Dirt happens. Even if you take ultra-good care of your camera, never changing lenses near dirt or dust, or in windy conditions, your camera sensor will eventually get dirty.
How to See if Your Camera Sensor is Dirty
Testing your sensor for dirt and dust is very simple – you basically take a picture of the sky at a narrow (fine focus) aperture.
The steps listed are for taking the picture in manual mode, but you can also use aperture priority.
- Go out on a fairly clear day (low amount of clouds) with ISO set to around 200
- Change your file type to raw – if you are familiar enough with Adobe Camera Raw converter
- Put your aperture (f stop) to around 16 or 22
- Expose for the blue sky (move the little tick marks so they are under the middle tick mark or zero in middle of number line you see when looking through the view finder)
- Focus on something like a nearby tree, then move your camera to the sky without losing that focus (meaning don’t let up on the shutter if you’re focusing that way)
- Click/release the shutter to take the picture (it should be a nice all or nearly all blue sky)
- If the image is too light/bright, speed up your shutter speed and take the picture again
You may not be able to see the dirt just yet. We need to get the image onto the computer and see it enlarged.
- Import/upload your image however you normally do
- If in PSE/PS, open the raw file in ACR – move the clarity slider to the right to define the specks of dirt and dust
- If in Lightroom, do the same as above (move clarity slider to right)
- If the image is a JPG and you’re using PS/PSE, you can do a Brightness & Contrast adjustment and bump up the contrast, which will define the dirt and dust more
If you saw a lot of dirt on your sensor that you’ve never seen there before you might be wondering why. Why haven’t you noticed this before? The answer is simple – we seldom shoot at such a narrow aperture (f16, f22) unless shooting landscapes and we seldom just shoot a blank sky. There were people, trees, buildings obscuring the dirt.
Also, many of us shoot our subjects with a wide aperture, meaning a small f number like f2.8 or f3.2. This causes the background to get blurred, so all those little dirt and dust specks were blurred away.
How to Keep Your Camera Sensor Clean (as possible)
If you have a newer camera you might be wondering how you can keep your sensor clean for longer, how to prevent it from getting so dirty. There are a few things you can do to keep dirt to a minimum.
- Never change lenses in a dirty/dusty environment like a beach (or while sitting in a sandbox with your child)
- If you are in windy conditions, turn so that your body is blocking the wind before changing the lens
- Keep your camera body and lens’ end pointed down during the change (when it’s facing downward, less likely that dust will settle in it)
- Turn on the sensor cleaning that is likely an option on your camera (most cameras that are 3 years old or newer have that option)
How to Get a Dirty Sensor Cleaned
Now that you know your camera is dirty, what do you do about it? One thing I am NOT going to do is tell you to try to clean it yourself. If something should happen, I do not want anyone coming back to me and saying “You said it was safe to clean it and now look what happened!”
What I recommend is that you send it to a professional for cleaning. That is what I will be doing. I have my box and my Nikon D700 will be heading to Nikon USA to get spiffied up after the upcoming Prime workshop in mid-September.
If you have a camera that is a six months old or newer, you may do this test and find nothing. That is not uncommon because the camera is still new and you haven’t had time to expose it to as much dust and dirt as those with older cameras. My Nikon D700 is two years old and the above image is from my camera.
Have you done a sensor test before? Were you surprised by the results? Or, if you try this test, come back and let us know what you find.