It is sometimes wrongly thought that the spots that appear on photos come from the mirror, optical viewfinder or lens, but this is often not the case. Dust on the mirror or the viewfinder does not have any effect on the final rendering of the photo. As for dust on the lens, this will be too far from the focal point to be sharply focussed. This may occasionally happen with a fish-eye lens, but hardly ever with a standard lens.
Generally, it is the dust that has infiltrated inside the camera body and has settled on the sensor that produces this result. This can only happen when changing lenses.
It is highly recommended that you only change lenses when necessary and that you point the camera body downwards when you are doing this. It is also better to change lenses in an environment which is not very dusty or sandy.
Also, make sure that your lenses are clean: whenever you change them, clean the back of the lenses using a microfibre cloth and always replace the lens cap when you are not using them. Similarly, do not remove the lens cap until you are ready to start taking pictures.
How to check the sensor
To check whether there is dust on your sensor, follow the steps below:
- Attach a lens to your camera.
- Select manual focus (M) via the adjustment dial and set the focus to infinity, the exposure compensation to +1 and choose the smallest aperture (the highest number), which will be f/22 or, on some lenses, f/32.
- Point your lens towards a source of uniform light that takes up the whole image (for example a window or the sky) and take a photo. Do not worry if the exposure takes a few seconds. You do not need a stand as the focus is set to infinity.
- Check the image. If dark spots appear, you need to clean your sensor.
Bear in mind that larger apertures mean that dust is less visible. From f/8 they become invisible. If spots appear in photos when using wide apertures, your sensor may be damaged and need repair.
How to clean the sensor
1. In-camera cleaning system
Your Sony digital SLR is fitted with an automatic sensor cleaning system which is activated every time the camera is turned off. In addition, the low-pass filter that covers the surface of the sensor is made of an antistatic material which prevents particles from sticking as much as possible. Unfortunately dust infiltration is not 100% preventable, especially if the environment is very dusty. If dark spots appear on your photos, you can activate a more thorough clean by selecting the cleaning function from the camera menu.
2. Manual cleaning
If the above method does not succeed in removing very sticky, oily particles (for example, pollen), you may need to resort to manual cleaning. Important notice: Sony cannot be held responsible for any damage that may result from mishandling while the sensor is being cleaned. Select the cleaning function from the camera menu. The camera turns off, and if you take off the lens you will see that the sensor is now visible. Point the camera body downwards and use a blowing ball to blow air onto the sensor.
Carry this out somewhere clean and non-dusty.
The blowing ball must never make contact with the sensor. Doing so may cause irrevocable damage to the sensor.
Do not blow with your mouth. Not only will this result in moisture entering the camera body, but particles of saliva may also damage the sensor.
It is also not recommended that you use air sprays that are designed for cleaning computer equipment (keyboard etc.). Their force could lead to the sensor being damaged and moisture and other residues entering the camera body.
It is strongly recommended that you do not use a brush or any of the cleaning solutions on the market. This increases the risk of damaging the sensor and the low-pass filter.
If in any doubt, please contact Sony for more information.
How to clean and maintain your camera body and lenses
Cleaning your camera body and lenses is essential to keep your equipment in good condition, but it is also a delicate procedure. That is why the best way to keep them in good condition is to look after them carefully:
- Always replace the lens caps.
- Keep your lenses in a protective case.
- Carry your camera equipment in an appropriate bag.
Some condensation may also appear if you are in a very humid location or if you move from a cold to a warm place. This condensation may lead to the oxidation of some of the metal parts inside the body, resulting in malfunctions. In addition, fungal and mould growth may develop and damage your equipment. To reduce this risk, it may be wise to keep sachets of silica gel in your carrying case. The silica gel will help absorb some of the moisture.
When handling your equipment, dust or other solid particles can lodge themselves in your camera body and on your lenses; fingerprints may also appear. Here is how to remove these without damaging your equipment.
1. Camera body
After a day at the beach, for example, grains of sand may lodge themselves in the crevices of the camera body. If they are not removed straight away, they may work their way into the adjustment dials, resulting in premature wear that will make your camera unusable. They can also harm the focus rings of your lens, seriously damaging it.
The simplest solution for removing the particles is to brush the outside of the body using a soft-haired brush. Do not press hard as this will scratch the body or the LCD screen.
A cotton swab may also be used if adhesive dust cannot be removed with a brush. A blowing ball is often effective for hard-to-reach places.
Finally, if the camera body is soiled with harder-to-remove substances (mud, etc.), a microfibre cloth (easily obtainable from an optician), slightly dampened with water, will be perfectly adequate. Microfibre is recommended as this will not scratch the LCD screen.
Do not use any chemical products such as thinners, benzine, alcohol, disposable cleaning wipes etc.
Lenses need to be treated with particular care. The glass that makes up the lenses is very fragile and can scratch very easily. A lens should only be cleaned as a last resort. The optical surface is affected each time it is cleaned. Marks are always left, even if they are not immediately obvious to the naked eye. It is better to have a lens that is slightly dusty than a lens that is scratched.
In our view, cleaning is essential if you notice fingerprints; by their nature these are oily and acidic, and can damage the anti-reflection coating of the lens. Dried water droplets and sea spray contain salt crystals that may also damage the glass and must be removed.
Removing dust and microparticles
First, use a blowing ball to remove most of the dust. Never blow with your mouth. Doing this results in particles of saliva on the lens which leave marks that are hard to remove.
Next, use a very soft-haired brush to remove the dust on the lens. Do not touch the hairs of the brush with your fingers as this will make the hairs oily and will result in smears. Do not press too hard. After a day at the beach, for example, microparticles of quartz or silica may be resting on the glass of your lens and improper cleaning may scratch the optical surface.
Removing oily smears and fingerprints
As a general rule, avoid touching the glass with your fingers. If fingerprints are present on the glass, never remove them using your clothes or tissue. Their fibres are too coarse and may scratch the glass.
- Use a microfibre cloth and keep it in a bag or your carrying case to prevent it from getting dusty.
- If you need to use a liquid to remove oily smears, do not use tap water as the salts in this may scratch the glass.
Instead, wet your microfibre cloth in deionised water and, without rubbing, dab the surface of the glass.