Photography Notebook:
Digital Photography's Dirty Little Secret
You won't find it discussed in polite company. Everyone seems fine not talking about it and seems to pretend it doesn't happen. But I knew it was happening to me, and I was afraid to ask anyone about it.
One day, it got so bad, I sought professional help. That fixed it temporarily. I thought I was fine. I could handle it. It would never happen again, I thought. But then it did happen again. So one night, alone, I surfed the Web to get some help.
The Sensor Attracts Dust
A digital camera's sensor attracts dust. Much of this dust doesn't show up on photos because it is so small. When the f number of your photo is low, this dust also doesn't come into focus. But sometimes, a spot or two or more shows up on your photos, repeatedly in the same spot:
Note the spot that appears in the horizontal image in the lower left quadrant, just in the tallest buildings reflection in the water. It shows up again in the vertical orientation in the sky just left of center in the upper left quadrant. This spot was on the sensor. When I first found it, I didn't have any knowledge of sensor cleaning, so I was very scared and confused. What I did was find a local camera shop (actually in the next county!) that did in-store cleaning of the sensor for about $20. I was pleased with the result, but then I decided to spend some time learning about sensor cleaning options.
The main thing is that your camera's warranty might be invalidated if you touch the sensor (actually the sensor covering) in any way. Use due caution in what you choose to do for sensor cleaning, and be aware of your camera's warranty and instructions.
Sensor Cleaning Options
I now have a variety of approaches to cleaning the sensor, and I employ them in order of least intrusive to more advanced.
Automatic Sensor Cleaning
First, I leave the automatic sensor cleaning option on in my Rebel camera. I have no idea how effective this is--I'd like to find research results some day--but I feel this automatic sensor cleaning is at least a first line of defense.On the Rebel camera, go to Menu->Options (2) and Sensor cleaning. Then set the Auto cleaning to Enable. This sets to sensor cleaning to activate whenever you turn on or off your camera.
Seeking Professional Help
If you are concerned about cleaning the sensor yourself, you might find a professional service to clean it for you. These can be pricey, and when I was trying to find one, some required sending the camera away with additional shipping costs. I did find one camera shop that did in-store cleaning for a reasonable cost.
Accessing the Sensor
The next methods of cleaning I use involve accessing the sensor. Be careful in accessing your sensor. Understand your camera's warranty. Start with a battery that has been recharged fully to avoid a battery running out of power when you are accessing the sensor and then slamming the shutter opening shut.
On the Rebel camera, go to Menu->Options (2) and Manual cleaning. Then click ok. You'll hear a click, and you can remove the lens (put on its end cover), and then look inside your camera at the sensor.
The next techniques involve accessing the sensor.
Seeing Dust
In order to clean dust, you have to see if it is on the sensor in the first place and also to check if your cleaning method worked. There are different ways to check the sensor for dust. One involves taking several photos of the blue sky (or a pure color sheet) on a high f number setting such as f22. You then download the image from the camera and examine it on a computer screen using image viewing software to zoom in and look for splotches that may appear in the same position at different focal lengths (to eliminate the possibility that the splotch is on the lens). This procedure works, and I've used this method several times, but I find it very tedious and time-consuming.The best way I've found is direct inspection of the sensor itself. After looking at a variety of ways to view the sensor, I chose the BriteVue sensor loupe. This device has lights that illuminate the sensor and a magnifying lens that allows you to view the sensor surface. I find this device to be excellent, and a huge savings in time.
This loupe works quite simply. You turn on its LED lights, rest the loupe on your camera's opening above the sensor, and then you can adjust your eye position to where you can see the entire sensor clearly. You will see the dust specks, if any. I find it quite amazing how well this device shows the dust. I wouldn't be without it, because it makes it possible for me to try a sensor cleaning method and then immediately see if it worked.
This loupe is expensive, but its cost is roughly that of
several professional cleanings
(plus those cleanings involve
the time and expense of traveling to the camera shop). With this device,
you can check immediately and without having to take a photo.
Blown Air
The next level of cleaning I try is blown air. I find it essential to have a bulb to do this. In many places that I looked, they recommended the Giotto rocket blaster. It looks similar in shape to a rocket. There are other brands on the market, and they indeed might work fine, but I got this large air blaster, and I have never regretted it.
