To address your direct question: Can you clean this at home without damaging it?
The answer is yes ... and it's not difficult. There are many videos available on how to do this. But I'll address a few basics.
Anytime you remove the lens and the body is "open", there is an opportunity for dust to enter. Of course the shutter is closed, so that dust can't land on the sensor. When you take a photo (especially long exposures), the reflex mirror quickly swings up and this creates a whoosh of air in the body which disturbs the dust -- sending it floating randomly and... at this point the sensor is open so there's a possibility it will land on the sensor (and the longer the exposure, the greater the probability.
What we think of "the sensor" is actually a couple of filters in front of the sensor. (Two layers of glass, then the sensor). The front layer is typically the UV/IR filter and this is wired to a circuit that generates a piezoelectric charge -- vibrating the filter to shake any dust loose (this is what happens when the sensor does a self-cleaning cycle). The back layer of glass is a low-pass filter which helps with some anti-aliasing to reduce the moire effect that might otherwise be visible when shooting subjects that have strong linear or grid-like patterns.
This means that when you think of cleaning the sensor, what you're really cleaning is a filter in front of the sensor. The filter is glass (glass with coatings on it, but still glass). Glass is pretty hard ... so as long as you don't use something abrasive, the probability of scratching it is actually pretty low. It also has those coatings ... so you don't want to use any cleaning chemicals that might damage the coatings.
There are "dry" and "wet" cleaning methods and often a "dry" cleaning method is good enough.
- In a clean (low dust) environmnet (wipe your kitchen table clean and use that) remove the lens, point the camera toward the ground and run a self-cleaning cycle. This way if the dust does manage to fall away, it will leave the camera body and fall toward the floor.
With each step, you can test the camera to see if you cleared the dust. Put the lens on it. Switch to Av mode and dial in the highest f-stop available for your lens (e.g. f/22 ... or f/32 if the lens supports it). This creates a tiny pin-point opening in the center of the lens which will produce better shadows (dust shows up better at high f-stops ... and may not be noticeable at low f-stop values).
You don't actually need to focus the lens ... just point the camera at featureless spot like the blue sky ... or a plain white wall, etc.) and snap a photo. It isn't the wall or sky that we want to focus... it's the dust. The dust is focused by using the highest f-stop your lens can provide.
When you no longer see any dust spots ... you're done. But if you do see dust spots even after a self-cleaning, then continue.
- You can also get a hand-squeeze air bulb to blow puffs of air into the camera to attempt to blow the dust free.
Navigate your camera's menu to find the manual sensor cleaning option. All this does is raise the reflex mirror, opens the shutter, and it powers off the sensor. It will remain open until cancelled or until you power off the camera.
Just use a hand-squeezed blower (such as a Giottos "Rocket" blower). Do not use cans of compressed air. This is because the propellant used in the "air" cans will produce a foggy residue on the sensor that wont clear up on it's own and then you will need to wet-clean the sensor. There are apparently versions of compressed air that claim to be residue-free but I have not experience with them.
As you blow the puffs of air on the sensor, avoid letting the tip of the air-bulb touch the sensor or any internal parts (touch it only with air).
Test to see if the dust is still there (as described in step 1). If it is still there, continue.
- There are a number of direct-contact cleaning devices meant to clean the sensor. A simple artists paintbursh (very soft bristles and preferably never touched so as to avoid getting any skin oils on them ... it should be pristinely clean. Any residue or oils will only make the glass surface more "sticky" to future dust). You can gently brush the sensor to knock the dust free.
There are special-purpose brushes for this that have a grounding wire. The idea is that if the dust has a static-charge (and that's why it's "sticking" to the glass), the grounding wire in the handle (with conductive bristles) will release the charge so the dust can fall free.
There is a product (I do not recall the name) that is basically a stick with a gummy tip. You gently daub the gummy tip on the glass (you don't slide it) and the gummy material is "sticky" to the dust, but doesn't actually have any residue (so when you pull it free, the sensor is completely clear).
As in previous steps, test to see if the sensor is clear.
- If the sensor still isn't clear, whatever is on the sensor may be stuck rather well (such as a drop of oil-splatter). I'm not aware of any Canon bodies that had this problem (Nikon had one particular model that was notorious for this) and this requires "wet" cleaning.
The popular lens cleaning solvent is something called "Eclipse" cleaning fluid and it's made by "Photographic Solutions, Inc.". The solvent is basically near-pure methanol. It is applied with a special swap they call "Sensor Swabs". It just takes a few drops (as in 3 or 4) on the swab. The swabs come in different widths based on the sensor size (they make swabs for full-frame camera, APS-C crop-frame cameras, etc.) so you'd want to get the correct size swab. A few drops on the swab and then gently give it one continuous wipe all the way across the sensor from edge to edge.
The methanol will likely break whatever bond is holding the spot and it'll get picked up by the swap. The reason they pick methanol is because it evaporates VERY quickly and leaves virtually no residue behind. You get a pristinely clean sensor.
Again ... there are videos that demonstrate many of these techniques and products. The surface you are cleaning is actually a filter in front of the sensor and it's glass and as long as you don't go at it too aggressively with harsh chemicals or abrasive tools, it is difficult to scratch it (so you don't need to be too afraid to clean it). Dust getting on the sensor is a fact of life ... from time to time sensors need to be cleaned. Many camera shops will clean the sensor for you .,.. for a fee. You may as well learn to do it yourself since it really isn't difficult.
Tim Campbell
5D III, 5D IV, 60Da
