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TECHNICAL INFORMATION LEAFLET - (Printer friendly version)

CLEANING DIGITAL SLR SENSORS

There is a lot of information available on many websites and forums but for many people, the definitive method has yet to be clarified. It is also a question of mental attitude, as many methods shown are seemingly fraught with potential crisis risks, disasters ready to happen, conflicting statements and so forth - enough to put most people off the whole idea right from square one.

Provided a sensible approach is adopted, cleaning the sensor should be straightforward, simple and above all safe and effective. So, I present the following as a sensible and practical approach to this whole subject. The make of camera is totally irrelevant as the method is compatible with all digital SLR sensors.

First a brief description to put the whole thing into its proper perspective.

All sensors are covered with a protective glass cover, so you will not be touching the sensor itself, only its protective cover. Clearly one needs to be careful as marks on that cover, in effect, will show up as though on the pixels but with sensible procedures, you should be able to clean effectively and safely, if you follow the methods described in the TIL.

WHAT YOU NEED

Please note in the above illustration, the darker brush was included because the ordered same white nylon brush had not arrived by time article was posted. To differentiate, put a white tape around each and mark SENSOR and CHAMBER respectively.

If your digital SLR was supplied with a (1) mains adapter - then always have that plugged in, rather than rely on the batteries. Check the camera handbook to see the correct procedure to lift the mirror and open the shutter. Each camera will have a clearly described procedure in the handbook. If you do not have a handbook, go to the camera manufacturer's website and check for online manuals - usually in Adobe Acrobat (.pdf) format, which is in the form of a book. You should be able to download the file to your hard drive and access more easily once there. You can always print the whole book - or much more practical - pages as required.

A (2) vacuum cleaner with hose attachment, into the end of which you insert a bung with something like a metal or strong plastic tube. In effect, what you require is a piece of either rigid plastic tubing or some flexible plastic tubing; either will be fine for the job in hand. Check wine sections in chemists - or shops that sell accessories for wine making. You can usually get a cork with a metal tube through, to which you can attach a short length of plastic tubing - usually available same section. The purpose of this is to enable vacuuming of the inside of the camera as well as removing dust from the sensor. You need to be able to direct the end of the rigid plastic tubing or end of flexible plastic tubing to where you want without touching the focus screen, mirror or of course, the sensor cover glass.

I obtained a plumbing piece - fitted into end of hose pipe for vacuum cleaner, with help of some DUCK tape to make a good fit (so could be removed after use, of course!) that was an angled piece with about ½" outlet, that could go into the camera body yet was not doing enough to be able to touch the sensor. I found this fine at the start but soon adapted this and attached a cheap ballpoint pen casing, with ink tube removed, that I found easier to direct to where I required inside the camera body, without touching any part, as within ¼" works fine to collect dust as required. It is best to work all round the inside as small particles of dust are not easy to see, so just assume they are everywhere, which they probably are!

Either some (3) Methanol - as close to 100% pure as possible and not less than 97% pure - OR (3) pure alcohol - both should be obtainable from a chemist, although probably to order. You would only be using a few drops each time of either, so little volume required but you may have to get what's available. I had to purchase a litre of Methanol 99.9% here in Spain but I gather this will be the new "fuel" to operate a mobile 'phone charger, laptops and so forth, so someday I might even be able to see the level go down!

(4&5) Two stout pieces of card approx. 3" long x ¾" wide that you will use to act as support to a "wipe" for sensor glass cleaning. I made mine as shown below. PecPads have been recommended - but I have not found anywhere in Spain to purchase these. So, I just used (6) inexpensive paper hankies - the small pack ones costing pence. The cheaper ones do not have any Lanolin or suchlike extras added - they are just pure paper. I have found these OK - folded as later described and sellotaped on to the card support. The later illustrations should make clear what to do.

