Dust is all around us. As photographers we have to encounter dust every day. Cleaning an image sensor is one of the skills every photographer should master. Even if you are shooting inside a relatively controlled environment such as a studio or an office, a little bit of dust is always going to be a part of the equation. Dust and image sensors do not mix well together. Although many new bodies are being marketed as weather-sealed, they are not technically 100% weather sealed. If you stop to change lenses, you expose your camera to dust, dirt and other elements. Additionally, when a lens zooms in and out it sucks in air and with it dust (the cheaper the lens the greater the possibility). This dust settles inside and outside the lens, as well as on the internal parts of the camera.
If dust settles on the rear end of the lens the effect will be visible on the image. This can be easily cleaned with a lens cleaner brush. The same goes for dust that’s settled on the front element of the lens. This is the easy stuff. Problems arise when dust gets through to the inside areas of the camera, such as a mirror and most importantly on to a sensor. These require special cleaning regime to get rid of.
How do you know that you have dust on the sensor?
If you continuously notice that your images are having spots on them and that the spots are consistently at the same position, you have dust on your sensors. Sometimes though, due to the aperture that you are using the spots may appear non-existent (at bigger apertures) or sharp black dots (at smaller apertures). This is yet another indicator that you have sensor dust and it is not something that is on the viewfinder or the mirror or the lens front or rear elements. Why? Because, if and only if the dust is on the sensor it will appear blurred out to the extent it is almost negligible when you are using a larger aperture and smaller and more distinct when you are using a smaller aperture. If you already have photos with sensor spots and would like to get rid of them in post processing, check out Quick and Easy Sensor Spot Removal tutorial.
If you want to check exactly where sensors spots are, switch to aperture priority mode, dial aperture as narrow as possible (preferably above f/8), switch to manual focus and push focus to infinity (or just defocus). Then take an image of clear sky, blank piece of paper or even a blank white monitor and if there are any sensor spots, they should pop right out.
So what does dust on the mirror look like?
If you are shooting with a DSLR, there is a mirror sitting between a lens and a sensor in order for you to see through the viewfinder what the sensor will see once the shutter is pressed. Dust on the mirror is definitely less worrisome, meaning it is not going to affect the quality of the images. You will only notice them when you are composing through the viewfinder and not when you are composing via the back LCD. When you take the image there will be no spots or blotches on your photos. Unless you are really bothered by the dust on the mirror there is no urgent need to get rid of that.
So what does dust/dirt/grease on the lens looks like?
Dust, dirt or grease on a lens will make your images lose contrast and color. When reviewing an image you will notice a certain area of the image will appear less sharp or with botched up colors. This usually happens, when you have left a finger impression on the lens or when the front glass element is dusty.
How to clean an image sensor?
In the heart of a DSLR, sitting right in the middle of the camera is an image sensor. It is the most important part of any camera and not just a DSLR. Mirrorless cameras are actually even more prone to dust settlement of sensors because their sensors are completely exposed to elements when a lens is removed (without the protection of a mirror). Image sensor captures light and converts it into electrical signal for further processing. It is an extremely sensitive element, so be very careful when attempting to clean it. If you are unsure, just send it to a professional servicing store or your camera manufacturer and let your image sensor be cleaned by professionals. If done incorrectly, you can seriously damage the sensor and consequently render the camera unusable. Otherwise, if you are determined to clean it yourself, follow the steps below.
Before we move on, note that most DSLRs come with a self-cleaning feature. Nikon DSLRs have an option that says, “Clean Image Sensor”. If you are a Nikon user go to Setup Menu to access this. Canon users can look for “Sensor Cleaning” option in the menu. This feature should take care of smaller and less stubborn dust particles.
Steps for stubborn hard-to-get-rid-of dust particles:
Step 1 – Acquire a good cleaning kit. There are many good DIY cleaning kits available on amazon for cleaning your camera sensor. Always pick the one that has a good rating and gives you all the tools that you will ever need. These include bulb / rocket blower, can of compressed air, cleaning brush, swabs and solvents / wipes.
Step 2 – Set your camera to “Lock mirror up for cleaning” mode. Again, this is as for Nikon DSLRs. Canon users will have to go to Sensor Cleaning option in the Menu and select “Clean Manually”. This will lock the mirror up and exposes the sensor for you to clean. Before attempting to lock the mirror, check how much juice is left in the battery. If there isn’t enough power the camera will not allow you to lock it. Worse, it may drop the mirror when the battery is exhausted. If you are still cleaning the sensor this can damage the delicate internal parts. So don’t prolong your cleaning exercise once the mirror is up.
Step 3 – Use a rocket / bulb blower. These are manual blowers that has a small air vent attached to a rubber bag that you squeeze to push air into your camera and blow off any dust particles of the sensor. A good way to do this is by holding your camera upside down so that as you blow air and when the dust particles are dislodged they fall right down and don’t get resettled inside. Use the blower away from camera a couple of times to make sure any dust inside the blower is out and that there is no moisture there. I once has a little water residue in the blower which ended up all over a sensor. Making it a bigger problem than what I started with.
Step 4 – Use a can of air. For dust particles that are less co-operative a can of compressed air is a much better solution. As with the blower, try out to use the can of air away from the sensor initially. Sometimes when the can is too cold the cool air will create condensation in a warm surrounding. Some experts often claim that a cotton swab is a better tool, but in my experience this isn’t the best approach. The less you touch the sensor the better. If you happen to touch the cotton swab accidentally before you touch the sensor you can transfer additional grease and dirt onto it. A can of air will ensure that you don’t touch the sensor and still get rid of any stubborn dust particles. One thing to note is you shouldn’t hold the can of air upside down when cleaning. Neither should you direct this towards exposed skin on your body. These cans have propellants which are very toxic. Additionally, these cans when fired upside down often releases the cooling elements inside them which can instantly freeze the surface they come in contact with. For your camera sensor it can be lethal. Make sure you wear protective glasses when using these as accidental releases directed towards your eyes may cause serious damage.
Step 5 – Use special wipes / swabs.
There are special wipes / swabs available on the market that are smeared in a chemically enhanced solution that can help with cleaning. These wipes can be used for really stubborn dust that grips on to the sensor surface. Gently wipe the surface of the sensor in one fluid motion and stop. Then double check if the dirt is gone. If not, do another single motion over the entire sensor. Once your sensor is clean, enjoy your photos without any annoying and distracting spots.