Horseshoe Falls and Cormorant, Niagara Falls
Dust happens, and anyone who uses a digital SLR camera will eventually need
to clean their camera's image sensor. You should be aware that when we talk
about cleaning the image sensor we are actually talking about cleaning a
filter that covers the electronic CMOS or CCD element, which is the thing
that actually produces your images. There is legitimate concern about
scratching this filter since any mark on it will show up on every image
captured by the camera, but the dangers are often overstated. The best
chance of scratching it happens when a piece of hard grit gets trapped in a
cleaning tool and is wiped across the filter surface. This is why it is
important to keep all cleaning tools clean and blow any loose particles off
of the sensor with air before cleaning by any method that uses wiping.
Still, this is not rocket science or brain surgery. It takes only a few basic
tools and common sense to do an impeccable job.
Not All Spots are Created Equal
Most spots that are visible on digital images are simply dust of one kind or
another that floated into the camera body when changing lenses, were carried
in on the back of the lenses and body caps, or were created inside the camera itself.
Some of this dust is sticky, like pollen or oily soot particles from diesel
exhaust. Sometimes tiny droplets of excess camera lubricant
find their way to the sensor's filter. Some spots are liquid or
deposits left by evaporated liquid, produced by very tiny droplets like
those that make fog. Still more dust is produced by the camera as its
internal mechanisms wear. Some non-oily dust sticks to the sensor's
filter because it is electrically charged. Some dust, especially larger
particles, can be blown off of the sensor
with air from a bulb type blower but some cannot. One thing most spot causing contaminants have in common is that the particles are
very small. In most cases they are too small to readily see with the unaided
eye. A typical digital SLR image sensor has well over 3500
pixels per linear inch, so it does not take a large particle to
block light from a few pixels. This is also why even a very small scratch on
the sensor cover glass is something to be avoided.
Checking for Sensor Dust
Checking to see whether your sensor needs cleaning is simple enough. The following method works indoors at night,
where you will most likely be when cleaning your image sensor. Attach a relatively long lens to the camera,
focus the lens manually at infinity, stop it down to its smallest aperture, set the exposure compensation to +1 stop,
and photograph any nearby solid white or light colored surface. A laptop screen displaying an all white full screen
image works very well, but even a piece of paper or a wall that is reasonably well illuminated will do. The surface
being photographed should be no more than a few feet away. The idea is to make the item being photographed extremely
out of focus so the only details in the final image will be dust spots and not features of the item being photographed.
The small aperture makes the light rays between the back of the lens and image sensor parallel to one another and
perpendicular to the glass sensor cover. That causes any dust on the glass cover to cast more distinct shadows on the
image sensor. The long focal length makes it possible to assure the image is completely out of focus at the lens's smallest
aperture, which would be impossible with a very wide angle lens. The long focal length also makes it possible to use something
small and evenly illuminated as a test subject. After this is done view the test image on a computer at 100%
(actual pixels) magnification. Just remember to flip the image vertically so
everything is oriented properly. What you now see is the maximum possible amount of dust you will see in any normally processed image,
with the spots positioned as they are when you look at your image sensor
through the camera's lens opening. Unless you just finished cleaning the
camera you will always see some, so it is a judgment call as to whether
there is enough to warrant cleaning the image sensor. Some use "Auto Levels" in Photoshop to
make dust spots stand out even more. I do not because the extreme contrast
boost shows spots that would be never be visible in a normally processed image. If I am in the field
photographing wildlife I sometimes make
an additional exposure as described above, but at a wider aperture like f/8 or f/11. Since wildlife photographs are typically
taken using large apertures, this additional test image gives a more realistic idea of whether spots I see in the first test image
will show up in the my photos. The smallest spots visible in a test image made at, say, f/32 will be invisible at f/8 or f/11.
Likewise, many of those visible at f/8 or f/11 vanish at wider apertures.
I should also mention that I think direct visualization is not the best
way to find tiny particles when cleaning an image sensor, which is why I
never use it. The method above is easier, provides more
magnification, and above all it gives a more realistic idea of what the particles
can do to an actual image. That's what really matters.
Getting Carried Away
As with many things it's easy to get carried away and spend a fortune on
cleaning tools and magical cleaning solvents. Back in May of 2004 a company called Visible Dust
introduced a line of static-chargeable sensor cleaning brushes. They were priced at $34.95
until later the same year when the price suddenly increased to about $100. Visible Dust
was using photos of plasma
chambers and talk of DNA and biochip technology to sell what was just a simple
wood handled brush for
an insane price.
Really. Today they offer countless pricey high-tech items to help perform the
basic low-tech task of cleaning your camera. These include
motorized twirling sensor brushes
with headlights, no less than five different task-specific solvents and
oodles of color-coded task-specific swabs and brushes to go with them,
lunar-module-like sensor loupes, and a $50 "Anti Static Property Dust
Free Ejection Projectile Free" bulb blower. Holy dust particles Batman!
