I would consider myself a semi-pro when it comes to photography. I've spent the last three years using the 5D and have finally worked up enough business, to where it's time that I purchase a backup camera. The 40D is an obvious choice. I had previously shot with the 10D a few times, but not often enough to write a comprehensive comparison. I will say the 40D is light-years above that model, as can be expected. For this review I will occasionally compare it to the 5D, as that has been my primary camera used.

When it comes to weight and size, I've found the 40D to be about perfect. The textured grip holds well in the hand, and it's easy to adjust the shutter speed and aperture with minimal finger movement. One of my biggest complaints with Nikon is how they put the aperture dial on the front by the finger. When shooting Nikon, I almost always would hit it accidently. Canons decision to place it on the back by the thumb is perfect. And if still worried about hitting it, it's easy to click the power switch and turn that particular dial off.

In regards to buttons and dials: Canon has stayed consistent with the top buttons near the LCD and how they function. I've always felt these were easy to figure out and well laid out. Hit the appropriate top button, and what's being adjusted is easy to view on the top LCD. The top left of the camera has a dial that can be used to change shooting modes; auto, shutter priority, manual, and some pre-programmed options for beginning users. Personally, I always leave it on manual or one of the priority modes. I can't speak of how well the pre-programmed options work. I will say, that I somehow manage to hit this dial and change the shooting mode. I' m not sure how I always do it, but one minute it's good, and the next I notice that it's moved to something else. It's my only complaint about the camera, and obviously my own fault. It would be nice if I could turn this off instead of the aperture wheel. The camera also allows for custom functions, but I haven't tried setting any of these, so couldn't tell you how easy or not it is.

The live view function is one of those features that I thought I would never use, but have actually found pretty useful. This is quick and easy to engage and disengage. What it does, is allows the user to view the image using the LCD on the back of the camera, instead of peering through the viewfinder. I've found myself using this when I have the camera on a tripod for still life and other product style shoots.

The camera does use the smaller sensor common on most DSLR cameras. This has been the most drastically noticeable difference for me. Having become accustomed to the full framed sensor, I find myself constantly re-adjusting where I'm standing to account for the multiplication factor. For anyone who doesn't know what I'm talking about, do a Google search on full frame camera sensors. No need to go into an explanation here.

The camera has a sensor shake option for dust reduction. One of my biggest complaints about the 5D is how easily dust gets on the sensor. The 40D does a much better job of sealing the camera overall, and having the sensor shake helps me go that much longer in between sensor cleanings.

The camera does come with a little pop-up flash. I haven't used this too much. For the most part, I have a separate flash that I attach to the camera, but there have been a few times out, that I didn't bring it, and found having this on the camera as a backup to be very helpful.

One thing Canon did with this model is move the menu buttons below the LCD. I've read this had to do with real estate on the back of the camera. Personally I've found this very difficult to get used to. Especially since I go back and forth between two cameras. Since it's all one manufacturer I'd like to see more consistency. Although, I have a feeling the new 5D will mirror this new layout.

Upon going into the menu they also changed the layout here is well. Instead of one screen that scrolls up and down on the 5D, you can scroll through multiple menus. I'm impartial on this change, and can see the advantage to it.

The camera burst rate offers "6.5 fps, up to 75 consecutive JPEGs or 17 RAW images". For me, this is plenty. I have found with my shoots that this has easily met my needs, and to my understating is a jump over previous models. I can say, it's a heck of a lot faster than the 5D.

The back LCD is large and easy to view. As with all digital cameras it's practically impossible to review images in bright daylight. My response to people who complain about this is, if you are a good enough photographer, you shouldn't need to look at every picture you take right after you take it.

Would I choose it over the 5D? No way! But, overall I've been very impressed with the 40D, and I’ve found it to be a less costly backup to my existing system. Since the lenses are all compatible, I don't need to purchase new glass for switching back and forth. I also find myself looking forward to some of the features that the 40D has and that will be available on the 5D Mark 2.