A lot of people have asked about cleaning lenses and dust in the optics. I’ve considered doing a few short videos on glass cleaning techniques and tips but never really went through with it. It’s difficult to explain, it’s a skill that comes with years of practice. It’s like asking a surgeon how to perform surgery… He can explain and even demonstrate, but that doesn’t mean you should attempt it yourself. Thus, I always say the best way to clean your lenses is to not let them get dirty. I do a lot of work with still photo lenses these days with the whole DSLR revolution and all and every now and then I get a request to clean some dust, dirt, or debris from inside an otherwise pristine Canon or Nikon lens or similar. I almost always have to turn people down simply because the cost of labor compared to the cost of the lens is prohibitive. Your average Canon Eos lens costs a few hundred bucks. The average time to disassemble a lens enough to access debris inside the optics, clean in out (properly), re-lubricate, reassemble, align and collimate optics, is about 4-6 hours if not more. This amount of time in service can equal or exceed the value of the lens, in which case it’s usually better just to buy a new lens. Some people like to think that the “Pro” lenses with their weather sealing are immune to dust and contamination but that’s simply not true. They are better at keeping contamination out, but not perfect. Some of the higher end L glass would be worth a good cleaning if it’s a specific lens you are partial to. The cost:value ratio prohibition doesn’t usually apply with cinema lenses. Even professional cinema lenses get dust in them on a regular basis, but these lenses are designed to be serviced and cleaned. If you shoot in a clean studio environment and keep your lenses in well sealed cases when they aren’t in use, you probably won’t see much dust in them over their life. If you’re a run-and-gun shooter, swapping lenses constantly in the desert, you’re going to have problems with dust and debris sooner or later. I have a client that shoots motocross events for a living with his Epic camera and a couple of Angenieux zooms. His lenses get destroyed on a regular basis, coming back from jobs covered in dust, dirt, mud, everything that doesn’t belong in a lens. The lenses are worth quite a bit which makes cleaning them worthwhile for him. We clean them up, calibrate them, and send them back into the field to shoot again.
Some shooting situations are more prone to dust and dirt contamination than others, but you can always take precautions. Use rain bags in dusty environments to keep as much contamination out of the lens as possible. Make sure your lenses have a nice, clean home to live in when they aren’t in use. If a lens needs to be swapped during a shoot, bring it’s case over to the rig and swap it right there so that it doesn’t get left out. Clean your cases on a regular basis by blasting them with pressurized air. Canned air will get the job done, but try to use something with a little more uumph to it. A clean case makes for a clean lens. Lens caps are actually more important than you think. Not only do the protect the front and rear element from scratches, but they can also keep dust out of areas it shouldn’t be. When you remove your lens cap, if it’s a small one, try not to put the cap in your pocket. It just sits there and gathers pocket lint and dust, then gets transferred to the lens once you put it back on. This is especially true for still lens caps with their cool little springy plastic clamps. They’re dust magnets with all their nooks and crannies. Try to use the simplest cap you can find so you can see when there is dust that could contaminate. Dust inside a lens always starts on the outside, so if you keep the outside clean, you reduce the risk of contaminating the inside. Another good thing to keep around is a wide painters brush. Just a plain, synthetic 3″ brush. They work great for dusting of the exterior of lenses (and all gear for that matter) and only cost a couple of bucks. Give your lenses barrels a good brush down on a regular basis. Don’t use this on the glass as it can easily scratch the surface with picked-up particles. Keeping the glass clean is equally important, but more demanding. Touching the glass with anything, wipes, spray, tissues, cloth, etc., should always be a last resort. Clean as much as you can with pressurized air. The squeezey-rocket-blowie-thingies are cool, but they really aren’t powerful enough to dislodge particles stuck in the perimeter of the lens. Use canned air. A lot of folks will tell you that the propellent will hurt the glass which is true if you hold the can upside down and spray it like Mr. Freeze… Spray a few quick bursts away from the lens to make sure there isn’t any liquid in the nozzle and proceed to clean away with your clean compressed air. Sure it’s a lot more expensive to buy can after can, but it’s far more effective than a little rubber rocket. Should you need to take it a step further and clean some glass, try to bring it to a professional. I realize this isn’t convenient for most people, but the most common way to get micro scratches on a lens is from improper user cleaning. There is no magic product that keeps lenses clean. Just use a little bit of common sense and good old fashioned care and attention to detail and your lenses should stay cleaner, longer.