(7&8) Two nylon artists brushes - ideally same width as the sensor but I could not get one - just got a **12mm brush as shown. Details also given below, as you should be able to get these at a local art supply shop and a (9) wooden ruler. One brush is for the sensor ONLY and other for inside of camera so if the same - MARK THEM to suit. It is wise, even if you have managed to avoid touching the nylon bristles, to wash them right at the start. Put a couple of drops of washing up liquid on the bristles and work in with your fingers. Then put about an inch of warm water (to feel slightly hot to hand) into a clean cup. Donk the bristles gently on the bottom to ensure thorough washing to remove all traces of grease. This will also remove the concentrated washing-up liquid by it being dissolved out of the bristles. Shake brush (do not touch bristles!), rinse out the cup and repeat washing in clean water - changing about three or four times to ensure complete cleanliness. Finally, shake the brush well, dab it gently on clean paper to help remove moisture and stand in a clean place, bristles uppermost, to dry. If any potential dust, make a paper cover, loose, to cover the bristles. The brush could take a day to dry so be sure it is fully dried before using. You can obviously clean both brushes but it's the sensor one that really matters! My sensor brush is described as follows but note mine is actually a 12mm width (=No:12) because at time of purchasing, no No:15 (=15mm) ones were available in stock. The **15mm one would be a better choice, if available of course:

Ideally get No:15, Lotus, Deco, 8431, Pebeo, SRILANKA (or No:12 would be acceptable)

OR similar Nylon brush with soft, springy bristles

A (10) pencil with a rubber eraser affixed to its end. Cut a piece off a (11) micro-fibre lens cleaning cloth, fold and secure to end, with eraser underneath, fixing in place with some tape around the pencil body. Make at least two layers, with width approx. equal to sensor width (i.e. shortest dimension - but not essential as can be smaller). As previously, avoid touching this cloth where it is to eventually touch the sensor cover glass. This will give you a padded dry wipe device for later use.

A (12) small flexible lamp - there are some halogen flexible lamps available for around the £5 to £8 mark that are ideal. The one shown in my illustrations cost £5.99 from a DIY store, gives an excellent directable bright light, has a sturdy base, is flexible and only uses a 12V 20W lamp - but anything similar would be fine. I also use this when video messaging using "Messenger" on the Internet to illuminate my physog for the webcam, so everyone can see how handsome and youthful I iz. (Of course, I do tell some whoppers at times!)

Clean plastic bags - one to keep the brush in between uses, another for the card support device and another for storing the pack of paper hankies and finally, one for the wooden ruler.

NOTE: At no time touch the brush, hankies (the "working part") or anything else that will come into contact with the sensor as grease from fingers is easily deposited on the surfaces and thus transferred to the sensor cover glass; this also applies to the mirror, of course!

That's the list of requirements, being 12 in total plus the bags. You will see from the illustrations what I use but you can adapt as suits your own preferences.

A Word of Caution before you begin. Ensure you are wearing dust-free linen clothing and not woolly materials. Preferably also wear some sort of dust-free cap or hat - like a peaked cap - to prevent hairs falling or of course sawdust from the termites and woodpeckers! Make sure the working surface is clean - ideally put a piece (or pieces) of clean paper down to work on. It's really just commonsense to work in as clean an environment as possible.

FIRST STEPS

Remove lens and store safely - being careful to not place rear-of-lens down if the rear element could thus be damaged. Ideally, ensure the lens has both front and back covers attached - or put a piece of clean card or paper over the uppermost end to keep clean. Use piece of clean linen (old hanky?) to wipe round camera's lens mount surfaces to remove any grease.

If you have a Sigma SD9 or SD10 DSLR, you will need to carefully remove the "behind the lens" protective cover glass, fitted just inside the camera body lens-mount area, as described in the handbook. You need a small cross-head screwdriver (only one screw to remove) and a pair of tweezers - or you can use a small piece of BluTack on the screwdriver (I use this on end of screwdriver so the loosened screw will also be captured, so can thus be removed and placed somewhere safe whilst undertaking cleaning to ensure a) it's not lost and b) it's not accidentally sucked into the vacuum cleaner! This cover glass also will need cleaning via breathing and use of a lens cleaning cloth in due course, immediately before replacement. I also vacuum mine before replacing.

Remove memory card and store safely - note that some cameras will not function if this is removed, so check handbook. It is preferable to remove card if possible - or at least ensure it contains no valuable images not yet copied to hard drive, etc.

