We’ve all had to deal with it, dust spots in images. The more stopped down the lens is and uniform the scene is in texture the more of a problem it is. The way I see it, dealing with dust is a three-part process. Cleaning the camera and sensor, minimizing the dust that can get into your gear, and finally, dealing with the dust spots that do show up in post processing.
Cleaning your Gear
This is a bit of a both sides of the equation thing, some of it is related to dust and some of it is related to maintaining the optimal functionality of your gear. I clean my gear every time I get back from the field. If you don’t currently clean your gear and want to know how, Moose Peterson has a very solid 4-part video guide at the top of his video archive page. It’s well worth the watch.
That said, there are a couple of things I want to call out as being important and a couple of additions I’d like to make.
Using a Cotton Swab to Clean the Mirror Box
Moose suggests using a Q-tip to remove fine metal shavings and dirt from the lens mount and mirror box. I had never thought of doing this, and I really like the idea. However I’m not sure if a cotton-swab is the best solution, though I don’t know anything better. I’ve found that it’s not hard to get fibers snagged on something and pulled from the cotton. Fibers, that in turn have to be cleaned out carefully with tweezers one at a time.
Also, keep in mind that many digital bodies now have tacky pads in the mirror box to catch and retain dust and you don’t want to go rolling a q-tip though one of those-though you shouldn’t be putting a q-tip that far into the mirror box.
Clean the Body and Lens Caps
I wash my body and sometimes lens caps—yes, with soap and water—depending on how dusty they are. Since Canon doesn’t make, to my knowledge anyway, metal body caps at all and the plastic ones will collect dust in hard to reach crevices it’s the easiest way to get the dust out of them. Just make sure they dry thoroughly before putting them back on the camera.
Also, don’t forget to clean the lens mount on the lens. A little rubbing alcohol on a cotton swap here will turn up all kinds of crud that can get into the mirror box eventually.
Wipe down Your Gear When You’re Done
Not sensor dust related but I just wanted to re-emphasize the importance of this especially when shooting in hostile environments. And just an added note, when I get back from somewhere like the beach I will clean the front filters with lens cleaner to insure there isn’t any salt residue left on the glass even if they appear clean.
This is doubly important when shooting in environments that are aggressive to camera gear and the coatings used on lenses. The sooner you do this the better as well.
While you’re cleaning your gear in general, don’t forget everything else, especially if you have a good quality tripod. In a harsh wet environment, aluminum tripod legs (and the aluminum in Gitzo leg locks) can corrode and seize, freezing the legs in whatever position they were left.
Cleaning Your Sensor
If there isn’t a way to start a debate, this is probably it. Yes, cameras are precise instruments and the last thing you want to do is damage the sensor, god only know how much you’d end up paying to have that repaired.
The official line is that it’s safe to blow the sensor clean with something like a Rocket Blower, if that doesn’t remove the dust you’re supposed to send the camera to the manufacturer and have them clean the sensor. In practice, the camera isn’t nearly as fragile as it sounds and there are several approaches to cleaning the sensor.
There are 3 major methods, blowing, brushing, and wiping, loosely named based on how they work.
Blowing away the Dust
Blowing is the simplest, safest and often least effective. You will need a proper blower, canned “air” dusters can and likely will leave a residue on your sensor that will require a more thorough cleaning to remove. I use a medium Rocket Blower, the small works well enough if you need to pack it in your bag for the road. Visible Dust, the makers of the Arctic Butterfly, makes a “Zeeion blower(Affiliate Link) ” that they claim is even better because it statically charges the air and filters it before it blows it in your camera.
Blowing will only remove dry loose dust particles, not sticky or oily ones. The unfortunate, reality of modern self-cleaning sensors though, is that the camera can already deal with this kind of dust quite well on its own, and overall blowing your sensor clean isn’t going to do much. However, it’s still a good idea to blow the sensor clean before you go into one of the more aggressive steps, there’s just no sense having any more dust there than necessary.
Brushing away the Dust
The second method of dealing with dust is brushing. This typically involves using a soft brush of sort, gently dragged across the sensor’s surface, to lift away the dust particles. The most well-known of the sensor cleaning brushes is the Arctic Butterfly(Affiliate Link) by Visible Dust. There are also some “riskier” DiY solutions that use thoroughly cleaned artists’ paintbrushes or makeup brushes.
Brushing is the second most aggressive cleaning method, it can deal with sticky dust that blowing can’t, but cannot deal with oily residues. Like wiping, there is a level of risk in putting anything inside the mirror box and touching the sensor.
Wiping away the Dust
Better known as wet cleaning, this is the most aggressive and best cleaning solution. It will deal with all forms of dust, as well as any oily residues on the sensor’s surface. It’s also arguable the most controversial and most commercialized. There is a huge verity of products available for this, from reusable systems that you have to assemble at cleaning time to disposable one use pre-wetted pads.