These folks are really
cleaning up (pun intended) on the anxiety that exists over cleaning
SDLR image sensors. While there is nothing specifically wrong with these products I think
they give new meaning to the phrase "marketing hype" and "overkill". A few
basic items will keep your images just as spotless for hundreds of dollars
less. Specifically, you need a good
bulb-type blower, simple but high quality brush, a solvent cleaning tool
with pads and a solvent to go with it. All of that will cost about $70, and
it's all you will ever need to clean your camera's image sensor.
Cleaning with Blowers
Blowing the sensor off with a clean hand operated blower is the safest method, but it
can remove only loose dust that is not stuck to the sensor. This cleaning
method works well enough to get us by for a few weeks on location, but
it does not do a thorough job of cleaning. In addition to not removing any
debris that are stuck to the image sensor, it can add or simply move dust
around on the sensor unless you do it carefully. It is best to mount the
camera on a tripod with the lens opening facing directly downward so
particles tend to fall away from the sensor and out of the camera when the
sensor is blown off. This position is somewhat awkward, but one gets used to
it quickly enough. This method never produces a completely dust -free
sensor, but a few small specks on an image are no big deal. Depending on
the shooting aperture, they may be completely invisible. In the worst case,
cloning them out in Photoshop is quite easy. Given that, if you start out
with a clean image sensor there's not much reason to carry more than a
blower when traveling, unless you'll be gone for more than a few weeks. It's
also a good idea to blow any
loose dirt off of your image sensor before cleaning it with any other
method. That safely eliminates any larger hard particles that are most likely to
scratch. I like the Giottos large (model AA1900)
Rocket Air Blower
which can be purchased at many camera outlets including
for about $8. It's a good idea to keep any blower in a tightly sealed
plastic bag so it stays clean.
Cleaning with Solvents a.k.a. Wet Cleaning
This is always, or nearly always, step two in my sensor cleaning regimen.
Cleaning with a solvent using what's informally known as the Copper Hill Method removes every spot of every type,
It is also cheap and relatively easy once you learn the technique, though learning it takes a little practice. We have cleaned all of our image sensors
this way countless times over nearly a decade and it has never caused even
a minor problem. The Copper Hill Method uses a simple tool called
the "Sensor Swipe" which can be purchased in a
Copper Hill Images
for $29.95 plus shipping at the time
of this writing. The kit contains everything you will need for solvent
cleaning and the Copper
Hill website has detailed
on the use of these products. Essentially a "QuikStrip" or
Pec*Pad is a piece of disposable, lint-free cloth that is attached to the "SensorSwipe" and
then moistened with a couple drops of Eclipse solvent.
The tool with the moistened cloth attached is then used to
clean the camera's image sensor. It's simple enough. Eclipse optical glass cleaner
is the key to this process because it leaves absolutely no residue or streaks,
and it's the only sensor cleaning solvent you need. Note that the Basic Kit
I mentioned comes with your choice of either QuickStrips or Pec*Pads.
QuickStrips are like Pec*Pads but made to fit the SensorSwipe. QuickStrips
are therefore more compact and convenient than wrapping the larger Pec*Pad
multiple times around the SensorSwipe tool. Never cut down a Pec*Pad because
cutting will produce tiny pieces of fiber and you are
very likely to contaminate the pad with dirt and oil from scissors and
fingers in the process.
Eclipse solvent and Pec*Pads are made
by Photographic Solutions and can be purchased at
Copper Hill Images
, and elsewhere. The SensorSwipe and
QuickStrips are made by Copper Hill Images and as far as I know can be
purchased only at Copper Hill Images
The Copper Hill sensor cleaning method has worked somewhat better for us than the much more expensive
, which are both good products produced by Photographic Solutions. This seems to be because the wiping
surface is more evenly and firmly supported across its entire width by the Copper Hill Sensor Swipe. The only problem I have encountered with the Copper Hill Method is that
the required and flammable Eclipse solvent cannot be transported on commercial airlines.
Photographic Solutions may
have solved this problem by offering
" that include a 0.5 ounce bottle of Eclipse solvent.
Unfortunately the regulations involving carrying things like flammable solvents are
not clear. While
they seem to exempt quantities of 0.5 ounce and less, the exemptions
apply only to things like butane lighters and medical items, not cleaning
Solvent Cleaning Product Concerns
You'll notice that Photographic Solutions warns against using Pec*Pads
for cleaning image sensors, and that they provide no warranty if Pec*Pads used
for this purpose cause damage. They also say that Pec*Pads are safe to use on film emulsion, which is quite soft and scratch prone, mirrors, telescopes,
and lenses. The obvious question is why something that will not damage film emulsion, mirrors, telescopes, and lenses might damage the filter over the
image sensor in your camera. Fortunately, David Stone of Photographic Solutions took some of his time to explain this to me, and it boils down to two basic
1. The safety of Pec*Pads has not been tested with respect to image sensors, but it has been tested with respect to film emulsions.
