. I repeated the process with different motives closely adjacent and the AF sat there with surprising speed every time. Amazingly fast I must add.
I tested the camera with 70-200/2,8 and set the AI Servo while I quickly panned down from the beach 200 feet away on the other side of the water to the surface of the water a few metres in front of me. The focus tracked fine all the time.

When I took up my EOS 1 D Mark III and did the same thing the result was less convincing, I have experienced Mark III-s as fast, but EOS 50 D was clearly faster. I repeated the manoeuvre a dozen times with two cameras.
När det i alla fall gäller stillastående motiv är min bedömning att EOS 50D har världens troligen hittills snabbaste autofokus.
When the motive is still its my assessment that the EOS 50D has probably the world's fastest AF.

The next question was how the camera would work out in the field. To photograph flying birds belongs to the most difficult and most challenging you can expose a camera for in terms of AF.

The new EOS 50D with EF 300 / 2.8 IS and EF 70-200/2, 8 IS with and without 1.4 TC managed for the most part to follow the Gulls which flew after the boat or who flew at me when we anchored. If i aimed correct and gave the camera few tens of a seconds to react i always got sharp images. When it was not sharp, it was I who had missed having the bird in the centre. I used AI SERVO AF with only the central focus point active.

To further test the AI Servo i tried to shoot with all AF points activated. I also stopped down a bit to further increase the DOF. To my surprise, the new EOS 50D with 70-200/2,8 and 300/2.8 worked quite well following birds even with all the AF-points activated. I do not think it works always, but this was clearly better than in any previous camera, I tried.

The speed of 6.3 images per second is sufficient to be able to capture the eagle wings in different positions. My experience tells me that the critical point is located somewhere of about five pics per seconds. Is the speed higher than you can capture wings in different positions with most birds, including birds of prey and owls.

Compared to MKIII with the ten pic per seconds it is of course a difference, but in practice it is rarely i would miss the images because to lover 6.3 FPS.
Back in my hotel room I checked the image files. Unfortunately I had been forced to take photographs in JPG format, since none of the RAW converters didnt work with the 50D files. The files were larger than I had expected. I had expected a 12-13 mpix sensor but the 50D have 15 mpix.

Image size of 15 megapixels give me as a photographer great opportunities to crop the images sharply and still use them for example, as a full page in a book (with some interpolation). Large image files is especially important for bird photographers. How many times is your framing perfect when shooting with only the center AF point active? Anyone who photographed birds know that now and then you have to crop.

To see what the 50D is capable of ISO wise, I shot high ISO speeds (ISO 640 to 1600) almost all the time. Unfortunately, I had no way in such a short time to make a proper test. My feeling is that noise level is low, especially given the fact that I had to work with jpg files, and that Canon pressed in as much as 15 megapixels in a APS-C-sensor (22.3 x 14.9 mm).

Another feature that was introduced already with the previous model wasthe Highlight Tone Priority. Its purpose is to save highlights from getting burned out. I have earlier mentioned in my blog the difficulty of exposing a white bird right against a dark background. Although the white bird occupies a relatively large surface area (25-35%), a darker background steals much light and fool the to think camera think that the subject as a whole is darker - and therefore expose brighter than the white bird actually tolerate. This applies to all cameras and brands.

When I tested the EOS 50D I shot with Auto WB, something I normally never do in JPEG mode. Only when I shoot in RAW format I usually dare to shoot in Auto because I always can change WB after. But now I wanted to see how well the Auto WB worked.

In 50% of the cases, I was completely happy, but when I had water in the frame and a little warmer evening light the camera tried to switch WB. I therefore recommend that at least when shooting in JPEG, where possible, itself set the WB to have complete control.

In the case of flash automatic my experience is that they often underexpose, which certainly is better than the opposite. I had no expectations when I took a few test with the built-in flash on the EOS 50D.I used Auto and photographed a face that occupied 15-20 percent of the fram with a very dark background. I then photographed a room with white walls, and a number of different motives. I have no experience of the previous cameras in the series, 30D and 40D, and I am surprised that automatically managed all these situations. The white walls were not gray but remained white, the WB also acted well.

I had only three days to test the camera and based on that limited i felt felt the camera very easy to work with. I have never before been so fond of smaller cameras but preferred a larger body to grip. But even without the grip the 50D felt comfortable. And after three days with a light body, I must admit that it has its obvious benefits to the heavier 1 series.
LCD screen was bright and big enough that I could easily control the image quality - and the histogram.

With the expanded file size of 15 megapixels, a frame rate of 6.3 images per second and with perhaps the fastest AFs on any camera the only one thing I could swear over was when Canon Representative wanted to pack the camera in the anonymous package again. Possibly could be one more thing to concern me. When the price of 1000-1200 € allows the majority (in our part of the world) to buy a body which in many ways is in class with the best pro bodies, yes how much difference is it between pro's equipment from amateur photographers?

The latter, I take that as a professional challenge.