Far too much of editing time is taken up removing spots and specks from images. Once dust enters your camera it seems like only a matter of time before it comes to rest in the optical path: on the front, or worse, rear element of your lens, or worse still on the sensor; or worst of all, inside the barrel of your lens between the optical elements! The best thing you can do is prevent or minimise dust getting in in the first place, but since there are some things that are beyond the photographers’ control, this Intel will look at prevention and “cure”.
Preventing Dust Getting Into the System:
Dust and grit can enter your system from many sources, but it is most likely to be introduced by you handling the equipment, or to come off your clothes, from surfaces you sit the camera on or from a lens cap that wasn't clean.
Sure, it may just settle onto your lens or filter from the air, but it is only going to stay there if the lens is not really clean in the first place, or not dry (as might happen in humid conditions). One of the worst sources of contamination is the camera bag you rely on to protect it!
Keep your camera bag clean: empty it and use a vacuum cleaner on it every few weeks, and after shoots in sandy, dusty and windy conditions. Make sure your filters and lens caps are also clean before you put them on the lens, and be careful handling your gear- the natural oils on your skin is corrosive to the microscopic coatings on your lenses and also makes dust adhere to it.
Never leave your lenses exposed: if you change lenses, always put on the front and rear caps immediately, and work quickly; you should not leave the camera body open to dust any longer than absolutely necessary. Once dust gets in, getting it out is not easy. Point the camera down as you change lenses, so that dirt or dust is less likely to fall into the body, and to minimise the chance of anything dislodged from the lenses you are taking off or fitting dropping into it.
In windy or dusty conditions, a large plastic bag can protect your system: use it like a film changing bag - swap lenses inside the bag. In fact, if you still have a film changing bag, this is a great use for it in the digital age!
Some lens designs seem more dust-prone than others. If you are in the market for a new zoom lens, especially one with a long zoom range, remember that lenses which rotate to zoom and focus appear less prone to dust than those that push-pull, an action that seems to suck muck into the barrel.
If you do get dust on your lens, clean it off as soon as possible. This applies even more to moisture. Even fresh water contains dissolved salts which will be deposited on the surface when the water evaporates, and salt water is worse These contaminants can damage optical coatings and corrode camera fittings. Even the latest polymer cleaners will not remove them. Moistening them with clean, preferably demineralised water may dissolve them, but best to get them off before they dry.
Basic Cleaning Procedures:
Never just wipe a dry surface with a hanky or a tissue. You will turn any dust or grit on the surface into a grinder! First blow as much debris as possible away using a hand held photographer’s blower (anywhere you buy camera equipment). Blowing with your mouth is better than nothing, but remember my remarks about moisture!
Canned air, sold for blow cleaning computers and other hard to get into devices is not recommended for lenses, mirrors or sensors. The propellant can be expelled onto the surfaces and cause damage. Some shutters can also be damaged by the powerful blast of air. and if there is any airborne grit about, they can be picked up by the air stream, turning it into a mini sand-blaster.
Even after blowing, dust could settle back onto your system. A soft sable or camel hair brush should be used to get rid of any debris. If you use an artists' brush, just be careful of the metal ferrule. This is safer than wiping the surface with a cloth, and often is all that is needed. Finger prints and smudges will require a little more work.
Once the loose dust removed, you need lens cleaning liquid and a lint-free cloth. A Micro-Fibre Cloth is even better.
Never put cleaner directly onto the lens ; use it to moisten the cleaning cloth. Never use a lens cloth that has been impregnated with silica or a similar substance. These are sold to clean spectacles; the silica will ruin the coating on your lens.
Many camera, telescope and lens manufacturers now offer their own lens cleaning “pens” (Nikon, Bushnell, Kodak, Minolta, Polaroid, Fuji, Carl Zeiss). These are rebranded LensPens. The original is sold under that name at most camera shops for about $10. They have a brush in one end and a dry black carbon pad at the other. Black carbon is soft and won’t scratch the optical coating of your lens, and LensPen substantially reduces the electrostatic charge which attracts dust and causes it to adhere to lenses.
This non-abrasive cleaner can also absorb oil and fingerprints. Capping the pen not only keeps the pad clean, it replenishes the black carbon after every use. A version is also available for sensor cleaning.
Any lens cleaner will scratch a lens if there is dirt on the lens to start with. That’s why it must be blown and dusted! But cloths can also be a source of dirt and grime from just lying around or from the bottom of your gadget bag. If you use a cloth or micro-fibre keep it in a clean sealed bag. Use disposable wipes and wash your cloths frequently.
Micro-fibre and other cloths can also create a static charge on the lens surface that will attract more dust.
Wet cleaning systems leave a residual smear which can counteract the effectiveness of the sophisticated antireflection coatings on lens surface, effectively reducing the sharpness and contrast of the image.
There are now non-wipe polymer based cleaning solutions available. These were developed to clean and protect silicon wafers during the exacting manufacturing processes used to create microchips.
The polymer solution is carefully “painted” onto the lens surface and then left to dry. As it cures, it shrinks, absorbing any contamination on the lens surface into the polymer molecule. This includes particles as well as fingerprints, grease, oil and atmospheric pollution. When the cured film is peeled away, it takes all the absorbed contaminants with it. It leaves a lens surface clean right down to the molecular level!
A perfect solution? Not really: you can’t use it in the field where most of your dirt problems occur; the film is pricey (about $50 worth will clean 12 surfaces)and the process is time consuming.
The solvents used to hold the polymer in solution are acetone, ethanol and ethyl acetate. Some plastic materials are soluble in one or more of these solvents, and even though most plastic in camera lenses are impervious to the solvents, polymer can damage other plastics used in camera fittings, surfaces and lens barrels. Another problem with polymers: they are highly flammable so they can’t be taken on most flights.
On the other hand, polymer cleaners are the only really safe way to clean mirrors in SLR cameras. The polymer flows on to the surface of the mirror without dragging any contamination with it. This means that it is possible to clean the mirror without damage.
In summary: keep the lens and camera clean, protect it from dust and other contaminants, use your lens caps and keep your bag and lens cleaning cloths very clean. Use a lens pen or a silica-free cloth and always blow/brush surfaces before wiping them.