2. Cleaning a camera's image sensor requires much more handling of the Pec*Pad than it requires handling of a Sensor Swab, so the risk of contaminating the
Pec*Pad with abrasive dirt or oily fingers is much greater. Since Photographic Solutions has no control over how the
Pec*Pads are used, they discourage their use for
cleaning image sensors.
all fair enough. These products are used under all sorts of circumstances by people with various levels of understanding and skill.
I would not guarantee the use of either one! I just prefer to assume the risk and save the money,
which has not resulted in a single problem over nearly a decade. Sensor Swabs are
about $3.75 US
each and Sensor Swab Plus is about $5.00 US each while Pec*Pads are only $0.09
Since it often takes more than one of any of these for each cleaning the
difference is even bigger than it seems. If you
infrequently clean the image sensor on a single camera
and doing it stresses you out, the Photographic Solutions Sensor Swabs may make
To stay out of trouble using the Pec*Pads we always:
1. Work in a clean area.
2. Remove a pad from the factory packaging by gripping its corner with a clean pair of tweezers.
3. We wear new powder-free latex gloves in handling the Pec*Pad. These are available at any drug store.
4. Follow the Copper Hill instructions to the letter, and do not cut or trim the
5. Once out of the package, do not let the Pec*Pad touch anything except the sensor until after it is used.
Sensor Cleaning Brushes
The principal by which static-chargeable brushes work is simple. Certain materials, like nylon or
hair, have a tendency to accumulate a static electrical charge when rubbed
against certain other materials, like paper or even air moving at a
high speed. The bristles of sensor cleaning brushes are made of such a
material. To charge the brush you blow air through it with the same
bulb-type blower I already described above. Once charged, the
brush is very lightly passed over the surface of the image sensor in your
camera. The static charge in the bristles makes any dust particles
encountered stick to the brush instead of just being pushed around by it.
The only trick involved is to never let the brush bristles touch anything
except the sensor. There is oil present in and on the mechanisms surrounding
the image sensor and if you get oil on the bristles you'll have a mess on
your hands. It's not the end of the world, but it will take a few cleanings
with a solvent. also described above, to fix the mess.
Brushes with static-prone bristles and insulating handles have actually been around
for as long as there have been brushes. It's possible to source one yourself
from a cosmetics shop or artist supply store, but that's not very practical.
The brush you end up with might cost only a couple dollars but you'll spend
$100 and a lot of time finding the right
one. For more
detail see this
about sensor cleaning brushes.
The only static-chargeable brush I can recommend is the high quality
brush sold by
Copper Hill Images
for the very
sane price of $27.95 plus shipping in August of
2013. They ship
quickly and the brush comes with a dust-tight carrying tube and
instructions. It's simple, cheap, and effective. Static-chargeable brushes are a handy option that I wouldn't be without,
but I use them
only for cleaning any dust specks that remain along the edges and corners of an image sensor
after wet cleaning. That avoids smearing oily deposits and contaminating the
brush. If the Copper Hill SensorSweep seems too low-tech I'd suggest taping
it to one of
and naming it the Tropical Caterpillar.
Using a static-chargeable brush to clean your
camera's image sensor has potential advantages when it comes to air travel
because they are used dry and require no flammable solvents. As I mentioned
previously, they are
particularly useful for cleaning up the few nits that remain in the sensor's
corners and edges after wet cleaning. Static-chargeable brushes alone can remove
most or even all particles from an image sensor, and they are not likely to
scratch. The real problem with these is that if you brush over an oily
particle you will create a large streak. The brush will also be
contaminated, making it possible to create more streaks before you realize what
happened. If this occurs when there is no way to clean the sensor with solvent you
are worse off than if you had not cleaned the sensor at all. Since one can
never know when or if this situation will occur I
hesitate to use a static-chargeable brushes if there is no access to
solvent-based cleaning tools. In fact I use a brush only after a solvent
negates the potential air travel advantages of the brushes for me, but it
also prevents me from being out in the middle of nowhere with a big streak
across my camera's image sensor.
One last thing to remember is that
moisture in the air is a good conductor of electricity and it tends to let
electrical charges neutralize themselves quickly. Any static-chargeable
brush will perform better in dry environments than in humid ones.
I first used the original
cleaning device long before digital cameras existed. Their performance in cleaning hard to reach
rear lens elements and nasty fingerprints from any lens element when you’re out in the field is astonishing.
