I once knew a man who refused to dust his negatives before he printed them in his darkroom; he said he was happiest when dust spotting, so he took what came in terms of dust on his prints and happily spent hours filling in dust spots with dye and brush, fixing problems that could have been prevented in seconds.
Dust is still a problem in the digital age, and unless you’re like this man, and you want to spend your time doing monotonous, repetitive work, you can save a lot of time by minimizing dust at each step of your workflow, freeing time for creative work. Here are some recommended best practices to make sure your valuable time is saved for creating, not repairing nor replacing.
Dust comes into our cameras through opening camera bodies when we’re changing lenses. It can also come into the camera through the lens. Certain lens designs, as they zoom in and out can suck dust onto the sensor. This seems to be more of a problem with older, push-pull zoom designs than the circular designs prevalent now.
What to do? If you know you own a lens that seems to create more dust problems when using it than other lenses you own, this lens needs to be replaced. Failing that (we can’t all go out and buy lenses at a hat’s drop), the best thing for every one to do is to be very serious about keeping dust from entering your camera body OR your lenses. Starting from the outside of your camera, here are some dust control tips.
Best Practice #1 – Manage external dust to keep it from becoming internal dust
A damp cloth used to wipe down the interior of your camera bag is a good idea; done regularly, this will keep dust in the camera bag to a minimum. If you regularly work in dusty environments (as when shooting cattle roundups, something I’ve done for many years) everything that can be put in ziplock baggies should be put there, and only pulled out when needed. In such cases, taking a vacuum cleaner to your bag when returning from a dusty shoot is excellent practice.
A second valuable tool is a lens dust brush. Various companies make these, some with squeeze bulbs to use air while dusting with the brush, others just a simple brush, with the elements touching lens elements carefully selected to prevent scratching. I keep mine in a zipped plastic bag to keep it squeaky clean.
As with other parts of your gear, the old truism that “it’s better to keep your lenses clean than to keep cleaning your lenses” is very much alive in the digital age, and applies to sensors even more than lenses. Dust on the camera body or in the camera bag soon migrates to the interior of the camera, to the sensor or the rear lens elements, so exterior dust control is a critical part of interior dust control.
Best practice #2 – Check your sensor for dust often; it’s quick and easy
Turning to the interior of your camera, how do you know if you have dust on your sensor? An easy check is to take your camera outside and point up at a clear sky (nothing except sky, when possible), or a white wall. Use f/11 or f/16 as your lens aperture, and shoot pictures focused at infinity. Any dust will show up on your screen when you put the images into your computer; for checking exactly, zoom to 300% or larger, and examine the computer display to be sure minuscule spots of dust aren’t present. If they are, circle the offending spot(s) on the file with a brush tool in a bright contrasting color, so you can know where to concentrate your blower brush on the areas where the spots are.
If your precautionary steps aren’t enough, and you end up with dust from your camera and/or lenses on your sensor, take heart; all is not lost. Here are best practices for minimizing the impact of dust on you and your images.
Best Practice #3 – Use your camera’s automatic dust removal
Many contemporary cameras have an auto dust removal tool you can turn on to help minimize or eliminate dust on your camera’s sensor. These can be configured in various ways; mine is set to automatically run as soon as I turn on my camera, and to run again whenever I turn my camera off. Some cameras only offer options to clean the sensor on command. Whatever options you have and select, your goal should be to make sure that the anti-dust routine is run regularly. If you can, set the camera to do this automatically and forget about it, at least until your regular checks of your sensor show a problem with dust. When you see a problem, you can trigger the auto-sensor shaking dust removal routine and test again. Often that’s enough, but what if it isn’t?
Best Practice #4 – Use a Firefly or a dust blower
When dust doesn’t drop off using the automatic sensor cleaner, or you don’t have an auto clean routine on your camera body, you’ll need to step up your cleaning game. Usually the next step is to use a blower to push a stream of air at the sensor in your camera. A word of warning, please: the long tips of most squeeze bulb blowers are waaaayyyyy too long, and if not used very carefully, will penetrate too deeply into your camera body and scratch your sensor. Be very careful doing this operation.
Start by putting your camera face up on a table, with strong light. Be sure you have lots of light shining up into the body so you can judge the depth to which the squeeze bulb blower tip should penetrate, and no deeper. Figure out this depth, and use a permanent marker to draw an obvious line around the tube in a contrasting color, heavy enough to see.
Now, put the camera body on a tripod, and rotate the body so the opening is facing down. This lets dislodged dust fall straight out of the body to the floor, as well as ensuring you don’t move the camera body by accident in such a way that you scratch the sensor with the blower tip. Lock up the mirror for cleaning (consult your manual for instructions), and then insert the tip of the blower brush into the opening, being extremely careful not to go past the mark you drew previously on the blower nozzle.
Make sure you have enough light to see up into the camera body opening from below. Only then should you gently insert the squeeze bulb into the opening and start squeezing air vigorously onto the sensor to dislodge dust. As noted above, referring to the spots circled in red is helpful in concentrating the air stream where most needed. Squeeze vigorously to dislodge dust, and do this several times, amount varying based on the vigor of the squeezes and the amount of dust you found on the sensor.
Put a lens back on the camera, and shoot the sky again to see if you got all the dust. If you didn’t, repeat the operation, noting carefully where the dust is located, and try again. Sometimes it takes several repetitions to get all the dust.
