I'd taken a few photos of the setting sun the other night, when reviewing the images I noticed a few little splodges over them, at first it looked like someone had sneezed on my monitor. A bit more closer investigation revealed that the flaws were with the original images. At this point I realised something was wrong with my camera. After checking the lens I realised that the cameras sensor (the actual part that records the light to create the image) had got dirty (most probably bits of dust, pollen and similar).
This is one of the pictures I took, about a 1 second exposure at F29.
This is the same picture after I quickly looked and circled the flaws in The Gimp, they are much more noticeable on the original (unscaled) picture.
Anyhow, this caused me a bit of concern as I've heard before about how Digital SLR's will need the sensor cleaning sooner or later, I've had the camera nearly 2 years now so it was probably about time it needed cleaning.
To check the extent of the problem I pointed the camera at a plain surface (in this case a wall painted with magnolia) and put it to one of the highest F stops in Av mode and took an exposure. (for extra effect make sure that the lens isn't focused and move the camera around the subject area to make sure the picture comes out blurred)
After a bit of googling later, I came up with a few solutions, the best one I could see was to buy a starter set from Warehouse Express who are a good local (to me) company who sells lots of expensive things that I want to own and can't afford. I ordered a "Introductory Cleaning Kit" for about 20 quid which comes with some "sensor swabs" and a small started bottle of "Eclipse cleaning fluid" as I didn't want to order a whole pile of the stuff as it is quite expensive.
This is the before picture, that I took to check the extent of the problem. I messed around with the colour levels using the Gimp to enhance the flaws, notice all the little black dots!
And after cleaning! There are a few spots still but I don't think it is worth bothering about them as they are now only around the edges, and I don't want to try and clean it too much.
The actual method I used to clean the sensor was to put the camera in "sensor clean" mode, and then put a couple of drops of eclipse cleaning fluid on the sensor swab and wipe it over the sensor once from left to right and then put a lens back on the camera and took a test photo to see if any more dots appeared.