This page is designed to help the
countless new DSLR owners who discover that their new camera is
afflicted with that dreaded scourge of the DSLR shooter:
Below we see a typical example of a
DSLR image with dust spots.
The arrows point to the most blatant
spots in the image. There are many smaller ones as well.
This photo was taken with my Canon
20D within a month of receiving the camera. I had only one lens
had not removed it from the body the whole time. So I was
dismayed to see these spots appear in my images. I wondered if
the camera was defective because I had not heard of "sensor dust".
By doing a bit of Internet research I found that these spots are quite
common and are the result of tiny pieces of dust which have settled
onto the camera sensor's filter.
Such dust casts shadows onto the sensor as you take your photos and
thus shows up as darker spots, smudges, or squiggles depending on the
size and shape of the dust particle.
Smaller lens aperture settings (higher f/numbers) exacerbate the
problem because the smaller
aperture appears as more of a point-source for the light entering the
camera and thus causes the dust particles to cast more distinct
shadows. Think of the way you cast a distinct shadow on a clear
day versus the way you may cast no visible shadow at all on a cloudy
day when the light comes from the entire sky instead of the "point
source" of the sun.
Some people never notice that they have dust on their sensor filter
because they shoot using large lens openings (small f/numbers).
Some people go so far as to recommend that you avoid using small
apertures in order to keep dust from being visible in your shots!
Personally, I feel that you should be able to use any setting your
camera has and the choice of f/stop setting should be based on other
Where is this darn dust, how do I get rid of it, and how do I
prevent it from happening in the first place?
DSLR Dust Rules:
Dust that shows up in your photographs pretty much has to be on
your sensor filter.
Dust that shows up in your viewfinder pretty much has to be on your
Focusing screen dust cannot show up on your photos.
Sensor filter dust cannot show up in the viewfinder.
What about dust on the mirror?
Dust on the mirror cannot show up in your photographs because the
mirror flips up out of the way when you take a picture. And dust
on the mirror will not be clearly visible even in the viewfinder
because it will not be in focus. If you've got a major-league
dust bunny or hairball on the mirror, you might notice an indistinct
shadow through the viewfinder, but it would have to be a large piece
for that to happen.
In general, dust on the mirror won't cause any problems at all.
The mirror has a delicate surface that is easily damaged, and since the
mirror is mounted in a delicate manner and its position is very
critical to both autofocus (due to the relay mirror mounted to it) and
manual focus (because its position affects the light path length to the
focusing screen), I highly recommend that you treat the mirror with
How about dust on the front or back of the lens?
As with dust on the mirror, dust on the lens will generally not be
"in focus" at the sensor or the focusing screen. Dust on the lens
surfaces will lower contrast by scattering light and can cause extra
flare or a general lack of sharpness in an image. But again, it
normally won't cast any distinct shadows and so can't show up in your
Huge chunks of dirt or raindrops on the front element (or the front
surface of a filter used on) a wide angle lens may show up in photos
taken at small apertures. The depth of field for such an
arrangement can be so great that large things on the lens can be
But tiny pieces of dust won't show up as spots even with a wide angle
is a shot where you can see raindrops on the front filter of a Canon
10-22mm lens used on a 20D. It's time to take the camera back
inside, I guess.
Of course, raindrops are large
and easy to see so you'd know you needed to clean the front of the lens
in this situation.
It pays to keep your lenses clean, but generally, when you see spots in
the viewfinder or on your photos, the problem will NOT be dust on your
DSLR camera design:
A DSLR's construction is just like a "normal" film SLR in many ways.
Studying this drawing, you can see
that when viewing through the DSLR, the light enters through the lens
and strikes the primary mirror. This mirror is semi-silvered and
reflects much of the light upward. That light then focuses and
forms a visible image on the matte surface of the focusing screen.
The focusing screen behaves as a rear projection screen. This is
similar to the screens used in LCD or DLP Projection type television
sets. The image is projected onto the back side and we view
through the clear plastic to see this image from the other side.
In the case of the SLR camera, a pentaprism or pentamirror arrangement
allows us to see the image from the convenient eyepiece on the back of
the camera. This allows for the familiar and comfortable "eye
level" camera SLR position when
composing and shooting.
The eyepiece lens serves to make the projected image appear to be
approximately 1 meter from the photographer's eye. That "apparent
viewing distance" is chosen to make it easy for most people to see the
focusing screen clearly with their normal eye correction (glasses,
contacts, or unaided eye). Basically, this is a comfortable
viewing distance for most people.
