Last week, I wrote a post about why it’s important to keep your lenses clean, and included an example photo to help illustrate my point.
Well, it turns out I was wrong about what caused those dust specks in the photo: they were NOT caused by dust on the lens, but instead resulted from dust on the camera’s sensor.
As Eric and Mike pointed out in their comments, dust on your lens will rarely show up in the end photo because you’ll always be focusing much farther than the front element of your lens (which is where the dust is). Ron Brinkmann put together an excellent article with great examples that helps show this.
For dust on your lens to be visible as specks in your photo, you’d have to be focusing your lens to an extremely close distance (even closer than what most macro lenses can do). So, any specks of dust you see in your final image most likely were caused by dust on your camera’s sensor.
How to keep your camera’s sensor clean
Now that you know where those dust specks really come from, you might be wondering how to keep your camera’s sensor clean and free of dust particles. Well, here are a few ideas:
- Use your camera’s sensor cleaning function. Most newer DSLRs these days have a built-in function that uses ultrasonic vibrations to vibrate dust off the sensor. Sometimes this function is automatic when you turn your camera on and off, but check your camera’s manual to see if it has more options.
- Change your lenses carefully. As nature photographers, we just can’t escape dust: it’s everywhere outside.. and yet we still need to change lenses, so it’s important to be very careful when doing this and minimize the amount of time your camera has no lens mounted.
- Keep the back element of your lenses dust-free. Before you put a new lens on your camera, check the back element for dust because any dust that’s there could potentially end up on your camera’s sensor (where it’s much harder to remove).
Why you should still keep your lenses/filters clean too
Although a little dust on your lenses and filters likely won’t cause any noticeable degradation to your photos, it’s still a good idea to keep them clean because with enough dust or smudges or water on your lens, you could start to lose sharpness and of course any object on the front of your lens (regardless of how small it is) will reduce light transmission.
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About the Author: Steve Berardi is a naturalist, photographer, computer scientist, and founder of PhotoNaturalist. You can usually find him hiking in the beautiful mountains and deserts of Southern California.