When I found out about the LensPen
product for cleaning digital camera image sensors I thought it might be
exactly what's needed when air travel is involved because, like the static
chargeable brushes it requires no flammable cleaning
The good news is that the SensorKlear picked up all the particles I saw when I initially checked the sensor at “actual pixels” (100%) in Photoshop, as
described previously. The bad news is that it replaced them with loads of extremely
everywhere the SensorKlear had touched the image sensor cover.
These could be seen only at “actual pixels” (100%) in Photoshop, and they were smaller and more numerous than I’ve ever seen on my sensor before. These
were definitely not present before I used the SensorKlear. I used the SensorKlear again in these areas but it only moved the particles around or added more.
After deciding that the SensorKlear was not for me, I used several wet cleanings followed by the Copper Hill brush to get a perfectly clean sensor.
I may have been able to do this with only the brush, but I didn’t want to pollute
my brush with the extremely fine dust.
I have a few educated guesses about all of this, but I don't intend to do any experimentation to prove or disprove them. First,
because checking is done at
f/32 with the lens focused at infinity so it's a worst case scenario. The tiny specks might not be seen at all
when using more reasonable apertures like f/8 or f/11. Second, even if they
were still visible at 100% (actual pixels) in Photoshop they would probably
not be visible even in reasonably large prints. In the end the fine particles deposited by the SensorKlear might be
too small to matter, but I'm not taking that chance. The usual pieces of crud found on image sensors can be cloned out of an image
with relative ease but the particles I found after using the SensorKlear
were far too small and numerous to
be readily cloned out. I simply
don't like the idea of having ultra-fine particles all over my image
sensor. I've heard that one can lessen these
particles by tapping and gently wiping the SensorKlear cleaning surface on a clean Pec*Pad multiple
times to get rid of the excess particles. I'm not going to try this but you
are welcome to. I'll even update this article with your results if you let
me know. The bottom line is that tiny particles were definitely deposited by
the SensorKlear and it's
very obvious that other
cleaning tools and methods produce a cleaner image sensor.
With all of that said, the particles deposited by the SensorKlear on my
image sensor are far too small to matter on a lens element. They would never be seen
in a photograph under any circumstance. That's why I will continue using
the original LensPen on lenses in hard to reach areas of lenses as needed.
Image sensors are a completely different matter and cleanliness there is
much more critical.
Just for the record, the LensPen SensorKlear I
used was new and used for the first time in the events described here. The
camera used was a Canon EOS 1Ds Mark III. I followed all of the directions
that came with the SensorKlear and took the same cleanliness precautions I
always take with any cleaning method. Those are described above.
Vibrating Self-cleaning Image Sensors
These gizmos may buy some time between manual sensor cleanings but none work
well enough to eliminate periodic and thorough manual cleanings.
Frankly, cleaning an image sensor isn't difficult enough to justify the
complexity and expense of a contraption that works so imperfectly.
Because everyone freaks out over the sensor dust issue, Canon and others
offer self-cleaning sensors as a marketing tool even though they work poorly
and manual cleanings are still required. Of course the marketing literature
doesn't say that.
Because these vibrating gizmos cannot possibly
remove all of the dust, Canon has also developed software
to remove spots created by dust that remains on the sensor. I see this as a
rather lame method in principle. One has to take a picture of a plain white
surface with the lens focused at infinity to create a dust map so the
software knows where the dust is located. But, every time you turn the
camera on or off, the vibrating gizmo does its thing, which can move some
dust particles and make the dust map inaccurate from the start. Also, any
dust that finds its way to the sensor after the dust map is made will not be
part of the software's "map". Obviously, a single dust map image cannot work
for processing a couple weeks worth of images from a remote location after
one arrives home. It will remove some spots, but not all. Further, the size
of dust spots in images varies with the aperture used to shoot a given
image. Using one test image to remove dust from images shot at varying
apertures is a compromise at best. All of this sounds like a lot more hassle
than just cleaning the sensor!
When it comes to sensor cleaning
it turns out that the simplest and least expensive methods are still the most effective.
A good sensor cleaning kit is cheap and it will keep your images
just as spot-free as the latest spaceship-inspired whirligig. For a very
complete kit I'd suggest a
Large Rocket Blower, a Copper Hill Sensor Sweep brush
Copper Hill Sensor Swipe with QuickStrips,
and a bottle of Eclipse solvent
, all for a grand total of
about $70 plus shipping. When your camera's image sensor needs cleaning
start by blowing it off, follow with a wet cleaning, and finish up the
details with the brush. That's what we do and it works like a charm. We typically clean a camera after a two or three weeks of
fairly heavy shooting. Between cleaning maintenance can be done with only a
blower, but depending on conditions it's not often necessary. If a few spots
sneak by they can be easily handled in post processing.
Happy sensor cleaning,