Troubleshooting Camera Dust:
From this drawing, you can see why dust on the mirror would not
form a focused and distinct image on the focusing screen. So
dust on the mirror is not likely to be visible through the
viewfinder. Thus the rule that
dust on the mirror isn't likely to be visible in the viewfinder unless
You can also see how dust on either the mirror or the focusing screen
cannot affect the photos taken because the mirror flips up to the
position shown at number 3 during the exposure. This
configuration allows the light from the lens to pass through the
"mirror box" unimpeded and focus directly onto the sensor. Thus the rule that dust visible in your
photos cannot be on the mirror or the focusing screen.
It should also be clear from this drawing that dust on the lens
surfaces would not form clearly defined shadows either onto the
focusing screen when viewing through the eyepiece or on the sensor when
the exposure is actually being made. Dust on lens surfaces will
generally not be in good focus at the focusing screen or sensor. Thus the general guideline that if you see
dust through the viewfinder or see dust shadows on your pictures, the
lens is unlikely to be the cause.
But, we can also see from this drawing that dust on the focusing screen
will show up very clearly when viewing through the camera's
viewfinder. It can't affect our photos, of course, but it may be
annoying. Thus the rule
that if you see dust through the viewfinder, the first thing to suspect
is the focusing screen.
And we can also see that dust on the filter in front of the sensor can
cast shadows onto the sensor during the exposure of an image, and thus
show up in our photographs. Once again, dust on the sensor filter
cannot show up in the viewfinder. Thus the rule that if you see dust spots on
your photographs, there must be dust on the sensor's filter.
So now we've established where the dust is. What now?
Dust on the primary mirror will not be distinctly visible through
the viewfinder and will also not show up in your photos.
The primary mirror is semi-silvered to allow some light to pass through
it so that the autofocus system can get its "view" through the lens via
the relay mirror. The position at which the primary mirror rests
is critical to the functioning of the autofous system. Likewise,
the position at which the attached relay mirror rests is also critical
to the correct operation of the autofocus system. If you knock
either mirror out of alignment somehow, your AF will be out of
The semi-silvered surface of the primary mirror is also delicate and
could be scratched quite easily.
Since dust on the mirror won't be visible on your photos, and since
only huge chunks of dust or lint would even be detectable when viewing
through the eyepiece, there is little to gain and much to lose by
attempting to clean the mirror.
Still, there could be times when you find it necessary. In that
case, be very gentle so as not to disturb the mechanical alignment of
the mirror(s). And be careful of the surface so as not to scratch
it. I recommend that you simply use a bulb blower for this
too. If it works, then you have not touched anything at
all. You gain access to the mirror simply by removing the
lens. DO NOT use the sensor clean mode! The sensor clean
mode flips the mirror up so you would not be able to get to it's front!
The red arrow indicates the primary
mirror. Simply removing the lens reveals the mirror.
A bit of exhaled breath into the mirror box can provide
moisture to dissipate static that might be holding stubborn dust to the
mirror. So you could give it a nice, easy breath and then blow it
off with your bulb blower.
Now please understand this:
When I say to breathe into the camera's mirror box, I'm not asking you
to blow into it! Blowing with your lungs and mouth is often
something that comes to mind when we want to blow dust or lint off of
something. But the problem is that if you blow hard enough to do
any good, the velocity of the air coming out of your lungs and through
your mouth will be high enough to pick up droplets of spittle.
want to blow droplets of spittle into your camera or onto a lens,
etc., so don't blow! Yeah, you can clean it off later, but it's
much better to
just not have it happen to begin with.
So when I suggest breathing into the camera to deposit some moisture or
humidity, I'm asking you to breathe out very slowly with your mouth
wide open so that you do not generate any high-velocity air but instead
just get a nice, slow, gentle flow of moist air from your lungs to go
into the camera. In fact, by exhaling very slowly, you may
actually increase the humidity of the air. We're just trying to
get some moisture into the area in question.
Anyhow, the combination of high moisture followed by a good blast or
two from the bulb blower will normally get anything that
would be any problem. It's fortunate that only huge dust or lint
on the mirror will be visible, and such large pieces are the easiest to
Again, if all else fails you may feel that using a brush or other
implement touching the mirror is necessary. You do this at your
own risk, of course. I'm not saying it can't be done. I've
"haze" of gunk (long story) off of mine with a cotton swab and
solvent. But I am saying that it's potentially risky, and you
know what the
consequences might be when you undertake such a procedure. It is
almost never necessary and must be done with extreme caution.
