(Disclaimer - this is not professional or sponsored advice, just a product I've found effective - clean your sensor at your own risk!)
I'm not usually wowed by a product enough to write a blog about it, but I've just used something amazing, which I wish I'd discovered earlier. I have no link to the company or supplier, by the way, I just think this is a great product that every photographer with a DSLR will love (not to be used on Sony sensors though, so not quite everyone)!
I first started cleaning my own camera sensor a few years ago, using pre-made wands wrapped with Pec Pads, with a few drops of Eclipse fluid to do the cleaning. These things were pretty expensive (at least £1 a swab), I ended up needing to use a few, and even then there was always noticeable dust spots at the edges. The plastic wand inside the folded Pec Pad wasn't quite big enough to keep the swab taut, so some dust always escaped the cleaning. I never managed to get all the dust spots, and usually gave up in frustration and removed remaining spots in post-processing. Eclipse fluid is also banned on planes, so if you're going abroad this is easy (and legal) to take with you!
I was running out of sensor swabs recently and started Googling to see where to get replacements (supply and price always seems a bit haphazard). I came across a new product - well, new to me anyway - called the Eyelead Sensor Cleaning Kit, made by a German company that makes all sorts of camera-cleaning products (and sells internationally). I've also seen it called the Eyelead Sensor Dust Sticking Bar Kit. It is a simple piece of kit, a long plastic stick with a cube of solid blue gel at the end of it. The head is protected by a tiny easy-to-open plastic box. Also supplied are 10 pieces of sticky paper. It's not cheap either - I got mine for £31, but having used it now, I know that it'll last quite a while, and it is so much more effective than using the swabs. EDIT Jan 2018 - I bought an additional packet on the cleaning papers on Amazon - prolongs the life of the kit a bit!
It is very easy to use, although it did take me a few goes before I got my sensor clean as I was a little hesitant. Now I know what I'm doing, I can clean it at the first attempt. Make sure you do this is a clean room that hasn't got visible dust in the air!
1. The first step is to make sure the gel cube is clean by pressing it against a clean piece of the sticky paper, remembering to press the edges and corners against the paper too.
2. The next step is to put the camera into "clean manually" mode (that's what it's called on the Canon cameras, anyway). You'll need a full battery, and once you click "OK" the mirror opens up to show the sensor. Take off the lens and you're ready to go. You might want to try a lens blower first to remove any easily dislodged dust or hairs.
3. Using it is simple - just press the little blue cube onto the sensor, a little bit at a time, working your way across and then down and back, making sure you've covered the whole area. I then go around the edges again, making sure I'm getting the gel right at the sides. The corners are easier to get to with a full-frame, larger sensor (I haven't included any photos of me doing this stage, as I don't want to open the mirror again unnecessarily while I faff around trying to get a shot with my other camera!).
4. When you think you're done, turn off the camera and put the lens back on. Then press the dirty gel cube onto a clean piece of the paper (you can reuse the same piece if there's not much dust, as the paper is stickier than the cube). If the sensor was particularly dirty you'll notice quite a lot of dirt coming off (as you can see in the photo on the right below). Once done, replace the plastic protective top over the cube, cover the sticky paper up with its cover (so you can use the clean bits the next time) and put the stick and paper back into the nice little tin for the next time.
5. Before and after I clean my sensor I always take test shots - beforehand to see exactly where the dust is and how bad it is, and afterwards to ensure I've got it all. The settings I use are as follows: ISO 100, aperture mode and as high an f-stop number as the lens has (eg. f/22 on my 24-70mm), and then take an out-of-focus shot of a uniform white wall or ceiling (or the sky). Download and play around with the exposure and contrast to show off any dirt.
6. Also check that your lenses are clean! What might look like dust on a sensor could also be on the lens, either the front or back glass elements. A simple blast of the blower should get rid of most dust. If you're not sure, take a couple of different shots with different lenses and before and after cleaning them too.
EDIT Jan 2018
7. I've always struggled to work out exactly where a dust spot on a photo is on the sensor. I spent far too long trying to dab away at a corner a few months ago, only to realise that I'd misunderstood from someone else's blog where the dust was. Basically it's flipped horizontally. So, if you're looking at the photo and there's a dust spot in the top right hand corner then on the sensor as you look at it from the front of the camera as you're cleaning it, it will be in the bottom right hand corner.
Here are my before and after shots (top and bottom), taken on my Canon 5D Mark III with a 24-70mm lens. The back of the lens was really dusty and produced the large soft splodges, whereas the dust on the sensor led to small darker dots, particularly visible along the right-hand edge. They might look small here, but there were loads, and very irritating to have to clone out in post-processing. As you can see, in the second image (after cleaning both lens with a blower and the sensor with the gel cube) there are almost no dust spots whatsoever.
As I said, it took me a few goes to get the hang of it, finding the right amount of
pressure needed and how to get the gel right to the edge, but once I
mastered it it was easy; I did my Canon 60D in one go straight after
this, removing stubborn dust spots that I'd never quite managed to get
rid of with the fiddly Eclipse-moistened sensor swabs.
Before I did this I watched a couple of really useful videos of other people doing it, so much thanks to them!
Photography Life Video
I will continue to use Pec Pads with Eclipse for cleaning my lenses, but certainly won't be bother with the fiddly swabs again. And now I won't be so afraid to change lenses while away, as I'll be confident that I can clean any dust that creeps in away.