With the 10.1MP EOS 40D as their main "advanced amateur" or "prosumer" level camera Canon had received some criticism on the grounds that almost all competing cameras (and even some entry level cameras) had a higher pixel count. The Nikon D300 and D90 are both 12.3MP, the Pentax K20D is 14.6MP, the Sony A700 is 12.2MP and the Sony A350 is 14.2MP. Even the Digital Rebel XSi is 12.2MP. While more pixels doesn't always make a better camera, it's nevertheless a number that many camera buyers regard as important and so if you want to sell a camera you'd better make sure it's competitive in terms of pixel count. I'm sure Canon were under significant pressure from their marketing department to leap over the competition and come up with the highest possible pixel count camera consistent with maintaining traditional Canon image quality. What they came up with is the Canon EOS 50D, which at 15.1MP is now the class leader as far as pixels go.
Of course Canon added much more to the Canon EOS 50D than just another 5MP. Improvements over the EOS 40D include:

• A 15.1 MP CMOS sensor with a "gapless microlens" design for higher efficiency
• A 920,000 dot, 3" 640x480 pixel VGA resolution LCD with enhanced anti-reflection coating
• Somewhat improved weather sealing (though still not "weather resistant").
• A microfocus adjustment which can be applied on a fixed or lens by lens basis
• An ISO range from 100-3200, plus expansion to 6400(H1) and 12800(H2)
• An Auto ISO range of 100-1600
• 4 levels of high ISO noise reduction
• 4 levels of auto lighting optimization
• A "creative auto" mode
• Contrast detection AF in Live View mode
• A Face detection mode in Live View mode
• In camera peripheral illumination (vignetting) correction for JPEGs with certain Canon lenses
• HDMI output for playback and display on an external monitor
• A Digic IV processor for faster operation
• Faster USB data transfer
• USMA Support for UDMA enabled CF memory cards

Sounds great, but some reviews have suggested that the noise level of the Canon EOS 50D may be higher than the 40D. I'll look at all that in this review and make some comments on the significance of any differences from the EOS 40D. What really counts of course is the final output, which is usually a print. That's the bottom line for any camera. Lab tests are fine and can provide some useful insight into camera operation, but in the end it's the print that counts.

Canon EOS 50D Brief Specifications

Full Specifications are on the EOS 50D Specifications Page

The rear controls of the EOS 50D are very similar indeed to the 40D. The "direct print" button now has an alternate function which enables Live View and the "Jump" button on the 40D which controlled how you navigated through images during playback is now a "Func" button which can be set to control additional functions such as Live View operation. Otherwise the 40D and 50D seem pretty much identical.

Below the rear LCD (see above) are buttons which control (from left to right), Playback, Erase, Information Display, Picture Style and "Func" which can be programmed for various functions. The Quick Control Dial (QCD) to the right of the rear LCD controls exposure compensation by default and is also used to scroll through menu options. In the center of the QCD is a "SET" button used to confirm and register selected menu options.

The control dials and buttons around the top LCD are identical to those of the EOS 50D. The viewfinder has a diopter control on the right side as shown above. In front of the top LCD are 4 buttons: One for illuminating the LCD, one for selecting white balance and metering mode, one for setting drive and AF options and one for setting ISO and flash exposure compensation. Just below the LCD are three buttons. The rightmost is used to select focus point and magnify the rear LCD display, The center button controls AE and FE lock, playback index and reduces magnification. The leftmost button is for AF start in certain modes such as Live View for example.

The menu functions are also very similar, though on the 50D they are displayed on the new high resolution 640x480 pixel (920,000 dot) 3" LCD. The EOS 40D has a 320x240 pixel (230,000 dot) LCD. Each pixel is 3 dots (one red, one green, one blue). The EOS 50D LCD cover has a new coating which lowers reflections, increases visibility and provides more scratch protection. I'm not going to go through every menu item since that would be pretty dull reading. You can download the EOS 50D manual from the Canon website if you want all the intricate details of control operation. Just follow the "Drivers and Downloads" tab from the EOS 50D page Here. If you have any of the newer EOS bodies, suffice it to say that the EOS 50D will seem quite familiar.

Operational speed of the Canon EOS 50D is fast. It appears to be "instant on", though in reality it probably takes about 1/10s to wake up. Image recording and playback are both fast, despite the larger size of the 15MP image files. In part this is probably due to Canon's new DIGIC IV image processing engine. Even playing back 15MB RAW files takes less than 1/2 second.

Continuous Shooting

Viewfinder

When comparing the noise in images from different cameras you have to be quite careful because just about all cameras apply some sort of digital noise reduction to images shot at high ISO settings. In fact even with all noise reduction functions turned "off", the camera may still apply some default level of noise reduction to JPEG images. Digital noise reduction can sometimes work wonders, but it can smear image detail if too strong - and at really high ISO settings it has to be strong because intrinsic image noise is so high.

The best way to look at the intrinsic image noise is to shoot RAW and make sure that all possible noise reduction functions are turned off (or at least at their minimum setting) before converting the images to JPEG. This is the way the following images from the EOS 40D and 50D were obtained. Note that these are 100% crops from the original images, so on most monitors would represent sections of a very large print, typically somewhere around 24" x 36".