This is something you might be better off having done by an authorized
Using a bulb blower to blow out
Focusing screen dust:
If the dust is visible through the viewfinder and is sharp and
distinct, it is almost certain to be on the focusing screen.
Thus, you may not care to do anything about it. After all, it
won't affect your photos.
On the other hand, it might be irritating to look at and could possibly
(not likely) cause metering errors since the Canon DSLRs meter by
looking at the top of the focusing screen just the way we look at it
through the viewfinder. You would need to have an awful lot of
huge chunks for this to be any concern.
But let's say that this visible dust bothers you enough to want to get
rid of it. How do we proceed?
The dust is most likely to be on the underside of the focusing screen
because that side is exposed to the interior of the mirror box.
You could have dust on the
top of the focusing screen, but it's far less likely.
The focusing screen is shown in this
view through the lens opening looking upward. The screen forms
the "ceiling" of the mirror box.
The focusing screen is made of plastic in most of these cameras and it
is quite easy to scratch or mar. So touching it
with anything is very risky. The good thing is that if you do
it, it's just the focusing screen and it won't directly affect your
just like the dust on it doesn't!
Still, I advise that you don't touch the screen with anything and
instead use a bulb blower to blast the underside of it to try to
dislodge any dust. The bottom of the focusing screen is visible
accessible by simply removing the camera's lens. You DO NOT want
use the camera's sensor clean mode for this because the mirror will
up and cover the screen!
So just take off the lens and then blow the underside of the screen
with your bulb blower and
see if that doesn't get the dust off. Sometimes static
will hold the dust to the plastic screen and in those cases, simply
breathing (again, gently as described above) into the open camera may
provide enough humidity to dissipate the static charge
and allow the next blast from your bulb blower to get the job done.
You could use a soft brush to try to knock stubborn dust off of the
focusing screen, but I've never found that necessary and you risk
damaging things this way. And rubbing most brush bristles across
the plastic can impart an even greater static charge to the screen
then attracts and holds dust even better!
Remember that dust on the focusing screen won't show in your shots
anyhow. Why get too worried about it? It's purely cosmetic.
Finally, we get to the main point of this all! Dust on the
filter (number 8 in our drawing) ahead of the
sensor can cast shadows
onto the sensor when we take a picture. This is really the only
place that dust can normally be to cause visible dust marks on our
The dust is held slightly away from the actual sensor by this filter so
if we use a larger lens opening (small f/number), the dust may not be
visible in the photos at all. You can see how light from a larger
area can find many paths to reach any given location on the
sensor. Many of these paths can "get around" the dust
speck. But when we stop the lens down to a small aperture (high
f/number), the light must pass through that small aperture. And
as this aperture becomes smaller, it reduces the size of the "light
source" and thus the shadows become ever more distinct.
To test for dust on the sensor filter, take a photograph of a
bland background (I like a white wall or piece of paper, but you can
also use a clear-blue sky). Take the photo with the lens adjusted
so that the wall, paper, or sky is out of focus (we don't want to see
dirt on the wall, marks on the paper, or birds in the sky). And
use the smallest aperture (highest f/number) for the lens. This
will make sensor dust show up easily.
Many people process their test shots in a photo editing program and
turn up the contrast or do an "auto levels" adjustment to make the dust
more distinct. You can do that if you want to, but you may not
like what you see :)
For me, I'm just interested in detecting dust that will be likely to
affect "real" photos that I'll be taking. So I just take the test
shot and then view it on the rear LCD of the camera while zoomed in and
"panning around" to cover the whole frame. Anything that shows up
when doing this is something that I want to get rid of because it is
likely to show up in real photos.
Here's what some typical sensor dust of
mine looks like zoomed in while reviewing one of my dust test shots:
My camera's "Multi Controller" gets a workout as I scan the zoomed area
around to inspect the entire frame at high magnification. The
alternative is to unload the photo to your computer and view it on
screen. I find this method to be faster because you can switch
between cleaning and testing in seconds.
Oh, Darn! I've got
dust! What shall I do?
Once you've established that you have dust on your sensor filter
that will affect your photos, you're faced with the question of what to
do about it.
First, read the manual that came with your camera. The
manufacturer will detail their approved method for cleaning dust from
the sensor filter. Read these directions carefully and do what
For the Canon 20D, the first recommendation is to install a freshly
charged battery or use the AC power adapter. I recommend using
the battery because I don't like the idea of what would happen if I had
a sudden power failure (mains failure) while cleaning my sensor
filter. I also don't like the idea of using the battery grip
since there have been reports of intermittent power contact when using
the grip. So for me, I put a "known good" and freshly charged
battery directly into the camera and then proceed.
