Sensor Cleaning

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Those new to the concept of sensor dust actually hesitate before deciding to clean their camera themselves. Isn't it a better idea to pack up your 40D and send it to a Canon service center so their crack technical staff can do the job for you? Or, at the very least, shouldn't you let the friendly folks at your local camera store do it?

Of course, if you choose to let someone else clean your sensor, they will be using methods that are more or less identical to the techniques you would use yourself. None of these techniques are difficult, and the only difference between their cleaning and your cleaning is that they might have done it dozens or hundreds of times. If you're careful, you can do just as good a job.

Just Trust Bulbous
Figure 9.8 Use a robust air bulb like the Giottos Rocket for cleaning your sensor.

Of course vendors like Canon won't tell you this, but it's not because they don't trust you. It's not that difficult for a real goofball to mess up their camera by hurrying or taking a shortcut. Perhaps the person uses the "Bulb" method of holding the shutter open and a finger slips, allowing the shutter curtain to close on top of a sensor cleaning brush. Or, someone tries to clean the sensor using masking tape, and ends up with goo all over its surface. If Canon recommended any method that's mildly risky, someone would do it wrong, and then the company would face lawsuits from those who'd contend they did it exactly in the way the vendor suggested, so the ruined camera is not their fault. If you visit Canon's website, you'll find this recommendation: "If the image sensor needs cleaning, we recommend having it cleaned at a Canon service center, as it is a very delicate component."

You can see that vendors like Canon tend to be conservative in their recommendations, and, in doing so, make it seem as if sensor cleaning is more daunting and dangerous than it really is. Some vendors recommend only dust-off cleaning, through the use of reasonably gentle blasts of air, while condemning more serious scrubbing with swabs and cleaning fluids. However, these cleaning kits for the exact types of cleaning they recommended against are for sale in Japan only, where, apparently, your average photographer is more dexterous than those of us in the rest of the world. These kits are similar to those used by official repair staff to clean your sensor if you decide to send your camera in for a dust-up.

As I noted, sensors can be affected by dust particles that are much smaller than you might be able to spot visually on the surface of your lens. The filters that cover sensors tend to be fairly hard compared to optical glass. Cleaning the 22.5mm X 15mm sensor in your Canon 40D within the tight confines of the mirror box can call for a steady hand and careful touch. If your sensor's filter becomes scratched through inept cleaning, you can't simply remove it yourself and replace it with a new one.

There are four basic kinds of cleaning processes that can be used to remove dusty and sticky stuff that settles on your dSLR's sensor. All of these must be performed with the shutter locked open. I'll describe these methods and provide instructions for locking the shutter later in this section.

■ Air cleaning. This process involves squirting blasts of air inside your camera with the shutter locked open. This works well for dust that's not clinging stubbornly to your sensor.

■ Brushing. A soft, very fine brush is passed across the surface of the sensor's filter, dislodging mildly persistent dust particles and sweeping them off the imager.

■ Liquid cleaning. A soft swab dipped in a cleaning solution such as ethanol is used to wipe the sensor filter, removing more obstinate particles.

■ Tape cleaning. There are some who get good results by applying a special form of tape to the surface of their sensor. When the tape is peeled off, all the dust goes with it. Supposedly. I'd be remiss if I didn't point out right now that this form of cleaning is somewhat controversial; the other three methods are much more widely accepted. Now that Canon has equipped the front-sensor filter with a special anti-dust coating, I wouldn't chance damaging that coating by using any kind of adhesive tape.

Placing the Shutter in the Locked and Fully Upright Position for Landing

Make sure you're using a fully charged battery or the optional AC Adapter Kit ACK-E2.

1. Remove the lens from the camera and then turn the camera on.

2. Set the EOS 40D to any one of the Creative Zone exposure modes. The shutter cannot be locked open in any of the Basic Zone modes.

3. You'll find the Clean Manually menu choice in the Set-up 2 menu under Sensor Cleaning (see Figure 9.5). Press the Set button.

4. Select OK and press Set again. The mirror will flip up and the shutter will open.

5. Use one of the methods described below to remove dust and grime from your sensor. Be careful not to accidentally switch the power off or open the Compact Flash card or battery compartment doors as you work. If that happens, the shutter may be damaged if it closes onto your cleaning tool.

6. When you're finished, turn the power off, replace your lens, and switch your camera back on.

Air Cleaning

Your first attempts at cleaning your sensor should always involve gentle blasts of air. Many times, you'll be able to dislodge dust spots, which will fall off the sensor and, with luck, out of the mirror box. Attempt one of the other methods only when you've already tried air cleaning and it didn't remove all the dust.

Here are some tips for doing air cleaning:

■ Use a clean, powerful air bulb. Your best bet is bulb cleaners designed for the job, like the Giottos Rocket shown in Figure 9.8. Smaller bulbs, like those air bulbs with a brush attached sometimes sold for lens cleaning or weak nasal aspirators may not provide sufficient air or a strong enough blast to do much good.

