The new 40d is a spectacular camera, most likely the best DSLR for the money ever produced by any company.  When it comes to features and ease of use, the new technology in the 40d is a great step forward.  When it comes to image quality, in many respects the 40d may very well be the equal of the 5d.  Currently there is some discussion in various places on the internet about this, with many claiming without qualifications the IQ (image quality) of the 40d is equal to that of a 5d.  But that’s the rub ... it depends on how you define it.

Typically when reviewing a camera, writers focus on how it improves over it’s predecessor.  Indeed that was my main interest - how does the 40d compare to the 30d?  When you bring the 5d into the equation, you really change the parameters of the comparison ... it isn’t apples to apples anymore.   The reason is pretty simple ... when you are deciding between two cameras of different resolutions and sensor sizes, resolution is sometimes a major or even primary concern.  

So to define the parameters of this discussion, let me say right now it is about IQ relating to pure resolution alone, and not any other aspect of IQ.   (In fact, in a follow-up article you can read my opinion that except for the resolution differences, the 40d equals or exceeds the 5d in all other aspects of IQ).

Before getting to the tests, a little discussion about my perspective may provide some insight as to where I’m coming from.  It may also help those trying to decide in clarifying their own needs.  If you want to cut straight to the chase, no problem, just scroll down to the section SO IS THERE A DIFFERENCE?

To begin, let me pose two questions. How much better (if any) is the resolution of a 5D over  the 40d - is it enough to ever make a difference?  If so, then the second question - how often (if ever) will that additional resolution be a benefit to what you do as a photographer?

Let me start with the second question first, because it is a question that predates digital cameras by several decades , and applies when purchasing any camera.  I used a Hasselblad to do weddings early in my career, even though a good 35mm would have been more than enough resolution to print the 4x5’s, 5x7’s, and 8x10’s most of these images were destined to become.  But I couldn’t risk not being able to sell 16x20’s, 20x24’s,  or larger prints because of the limited resolution of the 35mm.  I chose a higher resolution medium format camera because I might need it(which as it turns out I often did), not because I knew I needed it.  I also used a Mamiya RZ67 for portrait work.  When purchasing the Mamiya, I knew that most of the time I didn’t need the resolution (nothing wrong with a Hasselblad), but I also felt there would be some occasions where that 6x7 negative would capture important detail that might elude even the Hasselblad - a graduation class picture of 200 students for example.  So I used the Mamiya for portrait work, fully knowing that I wouldn’t need it’s resolution most of the time.

There is no “right” answer to this question ... each photographer has different needs, shoot different types of photography, and have different output needs. If all you ever print are 5x7’s and 8x10’s, you probably don’t even need a 40d.  In the digital era, budget constraints often answer the question - you get whatever resolution the camera has that you can afford. Those interested in maximum detail and resolution would most likely choose the new 1DsMark3 if it was in their budget rather than either of these two cameras.  It’s also quite possible to reach a level of resolution that meets or exceeds all a photographer does or intends to do, so future upgrades become less meaningful.  At my company, Kiddie Kandids, after migrating from Kodak 520DCS (with a maximum print size of 11x14), to Kodak 560DCS, to Kodak 14n to the Canon 20d (where we now will print up to 24x30’s, we reached a point where more resolution really isn’t an important factor.  99% of our subjects are of a single child, or perhaps of a group of two or three.  We can resolve eyes, lips, and even hair texture just fine.

I’m not sure everyone fits that nicely into a little package, and even though most of what everyone captures probably doesn’t have significant detail, I’m sure at least some images from most might benefit from a little more detail.

One other consideration is the lenses you use and the type of work you shoot.   While it is true the 5d has more overall potential resolution, if you shoot mostly telephoto work, and in fact would most often crop a 5d image to get the composition you want, in effect you gain nothing, and in fact lose that additional resolution.  The APS sensor of the 40d will yield greater resolution than the same physical area  of the 5D sensor.  Sports and wildlife photographers come to mind as two areas where this would apply.

Winter’s Arrival

Canon 40d with 400mm f/4 DO IS USM, 1/100th at f/14.0, ISO 400

Moving on to the second question, it reminds me of when the 5d was introduced, and there were similar statements made about image quality - the 12.8mp 5d was equal and perhaps better than the 16.7mp 1Ds Mark2.  They didn’t seem to be qualified either, so simple extrapolation now implies that a 10mp camera has matched a 16mp camera in all aspects of IQ.  Really? Even resolution?

There is no doubt as cameras and sensors get better, they may close the gap with a higher resolution sensor.  And let me be perfectly clear ... there is a lot more to it than megapixels alone.  My new G9 is 12mp, but in no way is it equal or even close to a 40d.  But we’re talking about 2 very good sensors here, one a little older but with more and very large sensor sites, the other newer, but with fewer and much smaller sensors. I’m not an engineer, but logic tells me  if all other factors such as noise are nearly  equal, there is still the simple fact that a pixel is a pixel, and if detail gets smaller than the pixel on the chip, the chip can’t resolve it.  When comparing the 40d and 5d, we’re talking about 30% more pixels recording the same information.

SO IS THERE A DIFFERENCE?

I decided to try and do what I call real world tests.  Take the two cameras outside, and take pictures of scenes that I knew would push the resolution of both of them ... scenes with a lot of very small detail.  I used the lenses I would normally use - they are very good lenses, and I’m not sure I would give them up for the sake of a different body.

Take a look and then if you want, come back and read some of my conclusions - 5d vs 40d test page

From what I’ve seen so far, (and I’ve done this about 10 times now), the 5d is capable of capturing finer detail than a 40d.  The scene I use has extremely fine detail, and I’ll be honest, even the 5d can’t capture all the subtle textures and details available in the pine trees.  In fact, to me those textures area critical component of many of my landscape images, and provide some very subtle depth and clarity to a big print.

So at this point in time, I still believe the 5d can capture very fine detail (a nice term I’ve heard used for this is micro-detail) a little better than a 40d.  I really cannot say that it is worth the additional cost, except to those photographers who are trying to capture the maximum detail in their images and are printing it quite large.  Other than that the decision is really more about the difference between a full frame sensor, or the 1.6 crop factor of the APS size sensor, as well as other features of the camera including speed, cost, available pop-up flash, etc.  For most it really is more about personal preferences, and there are plenty of articles and discussions about that on the web.

As I see it, if detail alone is your primary consideration, and you are a landscape photographer or a portrait photographer doing family groups, the 5D seems to win.  If you are a wildlife photographer or a sports photographer, the 40d seems an obvious best choice because you probably end up cropping the 5d images anyway, negating the extra resolution.  If you tend to do a lot of weddings, you may want to research the highlight priority mode of the 40d ... it may be very helpful in dealing with that white wedding dress.

I personally know with the kind of images I take (landscape) I usually go with the camera that can capture the most detail that I can carry, and the 5d fits in as my 3rd choice in the pecking order.