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Many things are told
about image sensor cleaning. If some of them are true, many others are
dangerously wrong. Here the most important
thing to consider is that the sensor
surface is an optical surface, and therefore should be treated as well. In
fact, this is the surface of a band
pass filter which stops the excess or
infrared radiations, and then only the visible light waves are able to reach
the sensor. The sensor is made
of millions of phototransistors initially far
more sensitive to infrared than visible light. So, this band pass filter is
used to bring images to natural
colours.
Below, the sensor of a Hasselblad camera, a second one from a bridge
camera, and a smaller one from a standard video camera, a handheld
of about $ 40,000.00 !
Some advice:
Compressed air:
First thing to know about cleaning is to avoid the use of any compressed
air or compressed gas canister of any kind, whatever anyone tells you.
In fact,
the very high velocity of the gas mixture will, by ventury effect, bring close
particles in air to propel them at a very high speed to the surface,
acting as
a sandblast to your optical surface, and therefore doing unrecoverable damage.
Dry cleaning:
Never ever try it. Obviously, we can understand that when two surfaces are
touched together, they have (at the least a molecularly) abrasive
effects to
each other. For optical cleaning work, we always need to use a gentle solvent
such as isopropyl alcohol which will act either to dissolve
the dirt as well
act as a lubricant between both surfaces. Do not use methyl alcohol or methyl
hydrate; this solvent may damage the multi coating
on the optical surface.
Reusable tools:
Some techniques involve to reuse the cleaning swab many times, also, some kind
of pencil are sold on the market which have a brush on a end and
a kind of
leather pad at the other end, this is the worse case because when the leather
swab being contaminated by dust or sand by a previous usage,
theses particle
will scratch and damage the optical surface on future uses. It is exactly like
reusing your toilet paper!
On all of your photo equipment, your image sensor is the optical surface on
witch a mistake will have the worst consequences. Unlike some of our
competitors, our proficiency was not acquired by luck or by chatting on the
internet; our skills and competences are acquired from technical training
at
the head offices of great manufacturers such as Hasselblad and the Carl-Zeiss
factories, making our expert advise the most reliable at the same
cost. So,
when you hear weird comments, don’t hesitate and contact us for our opinion, it
is free
Where are those dusts particles?
As we can see in the drawing below, there is the lens on far right which, on it
optical axis, will produce an image to be reflected toward the focus screen
by
the mirror. When we take a picture, this mirror will move up as the shutter
opens, allowing the lens to project its image on the image sensor after being
filtered by the band pass filter which will stop the excess of infrared light.
When the observer is looking through the eyepiece and sees some dusts, theses
dusts particles are not on the image sensor but on the focus screen or on
the
reticle or on both and therefore won't be visible on pictures. If you think
that theses dusts particles are on your pictures, this is because, by accident
some dusts particles are also at the same time at a geometrical similar place
on the image sensor but they are not the same. Same thing for the mirror, dust
on the mirror cannot be seen either by the observer or by the image sensor. So,
if they are dust on your pictures, theses dust particles do not come from
the eyepiece
or from the mirror. They are located directly on the image sensor, in fact on
the band pass filter which is directly deposed and sealed above
the image
sensor and that is this surface we are cleaning when needed.
Auto and self cleaning sensor:
Manufacturers
have recently introduced self
cleaning sensors which mean that every time you replace the lens, or
simply activate this function by menu, a
device produce ultrasonic vibrations
onto the filter on the surface of the sensor. This system work well with a dry
surface but after a while you still need a
manual cleaning due to the surface
to become sticky with dust. It is like your house windows, after a recent
clean, a slight blow can remove the dust from
it but after a many months
however you would shake your windows or blow air on it, the dusts particles
will still on the surface.
Below, the vibrating plate with it piezo electric device and the band pass filter.
Cost:
For sensor cleaning, the cost start from $30.00 and the
job is done in about 5 minutes. But, if you have just purchased your new DSLR
camera from within
the last 6 months, then, we will do the first sensor
cleaning for free just bring your proof of purchase. However, it’s a good idea
to call before coming
to our office to make sure a qualified technician is
available. Also please be sure the battery is fully charged and your camera is
at room temperature
and not frozen. Coming from a cold car in winter time the
dew forming on the cold sensor and mirror will make it a lot more difficult to
clean we’ll just
have to wait till it warms up.
How do theses dust particles can get in my camera?
Can you immerse your camera under water? No? It is because your camera is not
water and dust tight. In fact, if you take off the lens and gently blow
air by
the data card compartment, you will feel the air with the back of your hand
placed at the front of the bayonet mount. Also, any movements of the
lens for
focusing or zooming involve a front and back displacement of many lens
elements inside the objective, acting as a bicycle air pump, blowing air
from
outside to inside and vice versa.
So, you can find some dusts particles even a few minutes after a clean. Just the
action of taking a picture will make the shutter's blades shake and cause
some of
remaining particles between them to be released and cause theses particles to
fall on the sensor. Of course at each cleaning we do many shutter
releases to
remove as much as possible the remaining particles from the shutter we also
verify our work with white defused light.
We do not recommend that you try to clean a sensor by yourself. Bring it to us,
for professionally executed and carefully done job, you and your camera
will be
happy you did.