Dynamic Range

Dynamic range is related to image noise because high levels of image noise mean that you lose information in the deep shadows. Dynamic range is basically the range in stops between something that doesn't record as absolutely black (0) to the level that's just below absolutely white (4096 for 14-bit depth). The noisier the shadows are, the more difficult they are to tell from the level you get with no light at all, and so the smaller the dynamic range of the shadows. Using noise reduction has the effect of increasing dynamic range somewhat.

I did not do any scientific measurement of dynamic range, but I did look at the deep shadows in a number of images (using standard noise reduction) and I didn't really see any significant difference between the EOS 40D and the EOS 50D. Perhaps there is a difference which could be measured in the lab, but it was not obvious from real world tests. That's not to say the 40D and the 50D have the same dynamic range, but rather to suggest that any difference that there is probably won't be seen by most users.

Though I didn't do a scientific evaluation of dynamic range, the Dxomark.com website has. DxO is probably the leading company in the digital camera measurement software business and a maker of one of the leading RAW image converters. Their measurements put the DR of the EOS 50D and EOS 40D within less than 1/10 stop of each other, at around 11 stops at the ISO 100 setting and 8.25 stops at the ISO 3200 setting. That would certainly be consistent with my own unscientific observations.

There's no doubt that the EOS 50D outresolves the EOS 40D, just as you would expect it to with the pixel count going from 10MP to 15MP. In theory that would give you about a 22% gain in linear resolution, based on the Nyquist sampling criterion and if all other variables were equal (such as the effect of the anti-aliasing filter, the RAW file demosaicing algorithms and assuming the lens being used didn't limit resolution).

Conclusions

Canon had a difficult job to do with the 50D. As usual, market pressures demanded higher performance, and rightly or wrongly (mostly wrongly), that's often measured by consumers by looking at the pixel count of the sensor. With the EOS 50D Canon have produced the highest pixel count APS-C sensor camera (though the Pentax K20D and Sony A350 are very close), so that should have pleased those who were complaining that the EOS 40D "only" has 10MP, which is now at the low end of the pixel count range for APS-C crop sensor DSLRs.

Of course you can't have everything and increasing the pixel count from 10MP to 15MP means that the pixels have to be 1/3 smaller (22 sq. microns vs. 33 sq. microns), and as we all know, smaller pixels typically mean higher noise levels, especially at high ISO settings. So Canon had their work cut out in trying to make a high pixel count sensor which retained high quality. While perhaps they were limited by the laws of physics from lowering sensor noise, nevertheless I think they did a pretty good job overall. Yes, the intrinsic noise of the sensor (RAW file with no noise reduction applied) is a little higher than that of the 40D sensor, but the resolution is higher too. However, looking a the bigger picture, by applying an appropriate degree of noise reduction (which does tend to reduce detail), the EOS 50D is capable of generating images which have both more detail and the same (or lower) level of observable noise than equivalent images from the EOS 40D.

The EOS 50D adds a number of features to those present on 40D, the most notable of which in my opinion is the microfocus adjustment ability. Given the number of complaints I see in web forums about lenses front and back focusing, this would seem to be a feature many photographers should be willing to give their right arm for, or at least if not their right arm at least a few hundred dollars! Personally I don't have any lenses which exhibit significant front or back focus, but if I did, I'd certainly want the microfocus adjustment ability of the EOS 50D.

The other new features of the EOS 50D such as the 920,000 pixel high resolution LCD and contrast detection focus in Live View are nice to have, though I wouldn't personally regard them as reason to upgrade from a 40D. Then again I don't use LiveView much myself and I don't use the LCD for critical image review.

ISO 6400 and ISO 12800 to the 50D add to the "bells and whistles" count of the EOS 50D. They're certainly nice to have and could be useful at times, but image quality does suffer quite a bit and ISO 12800 is something of an "emergency" setting. If you didn't really have to use it, you probably wouldn't want to. Still, you can't really complain too much about image quality at those ISO levels. Try doing it with film and see what the results look like! The surprising thing is that 4x6 prints at ISO 12800 actually aren't that bad.

The ultimate test of a camera for me is whether I'd want to own it, and I'd want to own the EOS 50D. If Canon came along and said they'd give me an EOS 50D in trade for my EOS 40D, I'd take them up on their offer without another thought. I think the EOS 50D is the better camera for 99+% of the work that I do. The 40D has a very slight advantage in frame rate (6.5 fps vs. 6.3 fps), uses slightly less memory because of the smaller file size and shows slightly lower noise in RAW files. Of course Canon is not likely to offer me a free exchange! I'm less certain that I'd do the trade if it cost me $600, which is about what it would actually cost if I sold my EOS 40D and bought a new EOS 50D. It's an easier decision if you have an EOS 20D or 30D (or even 10D). If I was on that upgrade path, I'd pay the extra $300 or so and go for the EOS 50D.

Right now (mid November), Canon are offering a $100 "Instant rebate" on the 50D, plus many retailers are also discounting their own prices by $100, so that brings the price down from the initial selling price of $1399 to only $1199, which isn't a bad deal. It's even better if you can use an EF 28-135/3.5-5.6IS because if you buy the lens and camera as a $1350 kit you get the lens for $150, which is $250 off the normal retail price.

If you can't afford the EOS 50D, the EOS 40D (which is still a very good camera) is selling for around $850 and if even that is too much, the Rebel XSi with the EF-S 18-55/3.5-5.6IS is selling for only $640, which is a great deal for a starter camera kit.