Time is precious and I dont really want to spend time trekking to the Canon service center and then waiting 30 mins for the CMOS of my DSLR to be cleaned.
I read in the manual that I shouldn't attempt to clean it myself and every time I opened the shutter to blow dust away from the CMOS I would break out in a sweat knowing how delicate the sensor was. Usually a blower does the job but eventually you'll end up with some scum dust on the sensor that just does not want to go anywhere. Leaving the dust there means that you will get blobs on your photos. Have a look at this photo - notice the annoying blob in the sky.
I searched to see if there was a way for me to clean the CMOS myself and chanced upon two sites - one in English and the other in Japanese. The Japanese blog advised to get some lens cleaning paper, cleaning liquid and sharp cleaning buds which I got from HCL - folks in Japan can order directly from them.
Cut some of the cardboard from the lens cleaning liquid package and then wrapped some of the cleaning paper around it. Gave the paper a few drops of cleaning liquid and took a deep breath. Too little liquid and you may scratch the surface of the CMOS. Too much liquid and you may leave liquid marks on the sensor which will show up in your photos.
Make sure you have good lighting before you start and proceed to wipe the sensor. Not easy but you'll feel satisfied after when you manage to pull this off. When the sensor looks clean, take a picture of a monotone surface - and make sure the picture is in focus. You should check the photo on a computer screen as its difficult to spot blobs on the SLR built in LCD. You'll probably have to repeat this process a few times.
There are many ways that dust gets into the chamber where the CMOS is. To decrease the chance of dust getting on the sensor, make sure the lens and lens attachment parts are clean. For this I use some of those pointy buds dipped in cleaning liquid. Not sure how to prevent mechanical dust though.
Taken before cleaning. Adjusted the curves in Fireworks so that you can see how bad the situation was. Whenever I have a photo session, I would always take a picture of the sky to check for blobs.
If you are going to clean the CMOS yourself, please do so at your own risk! I would say that if you can make Gundam models then you are good with your hands (oo er) so you'll probably be able to pull this off - but then again, you decide ^^;