■ Hold the EOS 40D upside down. Then look up into the mirror box as you squirt your air blasts, increasing the odds that gravity will help pull the expelled dust downward, away from the sensor. You may have to use some imagination in positioning yourself.

■ Never use air canisters. The propellant inside these cans can permanently coat your sensor if you tilt the can while spraying. It's not worth taking a chance.

■ Avoid air compressors. Super-strong blasts of air are likely to force dust under the sensor filter.

Figure 9.9 A proper brush is required for dusting off your sensor.

Brush Cleaning

If your dust is a little more stubborn and can't be dislodged by air alone, you may want to try a brush, charged with static electricity, which can pick off dust spots by electrical attraction. One good, but expensive, option is the Sensor Brush sold at A cheaper version can be purchased at You need a 16mm version, like the one shown in Figure 9.9, which can be stroked across the short dimension of your 40D's sensor.

Ordinary artist's brushes are much too coarse and stiff and have fibers that are tangled or can come loose and settle on your sensor. A good sensor brush's fibers are resilient and described as "thinner than a human hair." Moreover, the brush has a wooden handle that reduces the risk of static sparks. Check out my Digital SLR Pro Secrets book if you want to make a sensor brush (or sensor swabs) yourself.

Brush cleaning is done with a dry brush by gently swiping the surface of the sensor filter with the tip. The dust particles are attracted to the brush particles and cling to them. You should clean the brush with compressed air before and after each use, and store it in an appropriate air-tight container between applications to keep it clean and dust-free. Although these special brushes are expensive, one should last you a long time.

Liquid Cleaning

Unfortunately, you'll often encounter really stubborn dust spots that can't be removed with a blast of air or flick of a brush. These spots may be combined with some grease or a liquid that causes them to stick to the sensor filter's surface. In such cases, liquid cleaning with a swab may be necessary. During my first clumsy attempts to clean my own sensor, I accidentally got my blower bulb tip too close to the sensor, and some sort of deposit from the tip of the bulb ended up on the sensor. I panicked until I discovered that liquid cleaning did a good job of removing whatever it was that took up residence on my sensor.

You can make your own swabs out of pieces of plastic (some use fast food restaurant knives, with the tip cut at an angle to the proper size) covered with a soft cloth or Pec-Pad, as shown in Figures 9.10 and 9.11. However, if you've got the bucks to spend, you can't go wrong with good-quality commercial sensor cleaning swabs, such as those sold by Photographic Solutions, Inc. (

Figure 9.10

You can make your own sensor swab from a plastic knife that's been truncated.

Figure 9.10

You can make your own sensor swab from a plastic knife that's been truncated.

Figure 9.11

Carefully wrap a Pec-Pad around the swab.

Figure 9.11

Carefully wrap a Pec-Pad around the swab.

You want a sturdy swab that won't bend or break so you can apply gentle pressure to the swab as you wipe the sensor surface. Use the swab with methanol (as pure as you can get it, particularly medical grade; other ingredients can leave a residue), or the Eclipse solution also sold by Photographic Solutions. Eclipse (see Figure 9.12) is actually quite a bit purer than even medical-grade methanol. A couple drops of solution should be enough, unless you have a spot that's extremely difficult to remove. In that case, you may need to use extra solution on the swab to help "soak" the dirt off.

Once you overcome your nervousness at touching your 40D's sensor, the process is easy. You'll wipe continuously with the swab in one direction, then flip it over and wipe in the other direction. Figure 9.13 shows a swab being lowered past the lens mount down to the sensor. You need to completely wipe the entire surface; otherwise, you may end up depositing the dust you collect at the far end of your stroke. Wipe; don't rub.

Figure 9.12 Pure Eclipse solution Figure 9.13 Carefully swab off the dust.

makes the best sensor cleaning liquid.

Figure 9.12 Pure Eclipse solution Figure 9.13 Carefully swab off the dust.

makes the best sensor cleaning liquid.

Tape Cleaning

There are people who absolutely swear by the tape method of sensor cleaning. The concept seems totally wacky, and I have never tried it personally, so I can't say with certainty that it either does or does not work. In the interest of completeness, I'm including it here. I can't give you a recommendation, so if you have problems, please don't blame me. The EOS 40D is still too new to have generated any reports of users accidentally damaging the anti-dust coating on the sensor filter using this method.

Tape cleaning works by applying a layer of Scotch Brand Magic Tape to the sensor. This is a minimally sticky tape that some of the tape cleaning proponents claim contains no adhesive. I did check this out with 3M, and can say that Magic Tape certainly does contain an adhesive. The question is whether the adhesive comes off when you peel back the tape, taking any dust spots on your sensor with it. The folks who love this method claim there is no residue. There have been reports from those who don't like the method that residue is left behind. This is all anecdotal evidence, so you're pretty much on your own in making the decision whether to try out the tape cleaning method.

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