Next, the 20D manual says to remove the lens from the body. That
makes sense. I don't know how you'd do any cleaning with it in
Then you are to put the camera into the sensor clean mode. When
you do that, the mirror pops up and the shutter flies open and they
both stay that way.
You can now look into the body and see the sensor through the stack of
filters. It's an amazing sight. That's a huge integrated
circuit. No wonder the darn things are so expensive! Check
it out. It's worth a look even if you don't need to clean it.
On the 20D, if the battery is too discharged for safe sensor
cleaning, the camera will not go into the clean mode. If the
battery gets low while the camera is in the cleaning mode, the camera
will beep to warn you that the power may fail.
With the camera in the Sensor Clean
mode, the mirror flips up and the shutter opens. Thus, the sensor
is visible through it's stack of filters.
What's the big deal with running out of power while in the
sensor clean mode?
The camera requires power to hold the shutter open and to hold the
mirror up. If you were to lose power while cleaning the camera,
and if you had something inserted into the body of the camera, the
shutter might try to slam closed on that tool and the mirror might also
flop down onto it. Thus, the shutter and/or the mirror could be
The manual for the 20D tells you NOT to insert the nose of your blower
beyond the lens mount, so you'd be safe even if you did lose
power. But the fact is that some cleaning methods require you to
insert a tool into the body so that you can wipe the sensor
directly. In that case, a power loss could be very dangerous.
With the camera in
the sensor clean mode, hold the body so that
the lens mount is aimed down and blow upwards into the camera to
dislodge as much dust as possible. This is the Canon recommended
This is the exact same method used to clean the mirror and focusing
screen. That's why this photo looks so familiar. Blow the
sensor vigorously and repeatedly with the blower. You want to
blow the dust off of the sensor and completely out of the camera.
Give it a bunch of fast, hard pumps and then switch the camera
off. That will take it out of the sensor clean mode and you can
then install the lens again. I often blow off the back of the
lens right about now and then put it onto the camera quickly to prevent
more dust from getting into the body.
A bulb type blower aimed upwards
into the camera.
Now, you should perform another dust test shot. Check that shot
and if all is well, then you're done! According to Canon, this is
all that you will ever need to do to get your sensor clean. Often
this is true.
Oh oh. There's still dust on my sensor filter!
OK, don't panic. A lot of times, just blowing the camera
does not get all of the dust off of the sensor filter. This is
because the dust is stuck there. Why is it stuck there?
If you exposed the camera to something wet, like changing lenses while
at the beach with some nice salt spray on the breeze, then there may be
residue from that on the sensor filter. This isn't very likely,
though, because even when you're changing lenses, the shutter is closed
so anything that gets into the body won't get directly onto the sensor
filter. Instead, that salt spray should just get on other things
in the camera and dry there. So at the worst, you've contaminated
the body with salt residue which can break free later and act as any
other dust. Not too bad.
But there do seem to be things that will stick to the sensor filter and
for whatever reason, they need to be washed off.
But we'll start with the most likely reason that your dust didn't just
blow off of the filter. Think about what this filter is made
of. It's glass of some sort. And it most likely has some
anti reflective coatings applied to it. Since Canon and the other
manufacturers don't tell us what these coatings are, we are left to
speculate. But it's possible that they are materials that tend to
be prone to holding a static electric charge. Bare glass is
pretty good at that all by itself and the coatings may be worse.
So it's reasonable to think that the sensor filter may have a static
charge on it. And if you combine that with dust made of materials
that also tend to accumulate a surface charge, you've got a recipe for
"stuck dust". Pollen is often regarded as being a problem because
it's tiny and very static-prone. All the blowing in the world may
not knock things like that free from a highly charged filter.
So one thing you can try that is very safe and easy is to simply
breathe into the camera while it's in the sensor clean mode to raise
the humidity in there. Once again, let me repeat that I don't
suggest "blowing" into the camera. Blowing implies making the air
come out of your lips at a high velocity. High velocity air can
easily pick up droplets of spittle and then they'll fly in and land on
your sensor filter. That's not what we want.
Instead, breathe out gently and slowly with your mouth open fairly wide
so that your warm, high-humidity breath just slowly enters the
camera. The moisture from your breath is what we want. Not
any kind of blowing action.
The humidity from your breath will often allow the static charges
on the dust and the sensor filter to equalize and dissipate.
Then, a good standard blowing with the hand blower may well get the job
done. Give this a try.