Fix folded strips (cut lengthways as required) to cover both ends of the two card supports and tape in the middle. One will be used - both ends in turn - with a couple of drops of chosen liquid to act as wet wipes for the sensor cover glass BUT only add the drops just before required. The other will be a dry wipe, used after both ends of the other have been used for wet wiping actions.

Flick the nylon brush for inside of camera (for the focusing screen and the mirror only) across the ruler about 10 times up&down to charge with static electricity to be able to attract dust - and gently brush those to remove dust - flicking each time to recharge with static electricity.

Vacuum the inside of the body with the mirror still down, lifting the mirror gently at edges to thus be able to vacuum the rest of the chamber. Be careful not to actually touch either the focusing screen, the mirror and especially, the shutter blades as all those could be damaged. Just ensure the end of your rigid or flexible tubing cannot touch them - put some white or distinctive coloured tape on the tubing to mark the safest working position inside the camera body - when the vacuum is turned off, of course! You do not want the end to get closer than about ¼" or any surface.

Once this has been done, lift the mirror and open the shutter to expose the sensor as per your instruction book.

Hoover inside - around sensor, walls and suchlike - ensure that sensor cover glass is not actually touched - ¼ above is fine for sucking loose particles.

Have a folded wipe-pad already attached to each of the stout card supports. Put a couple of drops of your chosen liquid on the end and gently wipe to and fro a couple of times. Change end and repeat. The bright light helps see what you are doing at this stage - just angle to shine down into the camera chamber.

Then use the other dry pad to wipe the sensor cover glass dry - again use both ends.

Now, gently (yes, really!) breath on the cover glass and wipe/polish using the micro-fibre cloth on end of the pencil. Repeat a couple of times.

Now, vacuum again as per above.

Charge the brush for the sensor using the ruler as before and pass the brush across the sensor left to right with bristles gently in contact once, then back again a sort-of gentle painting action, to and fro once each way. Recharge the brush (which also removes any collected dust particles) and repeat as before. Give a final vacuum again and place camera face down on a piece of clean paper. Per instruction book, close shutter - which will also drop the mirror - and turn camera off/disconnect the power supply as required.

Clean rear of lens - use clean linen (old hanky?) for the lens mount - to remove grease from fittings. Then breathe on lens surface and gently clean/polish with the remaining part of the micro-fibre lens cloth - or use your normal lens cloth as preferred.

Replace lens. Set lens to infinity, aperture to f22. Take shot of plain~ish area (sky - even with/without clouds is OK) after getting exposure from a suitable midtone area (like ground or grey card) as exposure read from sky would give an underexposed image.

Import image(s) to computer and magnify and check your cleaning. f22 aperture and infinity focus will show up any dust or other marks. If unacceptable, repeat cleaning procedure and check again. The first time, you may need to repeat a couple of times to get rid of stubborn spots but do remember that actual pictures may well disguise marks, unless in sky or other plain areas and in any event, a wider aperture, like even say f11, would probably not show the marks that were visible when f22 was used.

After such a thorough clean, you should find that occasional use of the nylon brush on the sensor cover glass is all that is required to keep images free of spots. Changing lenses can introduce dust, so keep camera open side down when changing lenses and try to also keep away from breezy and dusty areas during such actions.

You will never totally eliminate all dust spots. Some will be generated by tiny pieces from the shutter or mirror mechanisms but most can be tolerated as so easy to cleanup using the Clone (Rubber Stamp) tool in image manipulation programmes. Rule of thumb is to not undertake cleans until you have enough dust spots to start taking time to repair/retouch.

There are several websites and articles on cleaning sensors, which are useful in that they are illustrated. However, I recommend using the above procedure rather than anything you may see recommended. Just use the link pages information as extra useful data. The vacuum cleaner routines are, in my opinion, essential. Here are some links you may like to use for further information before commencing sensor cleaning. You can always print out anything that might be helpful.

http://www.pbase.com/sigmasd9/sensor_cleaning A detailed illustrated article by Günter Hördt and Laurence Matson for Sigma cameras

http://www.pbase.com/copperhill/ccd_cleaning Useful in general terms

http://www.bythom.com/cleaning.htm Another useful link especially for Nikon cameras

http://www.cleaningdigitalcameras.com/ Yet another - by professional camera repairers

© - BRIAN SL ALLEN - 2006- ©

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