Let’s go back in time, to the dawn of the DSLR age, which to be honest, really wasn’t that long ago. As more and more people started to adopt DSLRs, a common problem started to occur and with it some well propagated myths. The problem was sensor dust. The myths included that you could not clean the sensor yourself and that if you tried, there was a possibility that you will damage the sensor. Many of these myths were spread by camera manufacturers and repair companies who tried to create a cottage industry out of sensor cleaning. Over the last few years, it has become apparent that it is indeed quite possible to clean your own sensor. It has also become apparent that it is, in fact quite difficult to damage sensors. The reason for this is that most, not all, DSLR sensors have what is know as a lowpass filter. This sits over the sensor. Made of glass, this filter, is in fact pretty tough. The biggest issue that you are most likely to face is smears, not scratches.
Why Sensors get Dirty
So let’s first have a look at why your sensor gets dirty and how to determine if it needs cleaning. Whilst on stills you can always clean images in post production, it is a lot more difficult with video footage. Every time your remove a lens from your camera you are increasing the likelihood of dust entering the mirror box. In fact, even if you never remove the lens you can still get dust. This is because as you turn a lens’s focus or zoom you can create a mild vacuum that sucks dust in. Now many cameras today have anti dust mechanisms such as vibrating the sensor. These can be very effective but they are not infallible. Some dust has an adhesive quality that literally sticks it to the sensor making it very difficult to remove.
Do I Have Sensor Dust?
The easiest way to determine if your camera is suffering from sensor dust is to take a picture, at a small aperture, of a white wall. Defocus the camera as this will eliminate any blemishes that might be on the wall. Load the resultant image into your computer and examine it at 100% view all over. Dust will easily show up as small dark specs on the image.
So having determined that we have a dust issue, how do we go about removing it? Well these days there are a multitude of options falling into two broad areas, dry clean and wet clean. You should always attempt dry cleans first, a dry clean means that you do not need to come into contact with the sensor with any cleaning fluids.
Dry Cleaning a Sensor
The first dry clean stage is to use a hand blower. If your blower comes with a brush, remove it and before blowing the sensor. Give the blower several blasts to clear any dust that may be in it’s nozzle. Next, put your DSLR in bulb or cleaning mode, remove the lens with the camera facing down. Activate the shutter and give several blasts of air, aiming if possible from the center of the sensor towards the edges. For loose dust, a simple blast from a blower will remove most dust bunnies. Never use condensed air for this, the chemicals in the propellant can cause damage to the sensor.
Another example of dry cleaning is to use a static brush, for example the Arctic Butterfly. These brushes use a static electrical charge to attract the dust off the sensor and onto the brushes’ bristles. Some people swear by these brushes, others have had mixed results.
Dry Cleaning with Sensor Pens
Another recent addition to the sensor cleaner’s armory is the sensor pen. This is an adaptation of the popular lens pen and uses a triangular soft pad at the end of a pen. This is applied gently to the surface of the sensor, moving from the center to the edges. It is best used in conjunction with a sensor loupe. This magnifies the sensor area so that you can see if there are any large dust particles on the sensor. As this is a contact cleaning technique, you need to be confident yet gentle when using the sensor pen. Another useful technique is to use specially designed vacuum kits such as the Green Clean Mini Vac. These literally suck the dust from the sensor.
Wet Cleaning a Sensor
Whilst most of the above dry cleaning techniques are good for loose dust, at some point or another, you will find a dust spot that adheres itself to the sensor and cannot be removed. In this case it’s time for a wet cleaning. Wet cleaning, as it’s name suggests involves using a specially formulated solution on the sensor to remove stubborn spots. The major downside to this, especially for first timers is that you have to make several contacts with the sensor, first to apply the fluid and clean, secondly to remove the fluid. As mentioned at the top, most sensors are in fact covered with a glass, lowpass filter, and it is actually this that you are cleaning but you still need to apply care and attention. The most common form of wet cleaning is by using specially designed pads in combination with an alcohol based fluid. The best know of these is Sensor Swab and Eclipse Cleaning Fluids. You will need several Sensor Swabs, making sure that you have the right size for your sensor.
Using Pec Pads and Eclipse Fluid
Apply one drop of Eclipse fluid to the swab and gently wipe across the sensor in one direction. Now take a dry swab and repeat in the same direction, then take a shot to check for further dust. Wet cleaning will often require several attempts to remove all the dust, the major issue with this being the price of the swabs. It is possible, for the more adventurous, to create your own swabs from lint free lens cleaning paper or Pec Pads and a plastic spatula, you can even attempt to put the Pec Pad over an old Sensor Swab stick, this can save considerable money for those of you prone to dirty sensors.
The reality of sensor cleaning is that there is no one single way to go about it. Start with the basic dry techniques and if you find you have some stubborn marks move onto the wet technique. Before starting make sure you either have a fully charged battery or AC power supply to prevent your shutter closing mid clean. Be confident yet gentle and thorough. Lastly if you do not feel confident, there are many places now that will do a sensor clean for you. These are not usually cheap but they will give your the piece of mind that the cleaning is being done well.