Article by Jean-François Landry
Yes, there will come a day when a treacherous finger will leave its greasy print on the front glass of your lens. And, yes, despite all the precautions you take when changing lenses, a speck of dust will eventually succeed in breaking through your defences and establishing residency on your sensor. When these moments come, you’ll need to clean your equipment. And the task might make you feel like Hercules at the Augean Stables.
DUST, SAND AND HAIR ON OPTICS
As much as possible, avoid touching the surface of the glass when cleaning your lenses. A basic air blower works really well. But use a good-sized, high-quality air blower; a scrawny, cheap air blower is only good for useless puffs of air. You need remove the dust, not tousle its hair. Your blower should be at least as big as a pear. Avoid cans of compressed air because they can spit out a stream of frozen water that can damage the glass or the coating on the glass (by cooling the surface almost instantaneously). And no matter what, don’t blow on the glass! (Your saliva would cause more damage to your images than the dust!)
If a speck of dust is particularly stubborn, use a small make-up brush with soft bristles to dislodge it before expelling it with air from the air blower. Check out the L’Oréal Paris Kabuki brush ($20) or another similarly soft brush.
Cleaning the surface with a clean cloth is not enough; you’ll just spread out the fatty matter like icing on a cake! You must use an alcohol-based liquid in order to dilute the oily mark.
FINGERPRINTS ON THE LENS
Start by identifying and scolding the culprit. The miscreant will be easy to find; you have a fingerprint! These pesky marks are deposits of grease and oil from the body. Cleaning the surface with a clean cloth is not enough; you’ll just spread out the fatty matter like icing on a cake! You must use an alcohol-based liquid in order to dilute the oily mark. There are a slew of cleaning products on the market, but isopropyl alcohol (also called isopropyl rubbing alcohol 70% USP) does the job well.
The idea is simple: never clean “dry on dry.” Doing this scratches the surface. To apply the cleaner, use disposable optic cleaning tissue or a reusable microfibre fabric cloth made especially for cleaning optical surfaces. Begin by covering the tissue or cloth with alcohol and rubbing it over the surface of the optic. Then, with a second paper or a dry part of the cloth, use a circular motion, starting in the middle and moving outward, to eliminate all traces of the odious print. (Note: microfiber cloths are washable! Eventually, though, they become saturated in fat and useless. Personally, I wash them with a little liquid dish soap, rinse them thoroughly and then hang them to dry. Running them through the washer and dryer will work too, but avoid using fabric softener because it’ll make the fabric less absorbent.)
Now to address lens- cleaning pens: these objects have a felt-like surface soaked in a secret substance (that strangely resembles graphite and oil) that you sweep all over the surface of the glass. Even if it seems like a really good idea and even if the results look okay, restrain yourself. If you are unlucky enough to land on a small speck of sand while cleaning, you will irrevocably scratch the surface of the glass. In addition, some of the oily cleaning mixture will remain on the surface. In backlit photos, your image will lose a little contrast and definition, and you’ll be left wondering why. (Yes, I have a grudge against tools like these that seem like good idea but actually aren’t.)
DUST ON THE MIRROR
Particles on the mirror aren’t a big deal since the mirror lifts to let the light in when you take
a photograph. If, however, they frustrate you and keep you awake at night, don’t use the air blower to get rid of them because that can send them deeper into your camera and cause them to land on the sensor instead! And there, they will really be irritating. Instead, use a cotton swab lightly soaked in rubbing alcohol to remove them delicately, without applying any pressure.
DUST ON THE GROUND GLASS
Never, ever touch the ground glass. It is made from very fragile plastic; you only have to look
at it a little too hard for it to scratch! Small specks on it won’t appear on your images, since they’re outside the optical axis once the shutter is released. But if they interfere with your artistic temperament, have this taken care of by a talented camera repair technician whose skills you trust completely.
Never, ever touch the ground glass. It is made from very fragile plastic; you only have to look at it a little too hard for it to scratch!
DUST ON THE SENSOR
Oh no, not the archenemy! In facing this formidable foe, the most important thing to understand is that the surface of the sensor is very fragile and easy to scratch, so you should avoid all contact if at all possible. If that’s not possible, you have a few potential strategies.
THE DRY METHOD
Here, once again, the air blower is your best ally. Some squeezes on the air blower should get rid of particles, and there are loupes specifically made for this that will help you evaluate your success. Are you facing a particularly stubborn speck of dust? Use a soft brush to oust the intruder.
If these approaches don’t work, however, you’ll have to use more drastic measures to rid yourself of your nemesis.
THE WET APPROACH
As a last resort, you can use a specialized tool to directly touch the sensor. This route has its fair share of risks, so be exceedingly careful. The tool is a wand with a cloth pad on it, and it’s about the size of the sensor. Begin by moderately wetting the pad with a liquid made for the task. It will help dilute the oils and lower the risk of scratching. Place the wand to the left of the sensor, perfectly flat. In a uniform movement, while applying even pressure, like what you would use to stroke a baby bird, move the swab to the right side, along the width of the sensor. That’s all. One swipe. Verify the quality of your work, and if you see imperfections, residue or marks, turn the swab over and do a second swipe, in the same manner as the first.
Sooner or later, dust, hair, particles, fingerprints, splashes, or all sorts of dirty things will make an appearance on your equipment. Always keep on hand what you need to vanquish them.