Maintenance Day: Checking and Cleaning Dust on DSLR Sensor

I always have a designated day in a month where I would carry out some form of "maintenance work" on either my DSLRs or photographs such as cleaning lenses and sensor and backing up my photographs (which include RAW files, Photoshop files and Aperture libraries).

Today, I happened to be checking and cleaning dust on my DSLRs' sensors, which I thought might be great to share my experience with readers.

Before I elaborate on the checking and cleaning process, it is important to take note on the following:

• I only check and clean my DSLRs' sensors once every 5-6 months - it is not something that one should be doing every now and then.
• There is always risks of damaging the sensor or making it worse if you not careful. So you need to exercise caution when cleaning it and only do it if you are confident.
• Do not be overly obsessed to make the sensor 100% dust-free as it is impossible. Cleaning efforts should be "at best" to clean off visible spots that may affect photographs taken.
• The entire process can be quite tedious.
• Make sure the battery of your camera is fully charged before you start any cleaning process

How Does Dust Get Onto Sensor?

The image sensor will collect dusts over time due to the small amount of static charges that built up on sensor each time the camera is used. 

Chances of dust collecting on sensor also increases each time when changing lenses. So it is always a good practice to face the camera in a downward position (i.e. with the lens mouth facing downward) when changing lens, and avoid changing lens in windy or dusty environment.

Even if you do not change lenses as you only have a single lens, dust will still be collected on the sensor over time. Particularly if you have a zoom lens, the zooming action will "suck in" dust particles into the camera body through the gaps on your zoom lens.

How Does Dust on Sensor Affects Photographs Taken?

Dust particles that collect on sensor will show up visibly as a tiny black spot on photographs when taking pictures with a small aperture i.e. F16 or higher.

The picture below shows some of the more visible dust (circled in RED) when taken at F22:

How to Check Dust on Sensor?

Dust on sensor is not visible to naked eyes. I take a photograph using the following steps to check dust on my sensors:

• Create a solid white background on my computer's monitor. This will be the "picture" that will be taken.
• Camera settings is changed to Aperture Priority (AP) mode, F22 and ISO 100. (Note: Try not to set beyond F22 as dust particles on lens may also show up in the shot taken which we don't want to, as we are inspecting only the sensor.)
• Set the lens to manual focus mode and place the lens about 2-3 cm away from the white background on the computer's monitor screen. 
• To take the picture, turn the focus ring on the lens to the closest focus. (Note: Preferably prime lens should be used so that the picture can get as much even exposure as possible from all corners to the center. If you are using zoom lens, make sure it is zoomed out to the furthest before taking the picture.)
• Once picture is taken, open up the taken picture in Photoshop (or your preferred image editing tool) and do an "auto-level". (See picture below)
• Once that is done, the dust particles should show up visibly on the picture when you zoom to 100%.  (Note: The image is vertically flipped on the sensor. This means that what you are seeing at the top of the picture is actually the bottom of the sensor.)
• The next question that come is how bad are the dusts, and whether cleaning is required. Typically I zoom to about 30% to take a look. If the black spots are still visible (big and large), I would probably go on with the cleaning process.

A closer look at how the dust will look like at 100%:

Before Cleaning the Sensor ...

Make sure that your camera's battery is fully charged as the mirror in the body will need to be flipped up, and we definitely do not want the mirror to suddenly snap back down during any cleaning due to lack of battery power. If that happens, you may end up with a huge repair cost for the mirror.

To flipped the mirror, go to your camera's menu setting and search for a "Sensor Cleaning" option. Select it and choose "Manual Cleaning". Once that is chosen, you will hear the sound of the mirror being flipped up. Once the mirror is flipped up, you may remove your lens and start the cleaning process. (Note: Do not turn off the power on your camera as it will cause the mirror to flip back down.)

Important: Once the mirror is flipped up, the sensor will be exposed. Never touch the sensor using your fingers or other objects, other than those materials/tools that are specified to be used on sensor.

Start Off with "Dry Cleaning"

I always start off with a Giottos Rocket Blower to try and see if some of these dust can be blown off. To do so, I face my camera downwards, and blow multiple times at all angles into the lens mouth. With the help of blowing, the law of gravity should pull some of these dust away from the sensor . (Note: Avoid putting the nozzle of your blower into the camera body.)

After I'm satisfied with cleaning/blowing, I put the lens back onto the camera (note: good to blow on your lens before you attach your lens) and turn off the power - the mirror should flip back down. 

I repeat the process of check dust on the sensor to see if the blowing improves the situation. If it does not help much, then I proceed with the "Wet Cleaning"

"Wet Cleaning" Process

I use the Visible Dust Vswabs and VDust Plus cleaning solvent to clean the sensor. I will not elaborate on how to use it to clean as it is better illustrated from the video on Visible Dust website.

It is important to note the following when using the swabs:

• Fair amount of pressure needs to be applied when swabbing across the sensor. Don't be too afraid to apply pressure (not brute force) - the sensor will not break.
• Do not touch or dirty the tip of the swabs before use. 
• Each swab can only be used once (i.e. after swabbing to and fro the sensor once). If you want to clean again, change to another swab.

Once you are done, attach the lens back, turn off power and repeat the process for checking dust. At this point, if the dust situation should improved. Otherwise, you will need to send it in to the manufacturer for professional cleaning.

The picture below shows how my sensor looks after 2-3 rounds of repeated cleaning process. As you can see from the picture, most of the visible dust (black spots) have already been cleaned away - happy :)