To use the air blaster, squeeze it a few times away from the sensor so as to blow out any dust or debris inside it or near its tip. Then, while keeping the tip of the blaster just above the camera opening to the sensor (don't let the tip go in there and touch the sensor!) push the bulb quickly and firmly. A blast of air will be pushed onto the sensor surface. You can then use the sensor loupe to examine your sensor to see if this was effective.
If you can use forced air to clean the sensor, stop. You've not touched
your sensor with anything except air, and you can then go about your
photography.
However, you may find that blown air just doesn't get the dust off the
sensor. In such case, you can try some other methods.
Sensor Brush
The next level of cleaning that I use is a sensor brush. I did some research, and I had been so pleased with the sensor loupe from Visible Dust, I looked at their Arctic Butterfly Brite Sensor Brush. What this brush does is allow you to gently swab your sensor with bristles that have been spun to remove dust on them and charge them electromagnetically. The brush does this with a motor to spin the shaft of the bursh. With the motor off, you gently swab your sensor with the (non-spinning!) bristles. Used in conjunction with the sensor loupe, you can swab particular sections of your sensor and examine to see if the dust is gone.
In practice, I found this brush to be effective, and I am glad
to have it. However, I think the brush
is a bit expensive for what it does. I would
say that if you are on a budget,
delay buying this sensor brush until after
getting and learning the "swab" method of cleaning, covered in the next
section. But once you
master the swab method, and can
afford to
obtain this brush, you can then use it as a step
before resorting to the swab method.
Swab Method
I carefully examined many accounts of sensor cleaning, and the repeated warning was that once you decide you are going to touch your sensor with a swab to clean it, you have to be careful. That is true--be careful, but don't be terrified. I have found this swab method to be effective. In fact, I feel confident now using it--with due caution at all times--before I would seek professional cleaning help.
This kit contains the basics. There is the fluid, the plastic wand, and the lint-free cloth. It seems a bit complex the first time you do this cleaning, but the steps are simple once you go through it once:
- Prepare a clean, quiet, low-dust, low-airflow workspace where you won't be interrupted and can concentrate. Wash your hands thoroughly.
- Prepare a desktop workspace that is not cluttered and has a place for your camera and the cleaning supplies, including the sensor loupe (if you have it).
- Get your camera ready for sensor access (see steps above). Then put on the body cap over the sensor while you prepare the swab (steps below).
- For the first time, practice folding the Pec Pad cloth according to the directions. I would recommend just folding and refolding a cloth without worrying about actually using it the first time. Just practice until you can fold the cloth repeatedly without referring to the directions, then throw that practice cloth away.
- Start with a fresh Pec Pad and fold it by the instructions onto the plastic wand.
- Then open the body cap on the camera with the sensor ready for manual cleaning access.
- Put one or two drops on the cloth near the tip of the wand.
- Swab your sensor, according to directions, once on one side of the wand and once on the other.
- Resist the urge to re-use that cloth--take it off the wand and throw the cloth aside.
- Check your sensor with your loupe (if you have it) or using the f22 photo method to see if the cleaning was effective.
- If necessary, repeat a couple of times. Don't over-do it or get crazy and re-use a cloth or push too hard on the sensor. Each swab brings risks with it. Put the camera aside if you have tried it several times and still see a stubborn dust particle. I put the camera aside once with a dust particle still visible, but after using the camera for a few days, I examined the sensor again, and that particle was gone.
You'll need to get a supply of
Pec Pads, as you'll use those up
quite quickly.
You can also buy more Eclipse fluid
separately, but that seems to last a long time.
I also use these pads and fluid for cleaning camera filters and lenses.
Summary
Preparing these notes helped me understand the key ideas behind sensor cleaning:- The camera sensor attracts dust that can show up as blotches or spots on your photos.
- Due caution should be used in accessing or cleaning the sensor.
- The camera's automatic cleaning option is available.
- The camera's manual cleaning option allows you access to the sensor--but use a fresh battery.
- A sensor loupe can show the sensor closeup with special lighting to reveal dust.
- Blown air can clean the sensor.
- A special sensor brush can clean the sensor.
- A swab method of using drops of cleaning fluid on a dust-free cloth wrapped around a wand can clean the sensor.
Sources Consulted
- Canon EOS Rebel T1i: official reference site.