I use a system from copper hill images; it uses readily available Pec*Pads and Eclypse E2 cleaning solution with a custom “spatula.” In the intervening years Photographic Solutions, the makers of Pec*Pads, have introduced their own disposable sensor cleaning solutions(Affiliate Link) , though they are less hassle to setup, they tend to be somewhat more expensive on a per use basis.
General Sensor Cleaning Tips
Regardless of cleaning method and especially with the brush and wet methods where a physical instrument must be placed inside the mirror box, having stable camera power is of the up most importance. I strongly recommend using a fully charged battery (or multiple if you have a battery grip), instead of an AC power adapter, to insure that there is no power interruptions while you’re cleaning.
It’s also a good idea to work in a dust free area. Right, dust free, who am I kidding.
Actually, there are a few ways you can deal with dust in the air. One is to clean your camera in the bathroom after running the shower on hot for a few minutes and letting the room cool a bit. The condensing humidity will trap the dust in the air, at least temporarily. Barring that, if you have a fan in your room; turn it off and let the air settle before you start cleaning your gear.
In either case, it’s also useful to work quickly and keep the camera’s mirror box covered as much as possible.
For example, my cleaning procedure works much like this. I start by putting the camera in manual cleaning mode, then holding it lens mount down, and blowing out the mirror box. I then turn the camera off, and put the body cap on it before returning it to my desk while I assemble the swab. Once the swab is assembled, I put a few drops of eclipse on the swab and I’ll again put the camera in cleaning mode, then place it lens mount up on my desk. By the time I have the camera in cleaning mode, the swab is just moist enough to be ready, so I can pull the body cap off and clean the sensor. When I’m done cleaning the sensor, I immediately reattach the body cap, then go about turning off the cleaning mode.
Minimizing Points of Entry
Use whether sealed lenses and don’t change them in dusty locations, barring that change lenses sparingly and quickly and while shielding the camera from the wind.
Minimize the number of ways foreign particles can enter the camera body when you’re in the field. Not all sensor dust is due to material from inside the camera migrating to the sensor, there is still an environmental component that’s more of an issue in some environments than in others. Places like beaches or sandy areas are a good example; a little wind and there’s a lot of very fine particulate matter flying around almost constantly, couple that with the salt spray in air that tends to leave a residue on everything exposed to it, and you have a recipe for a dirty sensor.
The best way deal with these environments is by using weather-sealed lenses and not changing them at all in that environment.
Barring that, the next best thing is to keep the number of lens changes down to as few times as possible and as quickly as possible.
When all else fails and you have to change lenses in windy sandy adverse environments, try to form a shield against the wind by standing with your back to the wind. Then work quickly and close to your body and try to shield your gear with your hands and body as much as possible instead of out at arm’s length on your tripod or something. This is also a place where being able to change lenses with practiced ease is a good skill to have.
Dealing with Dust in Post
Dealing with dust in post shouldn’t be hard, it’s most readily visible in uniformly colored areas, and that makes it easy to clone out. In fact it’s very easy if you use the manufactures’ software (like Canon’s Digital Photo Professional or Nikon’s Capture NX) there is often a way to capture a dust deletion image in the field while you’re shooting and have the software apply it automatically when you process the image.
Using 3rd party image editors makes things a little more complicated, but many of them make the process streamlined enough that it still can be quite fast.
Tricks for Dealing with Dust in Lightroom
I use Adobe’s Photoshop Lightroom, and I’ve found a few handy tricks to dealing with dust.
Use Home and Page Down to Scan the Image
The first trick is to insure you cover the image at 100% magnification without missing any spots. Lightroom provides a simple mechanism to do this. In develop after you’ve zoomed into 100% magnification, press the “Home” key to move the view to the top-left corner. From here you can press the “page-down” key and the view will advance down the image to the bottom. When you reach the bottom of the image, pressing “page-down” again, will shift the view to the top and far enough right to align with the first pass you just made. By repeatedly pressing “page-down”, you can cover an entire image from top-left, to bottom-right without missing any of the image.
Sync Dust removal between Images
Dust spots are static, so they won’t move between images. Which means, that you can de-spot one image, and sync those fixes to neighboring images using Lightroom’s ability to sync development settings. This makes it much easier to deal with spots in a number of similar images where you can be sure the background won’t change drastically.
Edit and Process only the Necessary Images
This should be somewhat obvious, but instead of trying to remove dust spots from all your images, edit down your images to the ones you really want before you start processing them. With fewer images, you can spend more time cleaning them or verifying that dust really is a problem.
You can jump directly to the spot removal tool in Lightroom by pressing the ‘Q’ key on the keyboard while in any library module or in develop.
Dust will likely always be a problem with digital photography and dealing with it isn’t just about cloning out spots in post-production. Keeping your camera clean and well maintained, especially the lens mount and mirror box, means you have somewhat less to worry about, but you’re not out of the woods.