Digital SLR Cleaning Methods
Sensor Cleaning Strategy
In most modern DSLR’s the sensor is fitted with anti Anti-Aliasing filter directly in front of it. Often called a low-pass filter, the AA filter is designed to reduce the effects of moiré patterning, which can occur when taking images of regular structured surfaces such as fabrics. The low pass filter may also incorporate Ultra Violet and Infra Red Filtration to control the light passing through to the sensor. It is the Low Pass filter that contamination settles on and which we need to clean. So, strictly speaking, it should be called Filter Cleaning rather than Sensor Cleaning, however the term Sensor Cleaning is usually used, even if the sensor does not actually get cleaned.
The Low Pass Filer sits directly on top of the Sensor, but is not necessarily sealed around the edge. Caution should be applied when using a liquid cleaner to ensure that the liquid does not migrate between the two surfaces of the filter and the sensor, where it will impossible to remove without expert help.
Contamination can arise for a number of reasons, Dust particles, pollen, wear and tear and so on. For cleaning purposes, we should consider two types of contamination and deal with them separately. There are loose dust particles, which can be cleaned off the sensor in a number of ways, and then there are the more stubborn ‘stuck-on’ or greasy marks that are harder to remove. A sensible cleaning strategy will clean away loose dust particles first, then deal with the stuck-on marks separately. Cleaning away stubborn marks effectively will require the sensor to be wiped with some form of cleaning swab and cleaning solution. Wiping the sensor does introduce a small risk of dragging an aggressive (hard) dust particle across the sensor surface and causing a scratch. However, if the loose dust particles have been properly removed prior to wiping, then the risk of scratching is eliminated.
Clean the loose dust from the sensor first.
Then wipe away the greasy marks second.
The longer loose dust is left on the sensor, the greater chance it has of becoming hard to remove. Particularly if the camera goes through a few humidity cycles. For example, when it’s left in car overnight and gets very cold, and is then brought into a warm environment. Sensor dust will get damp from the humidity, then dry out and stick to the surface.
If proper attention is paid to cleaning away dry, loose dust on a regular basis, then the need to swab the sensor is greatly reduced.
If you have taken your camera onto a beach, and you think there is sand inside it, please take it to a professional repair organisation to be cleaned. Sand is a most aggressive material and one particle can severely scratch the sensor. If you must take your camera onto a beach, ensure it is kept in a sand-proof bag and return the camera to the bag immediately after use. If you need to change the lens on a beach, use some form of protection such as CameraBivvy to minimise the opportunity for sand to enter the camera.
So, now we know what strategy we are going to use, lets examine the various cleaning techniques available to today and consider their advantages and disadvantages.