Again, don't spit, wheeze, cough, or blow into the camera and onto the
sensor. Just breathe slowly into the camera to get some moist air
Now you need to test again for dust. You might have
success and it's pretty easy to try it. If that got things
cleaned out to your satisfaction, you're done!
NEW: The Canon
1DMkIII, 40D, and 400D are reputed to now have a Tin Oxide coating
(actually, I suspect that it's more likely to be a tin-doped indium
oxide coating) on their sensor filters to eliminate static. This
sounds like a good idea to me and should help with dust. Thus, it
may not do any good to breathe into these bodies to try to dissipate
the static charge on the filter. But it might still help to
discharge the dust itself. It's hard to know. I don't think
breathing into those cameras will do any harm, however, so it's
probably still worth a try. The 5D also has a different front
surface on its sensor filter. But it's not the same as that on
these newer cameras. We don't know much about that one.
Oh darn! There's STILL
dust on my sensor filter!
Alright. It's OK. You're now where most of us have
been at times. You've done what the manual recommends and it
didn't get it all. Next, you've tried a bit of humidity to help
out, and maybe that didn't get the job done either.
Now you've got to ask yourself a question or two:
Do I dare do something that could damage my camera's sensor filter in
order to get the dust off? Or do I need to send/take the camera
to Canon to have it done?
That is a tough question because you are only authorized by Canon do
use the blower. If that didn't get the job done, and you don't
want to potentially affect your warranty coverage, you are done.
You'll just have to live with the dust you have or send/take the camera
to Canon to have them clean it.
I can't tell you what decision to make at this point. I know what
I do and I also know that if I wasn't willing to go further on my own,
the camera would be nearly useless to me. I get dust on my sensor
filter frequently. Where I live it's dry and dusty. I have
six cats and I clean the box. That stuff is dusty! And to
top it all off, I shoot a lot of macro photos and that requires the use
of very small apertures at times. So I see any little bit of dust
in many of my photos.
As a result of all of those factors, I have arrived at a fairly fast,
easy, and cheap way to get my sensor filter clean. I do it
frequently. Probably an average of once or twice a week, but
timing means nothing. It all depends on what I've exposed the
camera to and what I'll be shooting. If I'm about to shoot macro,
I test and clean as necessary because I'd rather spend five minutes
cleaning my camera now than spend five minutes per photo "cloning out"
the dust spots later. It's just simple time management.
And I live in the middle of Wyoming. We don't have an authorized
Canon repair station nearby. The nearest one is in California, I
believe. Imagine me sending my camera in for cleaning twice a
week. Does that sound practical? How many bodies would I
need to own in order to keep a constant flow of bodies in transit
between me and Canon?
So I clean it myself. I take full responsibility for damaging my
sensor filter. I know it'll cost a bunch to have it replaced if
it is damaged. I accept that and proceed with care and attention
to detail, but in a fast, cheap, expedient way.
The rest of this article describes what I do. I can't
authorize you to do it this way. In fact, I'll tell you again
right now that this is not
authorized by Canon and any damage you do to your camera is your
You've been warned!
Read the additional warnings
at the end of this page too!
you have one of the newer cameras with anti-dust features or if you
have a 5D, REALLY read those warnings carefully!
Many fine tools are available to clean your DSLR's sensor filter.
Most of these involve the use of a swab of some sort which has a flat
profile. The swab is moistened with a small amount of Methanol
and is then drawn across the sensor carefully in one pass to wipe the
dust off and collect it. These systems work very well from all of
the reports I've read.
Another common method is to use a brush of some sort to brush the dust
away. The brushes are often pre-charged with static electricity
to make them more attractive to the dust than the sensor filter so that
the brush will collect the dust rather than simply push it
around. Again, from reports I've read, these brush methods work
But I wanted something easier to use and less expensive so I did the
unthinkable and tried plain old generic cotton swabs. How
Those can't work. They aren't high tech. They don't cost
enough. It's just too darn easy!
Well, I'm sure these other methods have advantages. And they're
well tested and loved by many. So I'm sure they're just great.
But the actual thing touching the sensor filter with any of these other
methods is, in every case, something at least as "hard" as cotton.
In the case of the various swabs, the material is usually
cellulose. They are a highly refined paper. Cotton is
another form of cellulose, and is often regarded as being softer than
paper products. Hmmm, that seems OK.
So where is the danger with any of these methods?
