Many photographers I know were both enthused and disrupted when Canon recently announced its new category of camera, the EOS 7D. It was a particularly distressing announcement for the many Canon shooters who for several years have been trying to make a final decision on whether to dedicate their style to the APS size sensor camera models or to become a 5D and 1Ds studio, accepting no less than full frame sensor imaging. Many Nikon shooters went through the same angst over the past year, with choices such as the D3x and the D300 and D700 series.
Naturally, many photographers will own and continue to own a variety of both APS-size sensor models as well as full frame cameras, thereby having the tools to properly shoot their assignments with whatever is best for that job. Some shooters I know buy every single new DSLR that their system of choice comes out with. One problem with that is that each camera model produces images with a slightly different look. But that's another story.
The real question is, when do you have either enough cameras in your arsenal or when do you stop upgrading bodies and quit losing money on exchanges? Those who have been in the business since the 100% film days remember that this was not a problem then. Camera models were good for years, especially medium format models, and companies like Canon and Nikon only made occasional, incremental improvements to their flagship professional cameras.
You could always count on the lenses being good for an amazing number of years. Today, thankfully, your investments in glass will still last a long, long time, but even lens technology is now moving at an accelerated pace. Although your 70-200mm f2.8 IS lens will create superb images for the foreseeable future, an improved model is sure to come out within a few years, or the technology will develop to produce an f2.0 model without significant changes in weight and size. What is not lost on the manufacturers, however, is the fact that today's photographers will accept larger and heavier cameras and lenses in order to have the technology and quality, a trend contrary to that of the late 70's and 80's, which was then moving toward smaller bodies and lenses.
The decision whether to buy or not buy a new camera body model should be strictly based on business need, business upgrade, or new opportunities. Any piece of equipment you buy should be justified by the profit potential it offers your business, as compared to not buying it. A new model may have worthy new features, like HD video recording, that may help you develop either a new product, or a competitive edge.
For comparison of situations I will use the new 7D as an example. The camera is equipped with an APS size sensor, but comes with 18 megapixels in a new technology which Canon claims will give the sensor lenses more tonal range. So, although it had seemed that APS megapixels had maxed out at around 15, this new sensor is supposed to address the crowding issue. The camera offers 1920 x 1080 full HD video at 30 FPS. While no one expects this to produce the spectacular video results of the 5D Mark II, it promises to create a reasonably close and superior product. The real question is, can your business benefit from the video capability of the camera.
The next question is whether you were in the market for a new camera body already? If you were seriously considering picking up a 50D, I would say that the 7D is a no-brainer, even though you will spend about $500-$700 more after the 50D discounts, which are already being applied.
If you were not in the market, the answer is not so clear. Again, will the 7D somehow help you in developing a greater profit margin? Will you sell an older camera model or keep it as a back up? If you sell, the "trade-in value" can be applied to your purchase, at least on paper. Are your old cameras ready to go? One hears amazing stories about older models like the 20D and the D70 having gone through an amazing number of shutter clicks. The number of shutter clicks was never specified for older models, but many have exceeded expectations and even more after replacing the shutters. So, is it worth it to toss your 40D yet? Maybe ... maybe not.