她真得很担心，因为拍出来的照片都多了一个黑点。。。
因为那天是星期日，她只能带着她的宝贝去Shalom找CK。
CK帮她“清理”了机里的灰尘，清洁了。
CK劝说要买“火箭”式的一种工具（Giotto Rocket Blower）。。。但到今天她还买。。。
看一有机会就要去买一些基本用具，偶尔要帮宝贝冲凉以下。。。
Clean Your Lens
There’s no way to avoid dust sticking to the front of your lens. You can prevent grime from
affixing itself directly to the front of your expensive lens by always keeping a filter such as a
Skylight filter attached. Many camera shops will suggest that you get a filter along with the
initial lens purchase, in fact. My opinion? I’d rather clean my lens occasionally than add an
inexpensive plate of glass to the front of my camera that will dilute the quality of my lens. But
your mileage may vary—if you prefer to use a filter to protect your lens, by all means do it. Even if you use a filter to protect your lens, you’ll still want to clean that occasionally.
So what do you need? Make sure your camera bag includes a blower, the kind you squeeze
with your hand to force air through a tube, not compressed air in a can. You should also have a
microfiber cloth and some lens cleaning fluid. My favorite blower is the awesome Giotto Rocket
Blower, which you can see in the following illustration:
Always start by blasting the dust off the lens with your blower. Harder-to-remove gunk, like
fingerprints, can be removed by wiping the lens in a circular motion with a microfiber cloth. If
necessary, add a couple of drops of the cleaning fluid to the cloth first.
caution:Never apply the fluid directly to the lens. Always put it on the cloth first.
Clean Your Sensor
Since dust can also find its way onto the sensor when you change lenses, let’s investigate how
to remove dust that builds up inside your D-SLR. Before we get too far, you should know that
cleaning the image sensor is a delicate operation. If you are not careful, you can damage the
sensor, which effectively ruins your expensive digital camera. If you don’t feel up to the task,
you can let your local camera shop do this for you. In reality, though, cleaning your sensor is not
difficult, it just sounds scary. Some prep work, the right tools, and common sense are all you need.
Detect Dust
Before you worry about the logistics of getting dust out of your camera, it’s helpful to know if
you really have a problem. Simply put, you know you have dust when you can see the same dark spots in a variety of your photos. You can scan your existing photos for telltale dust bunnies or
do it more methodically. Here’s how to do that.
~~Start by setting your camera to its lowest ISO, manual focus mode, and your lens’s smallest
aperture setting, such as f/22. Point it at a light-colored surface, such as a white wall or a large
white poster board and focus the camera. Since you’re shooting with a very small aperture, the
shutter speed might be several seconds. If it is, you might want to mount the camera on a tripod. Take a shot. Then reorient the camera. If you took your first picture in landscape mode, for
instance, take a second shot in portrait.
Now compare the photos, looking at them on your computer screen at 100 percent
magnification. Rotate the second picture so it is oriented the same as the first. If you see spots
in exactly the same place in both shots, congratulations, you’re the proud owner of dust on the
sensor. Check out two photos of my own camera’s sensor. Can you spot the dust
spots? I’ve circled them.
Tools of the Trade
To do the cleaning, you need to get some sensor cleaning gear from your local camera shop.
You’ll need a blower—again, the kind you squeeze with your hand, never a can of compressed
air. In addition, be sure the blower does not have any sort of brush or bristles on the end (you can use my recommended Rocket blower for this job too). You should also get specialized sensorcleaning swabs, which you’ll use to actually sweep the dust off your sensor. There are a number of popular brushes available, though I am fond of the Sensor Sweep II (www.copperhillimages .com). Another popular option is VisibleDust (www.visibledust.com). Delkin also sells the SensorScope (www.delkin.com), an all-in-one package that contains a bunch of sensor cleaning swabs, as well as a little vacuum and even an illuminated magnifying glass you can put on the camera’s lens mount to more easily see dirt on the sensor. You can see the sensor over the lens mount, ready to help you find dust.
Roll Up Your Sleeves…
Cleaning your sensor is an understandably scary proposition. If anything goes wrong, you can
end up damaging the most sensitive and expensive component of your camera, requiring a trip
to the equivalent of the camera emergency room: the manufacturer’s repair center. But as long as you’re diligent, careful, and use common sense, cleaning the sensor is little more than a routine maintenance operation.
Start by removing the lens and using the blower to blast any loose particles out of the mirror
chamber. Keep the camera pointed down so gravity will help get the dust out. Be sure that the
blower doesn’t come in direct contact with the mirror.
Next, get the mirror out of the way. You’ll need to refer to your camera’s user guide for
details on how to do this. Many Canon cameras, for example, have a sensor cleaning mode in the
menu, while some Nikon cameras have a mirror-up control that reveals the sensor, as you can
see in the following illustration. To be on the safe side, do this with your cameras connected to
AC power, because if your camera turns off because of a low battery, the mirror can snap back in place with no warning, trapping the brush in an ugly disaster.
Now you’ll want to use the blower to remove loose dirt, like you just did for the mirror. It’s
a good idea to do this while holding the camera upside down so gravity will help dust get blown
out of the camera, instead of just moving it around in the sensor chamber. Use the sensor swab
(with one or two drops of sensor cleaning fluid) to gently wipe away the more stubborn dirt
particles. Check the directions that came with the swab. You can see a typical sensor swab.
That’s all there is to it. Follow your camera manual’s instructions to disengage the mirror
lockup, and then take a couple of new test shots. Inspect them for signs of dust and, if necessary,
clean the sensor again. As long as you are careful about not leaving your sensor exposed to the
environment for long while you change lenses, you should only need to clean your sensor once
every six months or more.
TIP: Some Digital SLRs now come with a “self cleaning sensor.” These cameras vibrate the
sensor to shake dust loose. That’s a great feature, but it doesn’t completely eliminate the
need to clean the sensor by hand occasionally, since this automatic cleaning cycle only
shakes the dust around inside the chamber—and the electrostatic nature of the sensor
will eventually just attract the dust all over again.
Of course, there’s a relationship between aperture, shutter speed, and your film’s ISO rating as well. Look at Figure below. At any given film speed, you can take a picture with a specific aperture shutter combination. If you double the film speed without changing the lighting conditions, though, you have to adjust either the aperture or the shutter speed so that you still get a properly exposed picture.
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