Sensor Dust Detection

If you are using a Point and Shoot camera (one you can’t change the lenses on) then this post won’t apply to you.  But if you think a DSLR might be in your future, this will be something to consider.

Sensor Dust is the bane of a DSLR.  It shows up as circles.  It gets on the sensor when we change the lens.  It is can usually be removed with the newer cameras which have auto dust of features which can be activated from the camera’s menu.  Rarely does the sensor itself have to be touched.  DON’T EVER TOUCH THE SENSOR.

We are going to talk about how to find out if you have dust and a simple way to remove it 99% of the time.

Sensor Dust Detection

Blue Sky.  The best and quickest way to detect dust on a sensor is to walk outside point your camera at a blue sky and take the shot.  Blue sky for some reason really shows off sensor dust.  It always shows up as dark circles.  You can see in the photo above the dark circles.  Expand the image to see it full size.  Those circles are small specks of dust on the image sensor.  They are almost impossible to find in a photo with lots going on, but a blue sky makes them stick out like a sore thumb.

Removing Sensor Dust

I mentioned above that newer cameras usually have a sensor dust of in the menu.  Selecting this will cause the sensor to vibrate and usually jar small dust specks off the sensor.  But not always.

The method I use most is the Bulb to remove the specks.

The Process:

• Remove the lens
• Select Mirror lock up from the menu
• lock the mirror up by pressing the shutter usually
• Point the opening toward the floor (dust will fall down)
• Use the bulb to blow air on the sensor (usually 10 good puffs)
• while still pointed down shut the camera off (or whatever your camera calls for the drop the mirror back in place)

Preventing Dust on the Sensor

You can’t.  Dust will get on the sensor.  Maybe if you never switch lenses or remove the lens, but even then you stand a great chance of at some point having dust on the sensor.

But you can minimize the amount of dust.  Here are some steps to take to keep dust to a minimum.

1. Use that bulb to blow off the camera each time you take it out of the bag.
2. Keep the camera in the bag when storing it and keep the top zipped shut.
3. When you go to switch the lens blow off the camera around the lens before removing
4. Blow off the back of the new lens you are about to put on the camera before you attach it (this prevents dust riding in on the back of the lens and dropping on the sensor)
5. Use the Bulb a lot.
6. Don’t remove the lens in high wind or dust.

Take these preventive steps and you can minimize sensor dust.  If you have been out on a dusty shoot take a shot of the sky when you get back to check for dust.

But I have sensor spots on my images, what can I do?

Most post production software will have a healing or blemish tool, these work very well to remove sensor dust spots.  I usually set the size of the healing brush to be just a little bigger than the dust spot.  This way I don’t have move the brush, just click it over the dust spot.

Sensor Dust is a nuisance, but you don’t have to let it ruin your images.  Buy a bulb if you don’t have one.  Get in the habit of using it before a shoot, and when you switch the lens.  Send dust packing.

Tags: Bulb Tool, Mirror Lockup, Sensor Dust, Sensor Dust Removal