That's what you need to beware of. If you use any of these
"touching the sensor" methods, and you happen to have a particle of
hard grit (sand or dirt) on the sensor, you run the risk of forcing
that grit against the filter and dragging it across it. That
would surely scratch the filter. It wouldn't matter what your
swab was made of, or even if you were using a brush. If you drag
a particle of hard, sharp grit across the sensor filter, you may
So regardless of what you use as a swab, your enemy is grit. This
is why it's very good practice to pre-clean your sensor carefully with
the blower before using any "touching the sensor" method. Always
try the blower first. Only move on to any of these swabbing or
brushing methods if you've already blown the sensor filter off well
and tested to be sure the swabbing/brushing is required.
I buy generic cotton swabs at the local drug store and I keep them in
sealed zip-top plastic bags containing about 20 swabs each. That
way, I can keep them clean and if I think a bag of them may have gotten
contaminated, I just throw the whole bag away. These things are
cheap. There is no sense risking the use of a contaminated swab
when they cost a half a cent apiece!
And on the subject of contamination of the swabs: When you grab a
swab out of the bag, decide which end you'll be using to do the
swabbing, and which end will be in your hand. You don't want to
touch the end that you'll be using for the swabbing because your skin's
oils and dead cells, etc., will contaminate the swab and end up
smearing your sensor filter.
Keep it clean.
One more thing about the swabs:
I have found that these generic swabs from the local drug store work
better than the "brand name" swabs or the special "high-quality" swabs
often sold for delicate cleaning operations. The reason is that
the generic swabs' heads are wound looser. The fancy swabs often
have their heads wound very tight. This may reduce fiber
shedding, but it also means that the tip of the swab is small and
tight. The looser-wound generic swabs cover more area in a pass
than the tight, hard ones do. This makes it easier to cover the
area quickly in less passes and it allows the end of the swab to mash
down with very little force applied. The loose swabs get into
corners better too.
So while it might be tempting to use the very high quality individually
packaged swabs because they should be cleaner, etc., it has been my
experience that they don't work as well because they are not as
compliant. So the best swabs I've found are the generic ones from
the drug store. I suspect that there can be a lot of variation
from brand to brand. Try a few different brands and find one that
works for you. You want a swab tip that is soft and fluffy not
hard and tight. You'll be mopping the sensor filter.
Imagine mopping a floor with the end of a stick - wouldn't work very
well, would it? You want the mop head to cover some surface area
without needing to apply a lot of force :)
It is possible to wrap a Pec Pad around a cotton swab to make a handy
swabbing tool too. So if you'd rather have a Pec Pad in contact
with your sensor filter, that's an option. But I've had good luck
with the raw swabs so take that all for what it's worth.
OK, OK. We're ready to swab, already.
First, I assume that your camera is at normal room temperature of
around 20 degrees C (68 degrees F).
It's nice to have a good, bright lamp to work under. I like
those swing-arm lamps because you can position them for good
viewing. But this isn't completely necessary.
Take the lens off of your camera. Set it aside.
Take out a swab or two and set them down on a clean surface remembering
which ends are the "clean" ends.
Now, I'm right-handed so I'll describe this as if you were too.
If you're a leftie, just use the other hands. No problem.
Put the camera into the sensor clean mode and turn it up so that you
can see the sensor. Of course, you're actually looking through
the clear filter, and that filter is what you'll be cleaning, but you
get the idea.
Hold the camera in your left hand so that the opening is facing up and
you can see into it nice and easy.
If you get the camera and the light just right, you can see the whole
surface of the filter, and you can rock the camera around to get the
glare from the light to reflect off of that surface. That makes
it easy to look for dust, smudges, and other stuff.
You won't be able to see the dust, usually. If it's a whopper, or
a piece of lint, you might, but generally, by the time you've blown the
camera out a few times, you've gotten rid of anything large enough for
you to see. But check it out anyhow! If you see anything
that looks like it could be a piece of hard grit on there, you need to
think about how to get it knocked and blown off of there before you do
You can poke at it gently with a clean swab and see if it'll move and
then blow it off. (Pitch the swab and get a clean one now).
OK, everything looks good? You're ready to swab.
Pick up one of the swabs in your right hand being careful not to touch
the "business end" of it.
Hold the camera up and gently breathe (once again, do not blow, sneeze,
cough, or wheeze - just breathe out slowly with your mouth fairly wide
open) into the body. You will see
a fog of condensed moisture form on the sensor filter.
That fog is actually condensed water. By definition, it is
distilled water. And further, it's been fractionally distilled
because the temperature of the inside of your lungs is only a few tens
of degrees warmer than the surface onto which the water condensed.
Thus, this is extremely pure water. A friend of mine who is a
chemist pointed out to me that there will also be other gas components
of your breath which will end up dissolved into that water too.
