Today I Am A Man

Well, no, just a photographer.

A less wussy photographer.

Digital cameras capture images using a light-sensitive sensor at the point where the lens focuses the image. In compact fun cameras, it’s sealed away safely inside the camera body, so it stays clean all the time.

In a DSLR like mine, however, it can get a little dusty. That’s because I can swap the lenses on my camera, and every time I do so, a little dust can get into the area between the lens and the sensor. It still has to get past the viewfinder mirror and the shutter itself, but sooner or later dust will settle on the sensor. Since the photosites on the sensor (i.e. the pixels of the image) are less than a thousandth of an inch across, even a small dust particle can cast a shadow that shows up in the image.

(This is one area where film cameras have a huge advantage. Dust can settle on the film as easily as it can settle on the sensor, but it only leaves a shadow on the image recorded at that place on the film. Digital cameras, however, use the same sensor for every image they take, so once it gets dirty it never gets clean.)

The fix for a dirty sensor is simple: Clean the sensor. Most serious photographers do it regularly.

I never have. For one thing, I really only use one lens. Not much dust can get in if you never take the lens off. Another reason I don’t clean the sensor is that most of my images are only for publication on the web, where the resolution isn’t high enough for anyone to see the sensor is dirty. Finally, I just don’t take the kind of images that will be ruined by a few dust specs.

Then, a few weeks ago, I took some shots at a party and noticed this:

Larger ImagePhoto of Cake, With Dust Spot

My God! It’s hideous! Here, take a close-up look:

Larger ImageHideous Dust Spot

I can get rid of that in Photoshop, but it’s on every picture I take, so clearly I had to do something about. This meant I had to confront the real reason I hadn’t cleaned the sensor: I’m afraid of it.

The sensor is the most important part of the camera, and if I damage it while trying to clean it, the repair bill will be huge. In the manual for the camera, Nikon says that you should never touch the sensor with anything. If you want it cleaned, Nikon wants you to send it to their service department. I’ve never even seen the sensor.

(Nikon’s advice is crazy. Photographers who work in dirty environments, such as nature photographers, have to clean the sensor every time they use the camera. Besides, in Japan, Nikon sells a cleaning kit with an instructional video. My guess is that they’re afraid of U.S. product liability law: If they tell people how to clean the sensor, and a lot of people damage their cameras, they’re afraid they will be sued.)

Technically speaking, I wouldn’t even be cleaning the sensor. I’d be cleaning the filter that covers the sensor. That filter is supposedly made of a material that is as hard as steel.

And yet, people damage their sensor all the time while cleaning it. They grind some ultra-hard piece of microscopic dust against it, leaving a permanent scratch, or they apply too much pressure and crack it. Or maybe something goes wrong and the delicate shutter slams closed on the cleaning tool. Even just scratching the filter will require a $350 repair job.

Nevertheless, despite my trepidations, last night I finally cleaned the sensor. I plugged the camera into a power supply so the shutter wouldn’t close if the battery ran out. Then I took the lens off, revealing the inside of the mirror box. I turned the camera over and enabled Mirror Up mode in the menu.

Next, I opened up a Sensor Swab. This is a thin plastic paddle with a piece of lint-free cloth wrapped around the end. They look simple, but Photographic Solutions makes them by hand in a clean-room. The thin handle is designed to bend if you try to put too much pressure on it.

I put a couple of drops of the Eclipse cleaning fluid on the tip tip of the Sensor Swab.

Then I pressed that shutter button. Faster than I could see, the mirror snapped out of the way and the shutter locked open. In the back of the box, I could see the sensor, a shiny green rectangle surrounded by a blue area. When the light hit it right, I could even see the speck of dust that was causing the problem.

Carefully, I positioned the wet sensor swab in the blue area at the right side of the sensor. Moving slowly, I swept it to the left in one motion, being careful not to lift it off the sensor until it was in the blue zone on the other end. Then I repeated the operation in the opposite direction.

That was it. I turned the camera off and the mirror closed. I put the lens back on to seal the camera up again.

I haven’t actually tested it—by taking a picture of something smooth like the sky and looking for spots—but I think it went okay. I’m feeling virtuous.