When I do this process, I use a Firefly, shown above. This device has three great features that work together; a very short tip, almost eliminating any risk of scratching the sensor, a good sized squeeze bulb to generate lots of air, and, best of all, a device that inserts a stream of charged ions into the air being forced onto the sensor. The charged ions help the dust de-bond from the sensor surface and fall out. I can’t recommend this device enough; it’s a great tool for keeping not only your sensor but your lens surfaces clear of dust. I particularly like it for deeply recessed rear elements of lenses, where dust is hard to reach and harder to remove. Regrettably, the company website is currently inactive, so you may need to watch for one on eBay to grab your own. Not inexpensive, but worth every penny.
Depending on how heavy the dust is, you may need to do this blower-brush cleaning more than once. A couple times, I’ve had to do it three or four times, but eventually, most stubborn dust falls out and goes away.
What if it doesn’t?
Best Practice #5 – Clean the sensor of sticky dust
When dust on your sensor is not removed by auto-shake or by an air bulb or Firefly, even stronger measures are called for. What remains is either sticky dust (nifty technical term, no?) or an oily mess. You can opt to take your camera or send it in for a professional cleaning, which is a good idea. What to do if this option is not available? If you see stubborn dust spots on your screen, as opposed to irregular smears (which signal oil or other sticky deposits), a new device getting some good buzz is the Sensor Gel Stick. This product lets you put the gel stick directly on the dust spots (referring to your red-circled spots on your test image), press gently but firmly, and lift the spots off as they cling to the gel stick instead of your sensor. Nifty, eh? Then, you remove the dust from the Gel Stick and you can use it again. Noted commercial photographer William Faulkner says, “Gel sticks are really great. The one thing about the gel method is that, so far, I’ve never “added” a problem by using one.”
An alternative, also useful for smears of oil or other sticky stuff that other techniques won’t remove, is to use liquid sensor cleaner and sensor swabs. I have used this set of products for years, both the set I keep at home (dry swabs and a bottle of liquid) and pre-moistened swabs for use on the road. (I carried the bottle and dry swabs on a couple trips; NOT a good idea.) The full product line can be found on PhotoSol.
You can find the pre-moistened swabs on Amazon (Note that the swabs come in different sizes, so be sure to buy the one that matches your sensor. You can check your camera model against swab sizes here).
These swabs must be used carefully. You’ll be tempted to take more than one swipe across the sensor with each swab; DON’T! It’s much less expensive to use a second swab for any remaining dust than it is to replace a sensor because you dragged a previously-caught piece of dust down the sensor with your already-used swab. Don’t cheap out; one swipe from edge to edge, and away with it, into the flames.
If you’ve gotten a particularly big oily mess on your sensor, I recommend you send it for a pro cleaning ASAP. Don’t fuss with trying to clean it yourself unless you absolutely have to do so because you must use it right away.
Best Practice #6 – Be aware of and address dust when shooting in dusty environments
Shooting in the real world often involves working in dust. Whether in an old, poorly cleaned church and hall for a wedding and reception, the afore-mentioned cattle roundup, an outdoor wedding or sports event in a strong wind—examples are endless, and all provide opportunities to come back from the assignment with much more dust in your camera and on your sensor than when you left home.
When shooting in dusty places, I use rubber bands and giant bags to cover all the camera except the lens front, and the front of the lens has a UV filter on it to protect the front element. I keep a “Dust Kit” bag in my camera bag , as shown.
Best Practice #7 – Keep all work areas, especially printing and drying areas, as dust free as possible
Where I live, dust is a constant factor.
Freshly plowed fields, within the city limits join with afternoon breezes to guarantee a freshly washed car soon looks dusty, and freshly cleaned lenses often are dusty right away. Whenever possible, I recommend using dust-removing air cleaning devices. Clean the filters in these devices often, as well as built-in heating and cooling air ducts, filters and other areas.
This is important for your whole studio/office/home, but particularly your shooting and printing areas. Adding a portable air filtration device (ionizing models) and a humidity controller in the shooting and printing areas will add extra help in controlling dust, with a side benefit of helping you to control color more precisely when you control the humidity in your printing environment. Many a believer in this aggressive approach to dust control has been made after the first time a 24×36 inch print is marred by dust that has drifted onto the paper as it’s being printed, ruining the print. It only takes a few wasted big prints to make a convert!
Best Practice #8 — Be careful when using canned air
Photographers are often tempted by those discounted multipacks of canned air sold at Costco and other big box stores. If you have bought these, proceed with caution. Why would I say this?
Strong jets of compressed air are so strong they often blow dust into other places, usually undesirable. If you were to use them inside your camera, odds are good you’ll knock dust into another part of the camera, where it may fall back onto your mirror or sensor (or both). A blower brush or Firefly is a great provider of enough air to dislodge dust from a sensor without pushing it into other parts of the camera. Proceed with great caution if you use this tool.
Another concern when using these cans of compressed air is possible damage from cold. NEVER shake the cans when using them. You can feel how cold the can is when using it, especially after shaking it, and it’s possible to crack a mirror or lens element if you shoot a jet of cold, compressed air at a fragile crystalline object, especially when you use the little plastic straw to narrow the stream of air.
Finally, a common effect of dusting elements with canned compressed air is leaving a residue behind. The goal is to clean the surface of dust, not remove the dust and leave goop behind, necessitating more cleaning.
This brings us to the end of this blog post. Here’s to masterful dust control for all of us.
Kevin O’Connor helps design and test software, is a graphic designer and photographer for multiple clients and companies, and fixes people’s (and companies’) color.
He has consulted to multiple companies, including Apple, Sony, Fujifilm USA, and X-Rite. He loves teaching good color practices to enthusiastic learners.
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