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The "Copperhill" Method
The D1X was our first D-SLR and in the first couple of months with it, we went through a parade of devices and techniques which purported to get rid of the "dust bunnies". If you are reading this now, you probably know that an imaging sensor is a fabulous dust magnet which needs to be cleaned regularly. These filters (anti-aliasing or low pass on a CCD, IR dichroic on a CMOS) are mounted on top of the actual sensor chip with a small gap of airspace between the two. When people refer to "sensor" cleaning or swabbing, it is these filters that will be wiped with a swab, and not the actual CCD or CMOS. Other than making your light background images look like a case of chicken pox, a moderate to severe accumulation of dust particles will cause a noticeable loss of contrast in your images. That's why keeping your sensor dust-free is so critical and necessary to D-SLR photography.
There are two kinds of dust particles you'll have to deal with: loose specks that will just move around on the sensor, and "super-stuck" particles, which have the same characteristics as dried-up bug-splat on a car windshield. There are many theories as to how they become this way (the dust specks, not the bugs), including internal condensation along with temperature and humidity changes. What has become even more of a bane to us is the already alluded to chamber lubricant.
The major D-SLR manufacturers are notorious for selling brand spanking new cameras, pre-loaded with dust. You must try to stay calm, though, because if you send it back and get a second one, the odds are overwhelming that it too will be just as dusty. OK, so let's go to the user manuals. The recommended procedures in most user's guides are actually humorous in how ineffective they are. After doing exactly what was specified, including the oh-so-elegant-and-ever-so-dainty "POOF" from a bulb blower, we could hear the dust-bunnies laughing. So we waved the white flag and sent it back to Nikon for cleaning. When it returned, it had the exact same number of dust specks as before, 28, to be precise, but they were nice enough to have rearranged all 28. Here's how one manufacturer sent a camera back after a cleaning:
 Hearing from others who had the same results with Nikon, Canon, et. al., we realized that this would get us nowhere fast, so we set out to find a good working method of self-cleaning the sensor.
With frustration mounting day by day, we ratcheted it up a couple of notches and went for more power with compressed air. This device stirred up the loose dust particles - some of the dust escaped the chamber, but MOST of it just moved around on the sensor. All of them were no match for the stuck specks. We tried several types of vacuums, including various computer-vacs and a 2.25 horsepower Shop-Vac (yes, I was a wee bit desperate at that point). They performed as poorly as the blowers. Not until later did we find out how risky it is using any of the high-powered blowers and vacuums. Anyone who promises you fantastic results from a vacuum cannot possibly own and clean a D-SLR.
Then, when we were just about to give up, we came across a method which utilized home-made or pre-made sensor swabs, along with methanol - I tried both. These particular swabs are wrapped with a special lint-free cloth and the tip is moistened with a few drops of methanol. This liquid makes the dust particles STICK to the cloth for removal; a dry cloth will only push the dust around the sensor. In addition, methanol turned out to be the greatest weapon against the dastardly "chamber-lube".
EUREKA and GADZOOKS, man!!!! we immediately knew we were onto something.
As you work your way through this tutorial, what we've already touched on will be explained and illustrated in great detail, so don't worry if this is all new to you right now. The important point to keep in mind is that your D-SLR, along with all of your lenses and accessories, are quite a sizeable investment. Sensor maintenance will require you to choose the tools and method necessary to protect the performance of your camera and the integrity of your images - it's a VERY IMPORTANT DECISION.
BUT FIRST.....
 Check how much dust you really have by shooting the sky stopped at 22, run auto-levels (optional), then view the image at actual pixels. An easier way is clicking on this thumbnail and following the directions below the image. This test is every bit as reliable as shooting the sky, and you can do it anytime of the day. Another way to check for dust is to use a tool like the SensorView. This sensor magnifier allows you to keep your test shots to a minimum and speeds the whole process up nicely.
At the end of this tutorial, we hope you will be much better able to decide which tools and method to use when you're ready to clean your sensor. |
