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.
I’d like to thank Eric Pohl and Michael Smith for kindly correcting my error (see their comments on the original post). And, please accept my sincere apology for being wrong about this!
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.
Interesting article. The last pictures I took in a pasture of horses had a lot of white specks on them. I assumed this was dust or pollen on the lens but now I know to look deeper. I’m going to check my user manual and see if there is an automatic sensor cleaner on my Canon. If there isn’t, what can be done about dust already on the sensor?
Chuck De Luck says
I sacrificed my camera to the Playa at Burning Man )( 2009 and it survived 10 days of dust. ( Big time dust)
The outside of the 20d took a beating, but I chose one lens before I got there and never took it off and had no problem with dust on the sensor.
A couple cans of compressed air to dust the lens and body every now and then and the camera is fine.
The LCD got trashed, but who uses that anyway?
Back from the Burn…. http://arppworks.blogspot.com/2009/09/back-from-burn.html
Chuck De Luck
Steve, good for you on correcting your original posting. And good tip to keep the back element of the lens extra clean.
Chuck De Luck says
Make that a SECOND year at Burning Man)( with the same camera and same lens.
The only thing I learned in a year is,
Make sure your sensor is “clean” BEFORE you get into a situation where you can’t clean it. lol Photoshop took care of the spots, but coulda saved a Lot of work with being prepared forehand.
Changing a lens is the crucial time for dust invasions.
Compressed air to clean before changing lens, and like Steve said, pay attention to the back of the lens and around the junction of the camera / lens.
I blow across the back element and never straight on, driving the dust into the lens.
One note about compressed air, Always keep the can vertical, or liquid will spray out and that will toast a lens.
My LCD is still trashed on my 20d, but aside from accessing the menu, I don’t use it.
PS, Your camera manual is your good friend, keep it with you and read the darn thing.
Pete Belardino says
Good article Steve ! I would also say not to listen to camera manufacturers or camera shops ! I was quoted $45.00 to clean the sensor on my Canon ! Bought a kit on Amazon for $18.95, had it cleaned in 5 minutes, and have enough product left for one or two more cleanings ! It’s not a tough job….you just need your camera manual to lock up the mirror !
Also, when changing lenses in the field, point the camera straight down to minimize dust and dirt blowing onto the sensor !