One main component of note is carbon dioxide. That CO2 will form
carbonic acid in this water.
Those acid ions will make the distilled water (a good
insulator) into a reasonable conductor. Thus, this slightly
acidified water will work well to equalize and dissipate the surface
charge of the filter with respect to any dust that is on it. This
will make it easier for the swab to remove the dust from the filter.
Canon 20D camera sensor with its filter
"fogged" over with condensed breath.
With the filter fogged as shown, you're ready to swab. You've got
just the right amount of water to do the job. It won't be so much
that you are in any danger of having it run in anywhere yet there is
enough there to let you "mop up" the dust.
This photo doesn't show the ideal pattern for swabbing the sensor
because I had to take these shots with an uncooperative P&S camera
in one hand and the swab in the other while holding the shutter button
at half-press after trying to lock the focus..... Well, you get
So this photo just shows how the condensation is picked up by the swab
as you rub it gently over the surface of the filter.
In actual practice, I use a "raster" pattern to scan over the whole
surface and then I run the swab around the edges a few "laps" to get
the dust that likes to hide in the corners and along the edges.
I don't use much pressure, and I don't need to because unlike with the
paper covered spatula technique, I can get the whole surface in due
time and I can see where I've been because of the moisture that is
being smeared around as I do this.
By looking at the filter as you swab it, you can see where you've been
and you can see when the water has been polished off of the
surface. When the water is gone, you're done.
Swab removing the water as it cleans
This shot shows the swab against a dry filter. When
it's this dry, you don't need or want to continue with the swabbing.
Yeah, the swab has mysteriously moved to my left hand. I'm sorry,
just a continuity error there. Again, I'm shooting the other
camera one-handed so that's the way it goes. Let's say this one
is for the left-handed folks out there.
The filter is dry, so you're done
I run the swab back and forth over the sensor in a pattern
like this to get the whole surface clean.
I can see where I've been by the patterns left in the water on the
The final step for me is to run the swab around the outside perimeter
of the sensor, up against the edges of the "well" that it sits
in. I often make a few laps around the perimeter like this since
that's where a lot of the dust seems to end up.
One possible swab wiping pattern.
The main thing is to get the whole surface wiped while there is some
moisture there to help out. As the moisture is spread around and
evaporates, you can see where you've been and see if the surface looks
clean. Once the water is gone, and the surface is shiny and free
of streaks, you're done.
The whole process takes about ten seconds.
Throw the swab away. If you decide to swab again, you should use
a clean swab. Hey, they're ridiculously inexpensive!
The final blow:
Now that you've swabbed the whole sensor, you have one final thing
to do. Get the bulb blower and again hold the camera so that the
lens mount is aimed down. Do another good, vigorous blowing to
get any loose fibers that may have shed from the swab and also any crud
that may have fallen into the camera while it was aimed upwards.
Blast it good!
Now, turn the camera off to take it out of sensor clean mode, and put
your lens back on.
You may now test for dust once again.
It may not be perfect at this point, but I'll bet it's pretty darn
close. And if it's not, you know just how easy it is to simply do
the same thing again. Sometimes it takes a couple of
swabbings. That's fine. It's cheap and fast.
As you do this a few times, you'll get very good at it and become more
comfortable with the whole process. You don't need to press hard
at all because the swab conforms to the corners and the surface.
And you can get into all of the edges and corners with ease.
There is one protrusion on the left side of the "sensor well" that is
kind of in the way as you swab (on a 20D), but you soon get a feel for
where it is and it's no trouble to angle the swab to avoid it so that
it doesn't interrupt the smooth motion of the swab.
A nice, gentle, smooth wipe seems to work the best. Bring the
swab into contact with the filter just once and keep it in contact for
the whole wipe if possible. That seems to get the dust the best.
You'll get a feel for it after a few tries. Don't expect
perfection the very first time. But also don't expect this to be
difficult or hard to learn.
warning below concerning new cameras with special anti-dust coatings).
I have gotten oil on my 20D sensor filter before when using a
clean it. I must have touched something in the camera that had
some lubricant on it and then transferred that lube to the
sensor. That sounds nasty, but really it wasn't much of a problem
at all. I simply used some alcohol and a swab to remove the
oil. Various alcohols are available for this use. The most
common one used in the commercial sensor cleaning preparations is
methanol. That works fine on the 20D. See below for other
However, another good, clean source for a cleaning alcohol is to
new bottle of "Everclear" at the liquor store. Everclear is 95%
pure grain alcohol (ethanol). It seems to be very pure and free
of impurities that would leave a reside. I've used it a number of
times when I wanted a less polar solvent than water. For greases
and oils, it is reasonably effective.
