Unfortunately they do more of a job of “hiding” dust than they do removing it. An expensive investment in a camera like the 5D (Canon EOS) can really hit the pocketbook. It would seem like a shame not to take good care of it like the high precision instrument that it is.
Digital camera cleaning of parts, like the lens and body are relatively easy compared to the delicate task of cleaning camera sensors. This is why extreme care should be taken at anytime you remove the lens from your camera body. A damaged sensor would be a costly repair considering some of the middle end models of d-SLR come in at around $2,000 to $3000. Even if you only purchased a “pro-sumer” model like a Canon Rebel XTi or a Nikon D40 for around $800 or $900. It’s probably a sizable investment for you so the best advice is just to be careful.
It is highly recommended that you avoid the use of canned compressed air, especially if you are inexperienced. There are chemicals involved that could damage the sensor if expelled into the camera. In the past, with film SLRs it was perfectly acceptable to use the compressed air as the internal nature of the camera was not as delicate. While there are propellant free compressed products available, I just as soon avoid them myself. I hate to beat a dead horse but since you spent so much money on your camera, you should treat it as you would any expensive investment. While blowing air into the camera housing is quick and easy, it’s not always the best solution and of course, as I have mentioned can be dangerous. Just avoiding compressed air all together would be my advice.
If you must use a product like this due to time constraints, etc. You should go with a CO2 and nitrogen cartridge based systems that are moisture free but can be very expensive.
There are many products on the market that I recommend and that I myself use. One can obtain digital camera cleaning products anywhere that sells cameras or optical equipment. However, one must be prudent since we are dealing with a large investment of money and don’t want to risk damaging our camera just to save a few dollars on cleaning supplies. There are camera dealers that I myself have been to that recommend products that I would never use on my camera. It’s not their fault. Generally they want to be helpful but are most often working for a large corporation and are hourly employees that, while well-meaning, don’t have the experience to dictate how you should handle your $3000 camera.
I talked briefly about automatic dust removal systems. While these will help you out of a situation where you get dust in your sensor and don’t have the ability to clean it right then and there, these will work fine. The methods used by the camera are things like vibrating the sensor to “kick” off dust, having a static charge around the sensor to attract dust away and in severe cases, the camera will electronically remove dust from the image itself. This works with a sophisticated algorithm inside the electronic brain of the camera that “detects” dust and uses neighboring pixels to fill in those areas. However, before every major shoot that is important to me and of course, my client, I use the following techniques.