Hands on: Keep your camera sensor speck-free

Scrub it off
For those stubborn, hard-to-remove particles, you’ll need something more aggressive than a puff of air, but obviously you don’t want to run the risk of causing any damage.

You wouldn’t expect to find too many companies prepared to guarantee that their products won’t damage your sensor, but one such is Photographic Solutions. Its Sensor Swabs are recommended by Kodak, Fujifilm and Leica.

The swab is a sensor-sized spatula (they are specifically designed for different camera models), manufactured in a clean room with a lint-free tissue pad covering the end.

You apply a couple of drops of Eclipse fluid, a methanol-based residue-free cleaning solution, to the end of the swab and wipe it across the sensor first using one side of the swab, then the other.

My first effort with Sensor Swabs resulted in little improvement, with my test image revealing about the same level of contamination as was present prior to cleaning. I repeated the process with a second clean swab, and this time things got worse.

In addition to the familiar light-grey, slightly translucent dust spots, a horrible black mark had also appeared. Had I scratched the sensor? There was nothing for it but to try again. This time I only used one side of the swab, sweeping the sensor from left to right, and things started to improve.

Many of the dust spots were gone, but the worrying black mark was still there. A fourth single-stroke swab did the trick, removing the black mark and the remaining dust spots.

I got my Sensor Swabs and Eclipse solution from Warehouse Express. At £35.95 for a pack of 12, plus £7.99 for the Eclipse fluid, it’s not a cheap solution (pun intended this time, sorry), but it works and, from my experience at least, appears to be safe.

Send it off
At this point it’s worth mentioning that attempting to clean your camera’s sensor could invalidate the warranty.

The blower method is the one recommended by Canon and, if you carry it out according to the instructions in the manual, you shouldn’t have anything to worry about.

Whatever the manufacturer and model of your camera, if the worst should happen and you damage the sensor, the most likely outcome is that you’ll be faced with a hefty repair bill.

If the prospect of poking about with swabs and blower brushes fills you with dread, but you still want to get rid of the dust, you should contact the manufacturer’s service department and ask them to do it for you. It won’t be cheap, but at least you don’t have the worry of ending up with a bigger problem than you started with.

Software solutions
If all else fails, or the dust spots are already on your images and it’s too late to do anything about it, you can always retouch them out. Don’t worry if your retouching skills are a little rusty, or even non-existent, there are automatic tools that will do the job and manual retouching of dust spots is not all that demanding.

Canon’s Digital Photo Professional application, which ships with most Canon digital SLRs, includes the same Fare (Film Automatic Retouching and Enhancement) technology used in Canon’s flatbed scanners. Fare automatically retouches dust spots and other marks and blemishes.

Nikon’s Capture 4 Raw image-processing application uses a reference image to identify and map the location of dust spots on the sensor and then automatically retouches them out.

Retouching
For light dust contamination – just the odd spot here and there – I’ve found that manual retouching is the most effective solution. Even if you have a lot of images you won’t need to retouch them all and, once you’ve done one, you’ll know exactly where to look.

You can do this in any image-editing application that has a clone tool.

Layer support is also useful. I will briefly describe how I do it in Photoshop, but you should not have any problem adapting the technique if you use another application.

Start by creating a new layer and calling it ‘retouch’. Select the Clone tool and pick a brush that is about twice the size of the dust spots with a very soft edge – in Photoshop use 0% hardness.

Check the Aligned and ‘Sample All Layers’ boxes in the tool options bar. This ensures that the pixels from the background layer are copied into the retouching layer. If your image editor can’t do this, just copy the background layer to create the retouching layer.

Sample an area close to the dust spot that is similar in tone and colour. For skies this will usually be to the right or left of the spot rather than above or below it. Then just click the spot to remove it. If there is a visible mark where you have cloned, choose Undo, resample from a different area and try again.

Most of the time it will work first time. For troublesome spots you may need to alter the brush size and hardness, sample a different area or alter the opacity. Changing the blend mode to lighten can also be helpful. If things really get messed up because the cloning is on a separate layer, it is easy to erase and start again.

Dust dos and don’ts
1. Prevent dust entering the camera. Use (clean) lens back caps and camera body caps, and keep the time the lens is off the camera to a minimum.

2. Switch off the camera before changing lenses (some cameras automatically switch off the sensor when you remove the lens).

3. Hold the camera with the sensor facing downwards when changing lenses.

4. Send your camera to the manufacturer to be cleaned professionally if you don’t feel confident about doing it yourself.

5. Don’t put body caps and lens caps in your pocket.

6. Don’t use a blower brush to brush dust off the sensor.

7. Don’t use compressed air products to blow dust off the sensor. The propellant leaves a residue which will smear the sensor and gunk up your camera.

8. Don’t insert a blower into the body. If the battery fails, the shutter and mirror will close on it, probably causing expensive-to-repair damage.

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