Again, use it at your risk, and only use clean Everclear from a fresh
bottle. You may wish to keep a bottle just for that purpose so
that it does not become contaminated.
Use only a very small amount on the tip of the swab. You DO NOT want the
swab to have so much that it could drip or run anywhere!
That could be a very bad thing indeed! Use the same method as
you'd use with the condensed breath. You can see the alcohol left
behind by the swab as you move it over the surface. For nasty oil
or other residue, you may need to do this several times. Use a
fresh swab for each attempt. It's all very cheap.
The bit of residue left behind after the Everclear swabbing can be
removed with a followup swabbing with the condensed breath as the final
It has been said on another website about DSLR sensor cleaning that
Canon uses a mixture of alcohol and glass cleaner to clean these
sensors. I cannot verify that. But this brings up the
idea of using various things to clean the sensor filter. My
warning about that would be that if you use the wrong solvent, you may
damage or remove the special coatings that are on the sensor filter.
Pure water and methanol have been shown to be safe on the 20D, and I
no problems using the ethanol from Everclear. That's all I can
say about that.
Anti-Static sensor filters and
NEW: As mentioned
above, some newer cameras with anti-dust features are reputed to have a
tin oxide (or more likely tin-doped indium oxide) coating on the front
surface of the sensor filter. The manufacturers of some sensor
cleaning solvents have come out with newer solvents made especially for
these cameras. I do not know what the new solvents are exactly,
but reports I've read say that the MSDS for one such new "Tin Oxide
Compatible" solvent is mostly ethanol denatured with some methanol to
make it undrinkable.
fact that they've come out with a new product suggests that they have
found some problem with using their other solvent (pure methanol) on
newer cameras. They were recommending the new non-methanol
the Canon 400D, 5D, 1DMkIII, and 40D. Now I see that they've gone
back to recommending the methanol solvent on the 5D. I've read of
problems with cleaning the 5D. Reports have been seen of the
coating on the sensor filter of the 5D flaking off! Speculation
was that the 5D simply used it's "hot filter" coating as the front
surface. That coating may be extremely fragile.
If I had a 5D, I'd be VERY careful using anything to clean its
sensor. They may well be far more delicate than any of the other
Canons. We just don't know for sure.
It appears that the new non-methanol solvents are indicated
for NEW model Canon cameras
with the "anti-dust" features.
So be careful when choosing a solvent to try on one of these newer
cameras. There must be some reason why people are avoiding
As for the scratch resistance of these coatings: I do not
know. It may be more delicate than what we formerly faced
these filters. I recently got a 40D but have NOT done extensive
testing. I've cleaned it twice with the condensed breath and swab
method, and it seems to have worked just fine with no ill
effects. But I DO NOT have the
extensive experience with it that I do have with the 20D.
So take that for what it's worth!
Since the manufacturers of
several cleaning systems are not telling
people to avoid using their methods on these new bodies, I have to
believe that they
feel that the new sensor filter coating is not overly
delicate. Also, a bit of reading about tin-doped indium oxide
coatings indicates that these coatings are sometimes used to increase
the wear resistance of glass. Thus, one would hope that the
coating is harder than glass which would make it less likely to scratch.
But we do not know exactly what this coating actually is, how it is
applied, or whether it might be
beneath some other coatings which might still be very delicate or
which, perhaps, do not stick to it as well as they do to glass.
So the whole assembly might be more delecate or more susceptible to
damage from solvents and rubbing. I simply do not know!
are doing any of this entirely at your own risk, including using the
commercially available swabs and solvents!!
One last disclaimer:
method is not authorized by Canon. According to Canon, you are
only allowed to blow
your sensor off. Be sure to try that first every time. And
if you decide to attempt my method, don't blame me if you damage your
camera. I take no responsibility for anything you might do
with this information. It works for me, and I've done it hundreds
of times on the 20D with no problem. But I have no idea how
else is and I cannot test it on other cameras so I can't assume any
responsibility for your results.
This is probably why Canon only authorizes us to use a blower.
They cannot know if we'll end up damaging our cameras with some other
method so they just leave us with only the blower.
I have read a couple of horror stories of people scratching their
camera's sensor filter using the "normal" sensor wiping methods.
These reports are infrequent but not unheard of. And I've read
bad experiences with the 5D's coating being totally removed! Any
cleaning that involves touching the sensor with anything carries some
Happy shooting everyone! A clean sensor is a happy sensor :)